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* [moderation/CI] Re: ext4: avoid infinite loops caused by data conflicts
@ 2026-03-01 14:55 syzbot ci
  2026-03-02 10:50 ` Pimyn Girgis
  2026-03-02 14:07 ` Aleksandr Nogikh
  0 siblings, 2 replies; 6+ messages in thread
From: syzbot ci @ 2026-03-01 14:55 UTC (permalink / raw)
  To: syzkaller-upstream-moderation; +Cc: syzbot

syzbot ci has tested the following series

[v1] ext4: avoid infinite loops caused by data conflicts
https://lore.kernel.org/all/tencent_4C5966F83C65375A97D236684A6C75237609@qq.com
* [PATCH] ext4: avoid infinite loops caused by data conflicts

and found the following issues:
* KASAN: slab-out-of-bounds Write in ext4_xattr_block_set
* KASAN: slab-use-after-free Read in do_exit
* KASAN: slab-use-after-free Write in ext4_xattr_block_set
* KASAN: use-after-free Write in ext4_xattr_block_set
* WARNING in ext4_xattr_block_set

Full report is available here:
https://ci.syzbot.org/series/175d31ab-3a77-4fe8-ba80-457d1e9b7ff0

***

KASAN: slab-out-of-bounds Write in ext4_xattr_block_set

tree:      torvalds
URL:       https://kernel.googlesource.com/pub/scm/linux/kernel/git/torvalds/linux
base:      eb71ab2bf72260054677e348498ba995a057c463
arch:      amd64
compiler:  Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8
config:    https://ci.syzbot.org/builds/fba2a0c2-e161-4ef9-a2c8-ddca4c80da09/config
C repro:   https://ci.syzbot.org/findings/7226f006-36f9-4dc2-8e42-67ddd1662a4a/c_repro
syz repro: https://ci.syzbot.org/findings/7226f006-36f9-4dc2-8e42-67ddd1662a4a/syz_repro

loop0: lost filesystem error report for type 5 error -117
EXT4-fs (loop0): mounted filesystem 00000000-0000-0000-0000-000000000000 r/w without journal. Quota mode: none.
==================================================================
BUG: KASAN: slab-out-of-bounds in ext4_xattr_block_set+0x247e/0x2b00 fs/ext4/xattr.c:2163
Write of size 1024 at addr ffff88810eafad08 by task syz.0.17/5950

CPU: 1 UID: 0 PID: 5950 Comm: syz.0.17 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:378 [inline]
 print_report+0xba/0x230 mm/kasan/report.c:482
 kasan_report+0x117/0x150 mm/kasan/report.c:595
 check_region_inline mm/kasan/generic.c:-1 [inline]
 kasan_check_range+0x264/0x2c0 mm/kasan/generic.c:200
 __asan_memcpy+0x40/0x70 mm/kasan/shadow.c:106
 ext4_xattr_block_set+0x247e/0x2b00 fs/ext4/xattr.c:2163
 ext4_xattr_move_to_block fs/ext4/xattr.c:2669 [inline]
 ext4_xattr_make_inode_space fs/ext4/xattr.c:2744 [inline]
 ext4_expand_extra_isize_ea+0x12e6/0x1eb0 fs/ext4/xattr.c:2832
 __ext4_expand_extra_isize+0x30d/0x400 fs/ext4/inode.c:6297
 ext4_try_to_expand_extra_isize fs/ext4/inode.c:6340 [inline]
 __ext4_mark_inode_dirty+0x45c/0x730 fs/ext4/inode.c:6418
 ext4_setattr+0x166e/0x1c60 fs/ext4/inode.c:5932
 notify_change+0xc1a/0xf40 fs/attr.c:556
 do_truncate+0x1c2/0x250 fs/open.c:68
 vfs_truncate+0x4b4/0x540 fs/open.c:118
 do_sys_truncate+0xf3/0x1c0 fs/open.c:142
 __do_sys_truncate fs/open.c:154 [inline]
 __se_sys_truncate fs/open.c:152 [inline]
 __x64_sys_truncate+0x5b/0x70 fs/open.c:152
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f608c79c799
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f608bdfe028 EFLAGS: 00000246 ORIG_RAX: 000000000000004c
RAX: ffffffffffffffda RBX: 00007f608ca15fa0 RCX: 00007f608c79c799
RDX: 0000000000000000 RSI: 0000000003000000 RDI: 0000200000000900
RBP: 00007f608c832bd9 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f608ca16038 R14: 00007f608ca15fa0 R15: 00007ffe3b059518
 </TASK>

The buggy address belongs to the physical page:
page: refcount:2 mapcount:0 mapping:ffff88810783d900 index:0x8 pfn:0x10eafa
memcg:ffff8881026b9b00
aops:def_blk_aops ino:700000 dentry name(?):""
flags: 0x17ff38000004a2c(referenced|uptodate|lru|workingset|owner_2|private|node=0|zone=2|lastcpupid=0x7ff)
raw: 017ff38000004a2c ffffea00044efa08 ffffea00043dc788 ffff88810783d900
raw: 0000000000000008 ffff8881bb9b4740 00000002ffffffff ffff8881026b9b00
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 0, migratetype Unmovable, gfp_mask 0x152c40(GFP_NOFS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_HARDWALL), pid 5814, tgid 5814 (udevd), ts 64590193146, free_ts 64427187441
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x231/0x280 mm/page_alloc.c:1889
 prep_new_page mm/page_alloc.c:1897 [inline]
 get_page_from_freelist+0x24dc/0x2580 mm/page_alloc.c:3962
 __alloc_frozen_pages_noprof+0x18d/0x380 mm/page_alloc.c:5250
 alloc_pages_mpol+0x232/0x4a0 mm/mempolicy.c:2484
 alloc_frozen_pages_noprof mm/mempolicy.c:2555 [inline]
 alloc_pages_noprof+0xa8/0x190 mm/mempolicy.c:2575
 folio_alloc_noprof+0x1e/0x30 mm/mempolicy.c:2585
 filemap_alloc_folio_noprof+0x111/0x470 mm/filemap.c:1013
 ractl_alloc_folio mm/readahead.c:189 [inline]
 page_cache_ra_unbounded+0x39b/0xa50 mm/readahead.c:277
 do_page_cache_ra mm/readahead.c:334 [inline]
 force_page_cache_ra+0x26e/0x2e0 mm/readahead.c:364
 filemap_get_pages+0x4c0/0x1f10 mm/filemap.c:2690
 filemap_read+0x447/0x1230 mm/filemap.c:2800
 blkdev_read_iter+0x30a/0x440 block/fops.c:855
 new_sync_read fs/read_write.c:493 [inline]
 vfs_read+0x582/0xa70 fs/read_write.c:574
 ksys_read+0x150/0x270 fs/read_write.c:717
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
page last free pid 12 tgid 12 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 __free_pages_prepare mm/page_alloc.c:1433 [inline]
 __free_frozen_pages+0xc2b/0xdb0 mm/page_alloc.c:2978
 vfree+0x25a/0x400 mm/vmalloc.c:3479
 __ebt_unregister_table+0x3d3/0x600 net/bridge/netfilter/ebtables.c:1174
 ops_exit_list net/core/net_namespace.c:199 [inline]
 ops_undo_list+0x49f/0x940 net/core/net_namespace.c:252
 cleanup_net+0x56b/0x800 net/core/net_namespace.c:704
 process_one_work kernel/workqueue.c:3275 [inline]
 process_scheduled_works+0xb02/0x1830 kernel/workqueue.c:3358
 worker_thread+0xa50/0xfc0 kernel/workqueue.c:3439
 kthread+0x388/0x470 kernel/kthread.c:467
 ret_from_fork+0x51e/0xb90 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

Memory state around the buggy address:
 ffff88810eafaf80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff88810eafb000: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff88810eafb080: 00 00 00 00 00 00 fc fc fc fc fc fc fc fc 00 00
                                     ^
 ffff88810eafb100: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff88810eafb180: 00 00 00 00 fc fc fc fc fc fc fc fc 00 00 00 00
==================================================================


***

KASAN: slab-use-after-free Read in do_exit

tree:      torvalds
URL:       https://kernel.googlesource.com/pub/scm/linux/kernel/git/torvalds/linux
base:      eb71ab2bf72260054677e348498ba995a057c463
arch:      amd64
compiler:  Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8
config:    https://ci.syzbot.org/builds/fba2a0c2-e161-4ef9-a2c8-ddca4c80da09/config
syz repro: https://ci.syzbot.org/findings/30fcf15f-7140-40ad-abff-af01ef67fdf0/syz_repro

==================================================================
BUG: KASAN: slab-use-after-free in stack_not_used kernel/exit.c:800 [inline]
BUG: KASAN: slab-use-after-free in check_stack_usage kernel/exit.c:849 [inline]
BUG: KASAN: slab-use-after-free in do_exit+0x1892/0x2320 kernel/exit.c:1006
Read of size 8 at addr ffffc900039c0748 by task kworker/R-ext4-/6060

CPU: 1 UID: 0 PID: 6060 Comm: kworker/R-ext4- Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:378 [inline]
 print_report+0xba/0x230 mm/kasan/report.c:482
 kasan_report+0x117/0x150 mm/kasan/report.c:595
 stack_not_used kernel/exit.c:800 [inline]
 check_stack_usage kernel/exit.c:849 [inline]
 do_exit+0x1892/0x2320 kernel/exit.c:1006
 kthread_exit+0x22b/0x280 kernel/kthread.c:336
 kthread+0x3a6/0x470 kernel/kthread.c:469
 ret_from_fork+0x51e/0xb90 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>

The buggy address belongs to stack of task kworker/R-ext4-/6060

The buggy address belongs to a 8-page vmalloc region starting at 0xffffc900039c0000 allocated at copy_process+0x508/0x3cf0 kernel/fork.c:2050
The buggy address belongs to the physical page:
page: refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x11ade0
flags: 0x17ff00000000000(node=0|zone=2|lastcpupid=0x7ff)
raw: 017ff00000000000 0000000000000000 dead000000000122 0000000000000000
raw: 0000000000000000 0000000000000000 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 0, migratetype Unmovable, gfp_mask 0x29c2(GFP_NOWAIT|__GFP_HIGHMEM|__GFP_IO|__GFP_FS|__GFP_ZERO), pid 2, tgid 2 (kthreadd), ts 65632032727, free_ts 57080349786
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x231/0x280 mm/page_alloc.c:1889
 prep_new_page mm/page_alloc.c:1897 [inline]
 get_page_from_freelist+0x24dc/0x2580 mm/page_alloc.c:3962
 __alloc_frozen_pages_noprof+0x18d/0x380 mm/page_alloc.c:5250
 alloc_pages_mpol+0x232/0x4a0 mm/mempolicy.c:2484
 alloc_frozen_pages_noprof mm/mempolicy.c:2555 [inline]
 alloc_pages_noprof+0xa8/0x190 mm/mempolicy.c:2575
 vm_area_alloc_pages mm/vmalloc.c:3662 [inline]
 __vmalloc_area_node mm/vmalloc.c:3876 [inline]
 __vmalloc_node_range_noprof+0x79b/0x1730 mm/vmalloc.c:4064
 __vmalloc_node_noprof+0xc2/0x100 mm/vmalloc.c:4124
 alloc_thread_stack_node kernel/fork.c:355 [inline]
 dup_task_struct+0x228/0x9a0 kernel/fork.c:924
 copy_process+0x508/0x3cf0 kernel/fork.c:2050
 kernel_clone+0x248/0x8e0 kernel/fork.c:2654
 kernel_thread+0x13f/0x1b0 kernel/fork.c:2715
 create_kthread kernel/kthread.c:490 [inline]
 kthreadd+0x4ec/0x6e0 kernel/kthread.c:848
 ret_from_fork+0x51e/0xb90 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
page last free pid 5859 tgid 5859 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 __free_pages_prepare mm/page_alloc.c:1433 [inline]
 __free_frozen_pages+0xc2b/0xdb0 mm/page_alloc.c:2978
 vfree+0x25a/0x400 mm/vmalloc.c:3479
 kcov_put kernel/kcov.c:442 [inline]
 kcov_close+0x28/0x50 kernel/kcov.c:543
 __fput+0x44f/0xa70 fs/file_table.c:469
 task_work_run+0x1d9/0x270 kernel/task_work.c:233
 exit_task_work include/linux/task_work.h:40 [inline]
 do_exit+0x69b/0x2320 kernel/exit.c:971
 do_group_exit+0x21b/0x2d0 kernel/exit.c:1112
 get_signal+0x1284/0x1330 kernel/signal.c:3034
 arch_do_signal_or_restart+0xbc/0x830 arch/x86/kernel/signal.c:337
 __exit_to_user_mode_loop kernel/entry/common.c:64 [inline]
 exit_to_user_mode_loop+0x86/0x480 kernel/entry/common.c:98
 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:226 [inline]
 syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:256 [inline]
 syscall_exit_to_user_mode include/linux/entry-common.h:325 [inline]
 do_syscall_64+0x32d/0xf80 arch/x86/entry/syscall_64.c:100
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Memory state around the buggy address:
 ffffc900039c0600: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffffc900039c0680: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffffc900039c0700: 00 00 00 00 00 00 00 00 00 fb 1d 00 01 00 00 00
                                              ^
 ffffc900039c0780: 00 00 00 00 00 00 00 00 00 00 00 00 00 02 00 00
 ffffc900039c0800: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
==================================================================


***

KASAN: slab-use-after-free Write in ext4_xattr_block_set

tree:      torvalds
URL:       https://kernel.googlesource.com/pub/scm/linux/kernel/git/torvalds/linux
base:      eb71ab2bf72260054677e348498ba995a057c463
arch:      amd64
compiler:  Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8
config:    https://ci.syzbot.org/builds/fba2a0c2-e161-4ef9-a2c8-ddca4c80da09/config
C repro:   https://ci.syzbot.org/findings/6fc160a0-280f-49cf-8793-84b846dbb3d4/c_repro
syz repro: https://ci.syzbot.org/findings/6fc160a0-280f-49cf-8793-84b846dbb3d4/syz_repro

EXT4-fs (loop0): 1 truncate cleaned up
EXT4-fs (loop0): mounted filesystem 00000000-0000-0000-0000-000000000000 r/w without journal. Quota mode: none.
==================================================================
BUG: KASAN: slab-use-after-free in ext4_xattr_block_set+0x247e/0x2b00 fs/ext4/xattr.c:2163
Write of size 1024 at addr ffff888166b09d08 by task syz.0.18/5961

CPU: 0 UID: 0 PID: 5961 Comm: syz.0.18 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:378 [inline]
 print_report+0xba/0x230 mm/kasan/report.c:482
 kasan_report+0x117/0x150 mm/kasan/report.c:595
 check_region_inline mm/kasan/generic.c:-1 [inline]
 kasan_check_range+0x264/0x2c0 mm/kasan/generic.c:200
 __asan_memcpy+0x40/0x70 mm/kasan/shadow.c:106
 ext4_xattr_block_set+0x247e/0x2b00 fs/ext4/xattr.c:2163
 ext4_xattr_move_to_block fs/ext4/xattr.c:2669 [inline]
 ext4_xattr_make_inode_space fs/ext4/xattr.c:2744 [inline]
 ext4_expand_extra_isize_ea+0x12e6/0x1eb0 fs/ext4/xattr.c:2832
 __ext4_expand_extra_isize+0x30d/0x400 fs/ext4/inode.c:6297
 ext4_try_to_expand_extra_isize fs/ext4/inode.c:6340 [inline]
 __ext4_mark_inode_dirty+0x45c/0x730 fs/ext4/inode.c:6418
 ext4_dirty_inode+0xd0/0x110 fs/ext4/inode.c:6450
 __mark_inode_dirty+0x3a4/0x1470 fs/fs-writeback.c:2609
 generic_update_time fs/inode.c:2198 [inline]
 touch_atime+0x576/0x6b0 fs/inode.c:2273
 file_accessed include/linux/fs.h:2263 [inline]
 filemap_read+0x1053/0x1230 mm/filemap.c:2872
 __kernel_read+0x504/0x9b0 fs/read_write.c:532
 integrity_kernel_read+0x89/0xd0 security/integrity/iint.c:28
 ima_calc_file_hash_tfm security/integrity/ima/ima_crypto.c:480 [inline]
 ima_calc_file_shash security/integrity/ima/ima_crypto.c:511 [inline]
 ima_calc_file_hash+0x12c3/0x17f0 security/integrity/ima/ima_crypto.c:568
 ima_collect_measurement+0x48b/0x930 security/integrity/ima/ima_api.c:295
 process_measurement+0x12cd/0x1c80 security/integrity/ima/ima_main.c:407
 ima_file_check+0xe1/0x130 security/integrity/ima/ima_main.c:667
 security_file_post_open+0xb3/0x260 security/security.c:2652
 do_open fs/namei.c:4673 [inline]
 path_openat+0x2e4d/0x3860 fs/namei.c:4830
 do_file_open+0x23e/0x4a0 fs/namei.c:4859
 do_sys_openat2+0x113/0x200 fs/open.c:1366
 do_sys_open fs/open.c:1372 [inline]
 __do_sys_openat fs/open.c:1388 [inline]
 __se_sys_openat fs/open.c:1383 [inline]
 __x64_sys_openat+0x138/0x170 fs/open.c:1383
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f0bb039c799
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f0baf9fe028 EFLAGS: 00000246 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 00007f0bb0615fa0 RCX: 00007f0bb039c799
RDX: 0000000000000042 RSI: 0000200000000040 RDI: ffffffffffffff9c
RBP: 00007f0bb0432bd9 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f0bb0616038 R14: 00007f0bb0615fa0 R15: 00007fff0f6badc8
 </TASK>

The buggy address belongs to the physical page:
page: refcount:2 mapcount:0 mapping:ffff88816785e480 index:0x8 pfn:0x166b09
memcg:ffff8881026d1b00
aops:def_blk_aops ino:700000 dentry name(?):""
flags: 0x57ff38000004a2c(referenced|uptodate|lru|workingset|owner_2|private|node=1|zone=2|lastcpupid=0x7ff)
raw: 057ff38000004a2c ffffea00069d7208 ffffea0005a8fac8 ffff88816785e480
raw: 0000000000000008 ffff888119801740 00000002ffffffff ffff8881026d1b00
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 0, migratetype Unmovable, gfp_mask 0x152c40(GFP_NOFS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_HARDWALL), pid 5814, tgid 5814 (udevd), ts 66017733899, free_ts 66011346759
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x231/0x280 mm/page_alloc.c:1889
 prep_new_page mm/page_alloc.c:1897 [inline]
 get_page_from_freelist+0x24dc/0x2580 mm/page_alloc.c:3962
 __alloc_frozen_pages_noprof+0x18d/0x380 mm/page_alloc.c:5250
 alloc_pages_mpol+0x232/0x4a0 mm/mempolicy.c:2484
 alloc_frozen_pages_noprof mm/mempolicy.c:2555 [inline]
 alloc_pages_noprof+0xa8/0x190 mm/mempolicy.c:2575
 folio_alloc_noprof+0x1e/0x30 mm/mempolicy.c:2585
 filemap_alloc_folio_noprof+0x111/0x470 mm/filemap.c:1013
 ractl_alloc_folio mm/readahead.c:189 [inline]
 page_cache_ra_unbounded+0x39b/0xa50 mm/readahead.c:277
 do_page_cache_ra mm/readahead.c:334 [inline]
 force_page_cache_ra+0x26e/0x2e0 mm/readahead.c:364
 filemap_get_pages+0x4c0/0x1f10 mm/filemap.c:2690
 filemap_read+0x447/0x1230 mm/filemap.c:2800
 blkdev_read_iter+0x30a/0x440 block/fops.c:855
 new_sync_read fs/read_write.c:493 [inline]
 vfs_read+0x582/0xa70 fs/read_write.c:574
 ksys_read+0x150/0x270 fs/read_write.c:717
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
page last free pid 5814 tgid 5814 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 __free_pages_prepare mm/page_alloc.c:1433 [inline]
 free_unref_folios+0xed5/0x16d0 mm/page_alloc.c:3040
 folios_put_refs+0x789/0x8d0 mm/swap.c:1002
 folios_put include/linux/mm.h:1876 [inline]
 folio_batch_move_lru+0x39d/0x430 mm/swap.c:179
 lru_add_drain_cpu+0xb8/0x7b0 mm/swap.c:648
 lru_add_drain+0x121/0x3e0 mm/swap.c:737
 __folio_batch_release+0x48/0x90 mm/swap.c:1059
 folio_batch_release include/linux/pagevec.h:101 [inline]
 shmem_undo_range+0x52c/0x1660 mm/shmem.c:1149
 shmem_truncate_range mm/shmem.c:1277 [inline]
 shmem_evict_inode+0x240/0x9e0 mm/shmem.c:1407
 evict+0x61e/0xb10 fs/inode.c:846
 __dentry_kill+0x1a2/0x5e0 fs/dcache.c:670
 finish_dput+0xc9/0x480 fs/dcache.c:879
 end_renaming fs/namei.c:4096 [inline]
 filename_renameat2+0x61e/0x9c0 fs/namei.c:6146
 __do_sys_rename fs/namei.c:6188 [inline]
 __se_sys_rename+0x55/0x2c0 fs/namei.c:6184
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Memory state around the buggy address:
 ffff888166b09f00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff888166b09f80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff888166b0a000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                   ^
 ffff888166b0a080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888166b0a100: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
==================================================================


***

KASAN: use-after-free Write in ext4_xattr_block_set

tree:      torvalds
URL:       https://kernel.googlesource.com/pub/scm/linux/kernel/git/torvalds/linux
base:      eb71ab2bf72260054677e348498ba995a057c463
arch:      amd64
compiler:  Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8
config:    https://ci.syzbot.org/builds/fba2a0c2-e161-4ef9-a2c8-ddca4c80da09/config
C repro:   https://ci.syzbot.org/findings/64472648-05ba-4d64-b168-bb54f3f15702/c_repro
syz repro: https://ci.syzbot.org/findings/64472648-05ba-4d64-b168-bb54f3f15702/syz_repro

fscrypt: AES-256-CBC-CTS using implementation "cts(cbc(ecb(aes-lib)))"
fscrypt: AES-256-XTS using implementation "xts(ecb(aes-lib))"
==================================================================
BUG: KASAN: use-after-free in ext4_xattr_block_set+0x247e/0x2b00 fs/ext4/xattr.c:2163
Write of size 4096 at addr ffff8881ba262108 by task syz.0.17/5950

CPU: 1 UID: 0 PID: 5950 Comm: syz.0.17 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:378 [inline]
 print_report+0xba/0x230 mm/kasan/report.c:482
 kasan_report+0x117/0x150 mm/kasan/report.c:595
 check_region_inline mm/kasan/generic.c:-1 [inline]
 kasan_check_range+0x264/0x2c0 mm/kasan/generic.c:200
 __asan_memcpy+0x40/0x70 mm/kasan/shadow.c:106
 ext4_xattr_block_set+0x247e/0x2b00 fs/ext4/xattr.c:2163
 ext4_xattr_set_handle+0xe37/0x14d0 fs/ext4/xattr.c:2457
 ext4_xattr_set+0x255/0x340 fs/ext4/xattr.c:2559
 __vfs_setxattr+0x43c/0x480 fs/xattr.c:200
 __vfs_setxattr_noperm+0x12d/0x660 fs/xattr.c:234
 vfs_setxattr+0x163/0x360 fs/xattr.c:321
 ovl_do_setxattr fs/overlayfs/overlayfs.h:317 [inline]
 ovl_setxattr fs/overlayfs/overlayfs.h:329 [inline]
 ovl_verify_set_fh+0x136/0x200 fs/overlayfs/namei.c:556
 ovl_verify_origin_xattr+0x98/0x180 fs/overlayfs/namei.c:584
 ovl_verify_upper fs/overlayfs/overlayfs.h:757 [inline]
 ovl_get_indexdir+0x4aa/0x600 fs/overlayfs/super.c:898
 ovl_fill_super_creds fs/overlayfs/super.c:1478 [inline]
 ovl_fill_super+0x37f3/0x5e00 fs/overlayfs/super.c:1564
 vfs_get_super fs/super.c:1327 [inline]
 get_tree_nodev+0xbb/0x150 fs/super.c:1346
 vfs_get_tree+0x92/0x2a0 fs/super.c:1754
 fc_mount fs/namespace.c:1193 [inline]
 do_new_mount_fc fs/namespace.c:3763 [inline]
 do_new_mount+0x341/0xd30 fs/namespace.c:3839
 do_mount fs/namespace.c:4172 [inline]
 __do_sys_mount fs/namespace.c:4361 [inline]
 __se_sys_mount+0x31d/0x420 fs/namespace.c:4338
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7ffbced9c799
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffd4392dda8 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007ffbcf015fa0 RCX: 00007ffbced9c799
RDX: 0000200000000140 RSI: 0000200000000100 RDI: 0000000000000000
RBP: 00007ffbcee32bd9 R08: 0000200000000180 R09: 0000000000000000
R10: 0000000000000008 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ffbcf015fac R14: 00007ffbcf015fa0 R15: 00007ffbcf015fa0
 </TASK>

The buggy address belongs to the physical page:
page: refcount:3 mapcount:0 mapping:ffff888107834200 index:0xe0 pfn:0x1ba262
memcg:ffff88816c071b00
aops:def_blk_aops ino:700000 dentry name(?):""
flags: 0x57ff08000004004(referenced|private|node=1|zone=2|lastcpupid=0x7ff)
raw: 057ff08000004004 0000000000000000 dead000000000122 ffff888107834200
raw: 00000000000000e0 ffff8881bc57f658 00000003ffffffff ffff88816c071b00
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 0, migratetype Movable, gfp_mask 0x148c48(GFP_NOFS|__GFP_MOVABLE|__GFP_NOFAIL|__GFP_COMP|__GFP_HARDWALL), pid 5950, tgid 5950 (syz.0.17), ts 65596023731, free_ts 65574666721
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x231/0x280 mm/page_alloc.c:1889
 prep_new_page mm/page_alloc.c:1897 [inline]
 get_page_from_freelist+0x24dc/0x2580 mm/page_alloc.c:3962
 __alloc_frozen_pages_noprof+0x18d/0x380 mm/page_alloc.c:5250
 alloc_pages_mpol+0x232/0x4a0 mm/mempolicy.c:2484
 alloc_frozen_pages_noprof mm/mempolicy.c:2555 [inline]
 alloc_pages_noprof+0xa8/0x190 mm/mempolicy.c:2575
 folio_alloc_noprof+0x1e/0x30 mm/mempolicy.c:2585
 filemap_alloc_folio_noprof+0x111/0x470 mm/filemap.c:1013
 __filemap_get_folio_mpol+0x3fc/0xb00 mm/filemap.c:2006
 __filemap_get_folio include/linux/pagemap.h:774 [inline]
 grow_dev_folio fs/buffer.c:1047 [inline]
 grow_buffers fs/buffer.c:1113 [inline]
 __getblk_slow fs/buffer.c:1131 [inline]
 bdev_getblk+0x1f6/0x6e0 fs/buffer.c:1458
 __getblk include/linux/buffer_head.h:380 [inline]
 sb_getblk include/linux/buffer_head.h:386 [inline]
 ext4_xattr_block_set+0x1d9c/0x2b00 fs/ext4/xattr.c:2131
 ext4_xattr_set_handle+0xe37/0x14d0 fs/ext4/xattr.c:2457
 ext4_xattr_set+0x255/0x340 fs/ext4/xattr.c:2559
 __vfs_setxattr+0x43c/0x480 fs/xattr.c:200
 __vfs_setxattr_noperm+0x12d/0x660 fs/xattr.c:234
 vfs_setxattr+0x163/0x360 fs/xattr.c:321
 ovl_do_setxattr fs/overlayfs/overlayfs.h:317 [inline]
 ovl_setxattr fs/overlayfs/overlayfs.h:329 [inline]
 ovl_verify_set_fh+0x136/0x200 fs/overlayfs/namei.c:556
page last free pid 5959 tgid 5959 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 __free_pages_prepare mm/page_alloc.c:1433 [inline]
 free_unref_folios+0xed5/0x16d0 mm/page_alloc.c:3040
 folios_put_refs+0x789/0x8d0 mm/swap.c:1002
 free_pages_and_swap_cache+0x537/0x5b0 mm/swap_state.c:426
 __tlb_batch_free_encoded_pages mm/mmu_gather.c:138 [inline]
 tlb_batch_pages_flush mm/mmu_gather.c:151 [inline]
 tlb_flush_mmu_free mm/mmu_gather.c:398 [inline]
 tlb_flush_mmu+0x6d3/0xa30 mm/mmu_gather.c:405
 tlb_finish_mmu+0xf9/0x230 mm/mmu_gather.c:530
 exit_mmap+0x498/0xa10 mm/mmap.c:1315
 __mmput+0x118/0x430 kernel/fork.c:1174
 exit_mm+0x168/0x220 kernel/exit.c:581
 do_exit+0x62e/0x2320 kernel/exit.c:959
 do_group_exit+0x21b/0x2d0 kernel/exit.c:1112
 __do_sys_exit_group kernel/exit.c:1123 [inline]
 __se_sys_exit_group kernel/exit.c:1121 [inline]
 __x64_sys_exit_group+0x3f/0x40 kernel/exit.c:1121
 x64_sys_call+0x221a/0x2240 arch/x86/include/generated/asm/syscalls_64.h:232
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Memory state around the buggy address:
 ffff8881ba262f00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff8881ba262f80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff8881ba263000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                   ^
 ffff8881ba263080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff8881ba263100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
==================================================================


***

WARNING in ext4_xattr_block_set

tree:      torvalds
URL:       https://kernel.googlesource.com/pub/scm/linux/kernel/git/torvalds/linux
base:      eb71ab2bf72260054677e348498ba995a057c463
arch:      amd64
compiler:  Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8
config:    https://ci.syzbot.org/builds/fba2a0c2-e161-4ef9-a2c8-ddca4c80da09/config
C repro:   https://ci.syzbot.org/findings/842bc2c4-3a27-4dcd-9ff1-64e538e1ea22/c_repro
syz repro: https://ci.syzbot.org/findings/842bc2c4-3a27-4dcd-9ff1-64e538e1ea22/syz_repro

EXT4-fs: Warning: mounting with data=journal disables delayed allocation, dioread_nolock, O_DIRECT and fast_commit support!
EXT4-fs (loop0): encrypted files will use data=ordered instead of data journaling mode
------------[ cut here ]------------
!PageLargeKmalloc(page)
WARNING: mm/slub.c:6371 at free_large_kmalloc+0xa3/0x140 mm/slub.c:6371, CPU#0: syz.0.17/5958
Modules linked in:
CPU: 0 UID: 0 PID: 5958 Comm: syz.0.17 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
RIP: 0010:free_large_kmalloc+0xa3/0x140 mm/slub.c:6371
Code: f8 ff 74 17 25 00 00 00 ff 3d 00 00 00 f8 0f 85 a0 00 00 00 c7 43 30 ff ff ff ff 48 89 df 89 ee 5b 41 5e 5d e9 ee c7 fc ff 90 <0f> 0b 90 48 89 df 48 c7 c6 fb d9 f0 8d 5b 41 5e 5d e9 97 f2 03 ff
RSP: 0018:ffffc90005dff0e0 EFLAGS: 00010206
RAX: 00000000ff000000 RBX: ffffea000599df00 RCX: ffff888173089d01
RDX: 0000000000000000 RSI: ffff88816677c508 RDI: ffffea000599df00
RBP: 0000000000000000 R08: ffff888108c77063 R09: 1ffff1102118ee0c
R10: dffffc0000000000 R11: ffffed102118ee0d R12: 0000000000000000
R13: dffffc0000000000 R14: ffff88816677c508 R15: 0000000000000000
FS:  0000555583178500(0000) GS:ffff88818de63000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007ffe5501a000 CR3: 000000017552a000 CR4: 00000000000006f0
Call Trace:
 <TASK>
 ext4_xattr_block_set+0x2102/0x2b00 fs/ext4/xattr.c:2210
 ext4_xattr_move_to_block fs/ext4/xattr.c:2669 [inline]
 ext4_xattr_make_inode_space fs/ext4/xattr.c:2744 [inline]
 ext4_expand_extra_isize_ea+0x12e6/0x1eb0 fs/ext4/xattr.c:2832
 __ext4_expand_extra_isize+0x30d/0x400 fs/ext4/inode.c:6297
 ext4_try_to_expand_extra_isize fs/ext4/inode.c:6340 [inline]
 __ext4_mark_inode_dirty+0x45c/0x730 fs/ext4/inode.c:6418
 ext4_inline_data_truncate+0x76b/0xb40 fs/ext4/inline.c:1940
 ext4_truncate+0x3b5/0x13b0 fs/ext4/inode.c:4518
 ext4_process_orphan+0x1cb/0x300 fs/ext4/orphan.c:337
 ext4_orphan_cleanup+0xc38/0x1470 fs/ext4/orphan.c:472
 __ext4_fill_super fs/ext4/super.c:5668 [inline]
 ext4_fill_super+0x59ff/0x6320 fs/ext4/super.c:5791
 get_tree_bdev_flags+0x431/0x4f0 fs/super.c:1694
 vfs_get_tree+0x92/0x2a0 fs/super.c:1754
 fc_mount fs/namespace.c:1193 [inline]
 do_new_mount_fc fs/namespace.c:3763 [inline]
 do_new_mount+0x341/0xd30 fs/namespace.c:3839
 do_mount fs/namespace.c:4172 [inline]
 __do_sys_mount fs/namespace.c:4361 [inline]
 __se_sys_mount+0x31d/0x420 fs/namespace.c:4338
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f59e879da0a
Code: 48 c7 c2 e8 ff ff ff f7 d8 64 89 02 b8 ff ff ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 49 89 ca b8 a5 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffe550193e8 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007ffe55019470 RCX: 00007f59e879da0a
RDX: 0000200000000040 RSI: 00002000000001c0 RDI: 00007ffe55019430
RBP: 0000200000000040 R08: 00007ffe55019470 R09: 0000000000000404
R10: 0000000000000404 R11: 0000000000000246 R12: 00002000000001c0
R13: 00007ffe55019430 R14: 0000000000000442 R15: 0000200000000300
 </TASK>


***

If these findings have caused you to resend the series or submit a
separate fix, please add the following tag to your commit message:
  Tested-by: syzbot@syzkaller.appspotmail.com

---
This report is generated by a bot. It may contain errors.
syzbot ci engineers can be reached at syzkaller@googlegroups.com.

The email will later be sent to:
[brauner@kernel.org eadavis@qq.com jack@suse.cz linux-ext4@vger.kernel.org linux-fsdevel@vger.kernel.org linux-kernel@vger.kernel.org syzbot@syzkaller.appspotmail.com syzkaller-bugs@googlegroups.com viro@zeniv.linux.org.uk]

If the report looks fine to you, reply with:
#syz upstream

If the report is a false positive, reply with
#syz invalid


^ permalink raw reply	[flat|nested] 6+ messages in thread
* [moderation/CI] Re: ext4: avoid infinite loops caused by data conflicts
@ 2026-03-02 19:01 syzbot ci
  2026-03-03  7:46 ` Pimyn Girgis
  0 siblings, 1 reply; 6+ messages in thread
From: syzbot ci @ 2026-03-02 19:01 UTC (permalink / raw)
  To: syzkaller-upstream-moderation; +Cc: syzbot

syzbot ci has tested the following series

[v2] ext4: avoid infinite loops caused by data conflicts
https://lore.kernel.org/all/tencent_13E236704A527419766767443D6736EE9609@qq.com
* [PATCH v2] ext4: avoid infinite loops caused by data conflicts

and found the following issues:
* KASAN: slab-out-of-bounds Read in ext4_xattr_block_csum_set
* KASAN: slab-use-after-free Read in ext4_xattr_block_csum_set
* KASAN: slab-use-after-free Read in ext4_xattr_set_entry
* KASAN: use-after-free Read in ext4_xattr_block_csum_set
* KASAN: use-after-free Read in ext4_xattr_set_entry

Full report is available here:
https://ci.syzbot.org/series/ccbb03e4-9312-48f0-808d-923f86d83f2f

***

KASAN: slab-out-of-bounds Read in ext4_xattr_block_csum_set

tree:      torvalds
URL:       https://kernel.googlesource.com/pub/scm/linux/kernel/git/torvalds/linux
base:      11439c4635edd669ae435eec308f4ab8a0804808
arch:      amd64
compiler:  Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8
config:    https://ci.syzbot.org/builds/330c6289-adc9-452b-b12f-000d32045593/config
syz repro: https://ci.syzbot.org/findings/ddaf8105-c8d7-4a57-87ef-ee750875c5c7/syz_repro

fscrypt: AES-256-CBC-CTS using implementation "cts(cbc(ecb(aes-lib)))"
==================================================================
BUG: KASAN: slab-out-of-bounds in crc32c_base lib/crc/crc32-main.c:54 [inline]
BUG: KASAN: slab-out-of-bounds in crc32c_arch lib/crc/x86/crc32.h:44 [inline]
BUG: KASAN: slab-out-of-bounds in crc32c+0x3cc/0x470 lib/crc/crc32-main.c:86
Read of size 1 at addr ffff88816a0ea0b0 by task syz.0.17/6006

CPU: 1 UID: 0 PID: 6006 Comm: syz.0.17 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:378 [inline]
 print_report+0xba/0x230 mm/kasan/report.c:482
 kasan_report+0x117/0x150 mm/kasan/report.c:595
 crc32c_base lib/crc/crc32-main.c:54 [inline]
 crc32c_arch lib/crc/x86/crc32.h:44 [inline]
 crc32c+0x3cc/0x470 lib/crc/crc32-main.c:86
 ext4_chksum fs/ext4/ext4.h:2553 [inline]
 ext4_xattr_block_csum fs/ext4/xattr.c:147 [inline]
 ext4_xattr_block_csum_set+0x241/0x330 fs/ext4/xattr.c:172
 ext4_xattr_block_set+0x2494/0x2b00 fs/ext4/xattr.c:2165
 ext4_xattr_set_handle+0xe37/0x14d0 fs/ext4/xattr.c:2458
 ext4_set_context+0x233/0x560 fs/ext4/crypto.c:166
 fscrypt_set_context+0x397/0x460 fs/crypto/policy.c:791
 __ext4_new_inode+0x3158/0x3d20 fs/ext4/ialloc.c:1314
 ext4_mkdir+0x3da/0xbf0 fs/ext4/namei.c:3005
 vfs_mkdir+0x413/0x630 fs/namei.c:5233
 filename_mkdirat+0x285/0x510 fs/namei.c:5266
 __do_sys_mkdirat fs/namei.c:5287 [inline]
 __se_sys_mkdirat+0x35/0x150 fs/namei.c:5284
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fb60ad9c799
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fb60bd17028 EFLAGS: 00000246 ORIG_RAX: 0000000000000102
RAX: ffffffffffffffda RBX: 00007fb60b015fa0 RCX: 00007fb60ad9c799
RDX: 00000000000001c0 RSI: 0000200000000180 RDI: ffffffffffffff9c
RBP: 00007fb60ae32bd9 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fb60b016038 R14: 00007fb60b015fa0 R15: 00007fff4bbf7228
 </TASK>

Allocated by task 1:
 kasan_save_stack mm/kasan/common.c:57 [inline]
 kasan_save_track+0x3e/0x80 mm/kasan/common.c:78
 unpoison_slab_object mm/kasan/common.c:340 [inline]
 __kasan_slab_alloc+0x6c/0x80 mm/kasan/common.c:366
 kasan_slab_alloc include/linux/kasan.h:253 [inline]
 slab_post_alloc_hook mm/slub.c:4515 [inline]
 slab_alloc_node mm/slub.c:4844 [inline]
 kmem_cache_alloc_noprof+0x2bc/0x650 mm/slub.c:4851
 __kernfs_new_node+0xe9/0x8e0 fs/kernfs/dir.c:637
 kernfs_new_node+0x102/0x210 fs/kernfs/dir.c:718
 __kernfs_create_file+0x4b/0x2e0 fs/kernfs/file.c:1057
 sysfs_add_file_mode_ns+0x238/0x300 fs/sysfs/file.c:313
 create_files fs/sysfs/group.c:82 [inline]
 internal_create_group+0x673/0x1180 fs/sysfs/group.c:189
 internal_create_groups fs/sysfs/group.c:229 [inline]
 sysfs_create_groups+0x59/0x120 fs/sysfs/group.c:255
 device_add_groups drivers/base/core.c:2836 [inline]
 device_add_attrs+0xdd/0x5b0 drivers/base/core.c:2900
 device_add+0x496/0xb70 drivers/base/core.c:3643
 __video_register_device+0x3e40/0x4d20 drivers/media/v4l2-core/v4l2-dev.c:1076
 video_register_device include/media/v4l2-dev.h:390 [inline]
 vivid_create_devnodes+0xc5e/0x2bf0 drivers/media/test-drivers/vivid/vivid-core.c:1471
 vivid_create_instance drivers/media/test-drivers/vivid/vivid-core.c:2042 [inline]
 vivid_probe+0x510d/0x72b0 drivers/media/test-drivers/vivid/vivid-core.c:2095
 platform_probe+0xf9/0x190 drivers/base/platform.c:1446
 call_driver_probe drivers/base/dd.c:-1 [inline]
 really_probe+0x267/0xaf0 drivers/base/dd.c:661
 __driver_probe_device+0x18c/0x320 drivers/base/dd.c:803
 driver_probe_device+0x4f/0x240 drivers/base/dd.c:833
 __driver_attach+0x3e7/0x710 drivers/base/dd.c:1227
 bus_for_each_dev+0x23b/0x2c0 drivers/base/bus.c:383
 bus_add_driver+0x345/0x670 drivers/base/bus.c:715
 driver_register+0x23a/0x320 drivers/base/driver.c:249
 vivid_init+0x561/0x5f0 drivers/media/test-drivers/vivid/vivid-core.c:2294
 do_one_initcall+0x250/0x8d0 init/main.c:1382
 do_initcall_level+0x104/0x190 init/main.c:1444
 do_initcalls+0x59/0xa0 init/main.c:1460
 kernel_init_freeable+0x2a6/0x3e0 init/main.c:1692
 kernel_init+0x1d/0x1d0 init/main.c:1582
 ret_from_fork+0x51e/0xb90 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

The buggy address belongs to the object at ffff88816a0ea000
 which belongs to the cache kernfs_node_cache of size 176
The buggy address is located 0 bytes to the right of
 allocated 176-byte region [ffff88816a0ea000, ffff88816a0ea0b0)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x16a0ea
flags: 0x57ff00000000000(node=1|zone=2|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 057ff00000000000 ffff8881012d3dc0 dead000000000122 0000000000000000
raw: 0000000000000000 0000000800110011 00000000f5000000 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 0, migratetype Unmovable, gfp_mask 0xd2cc0(GFP_KERNEL|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 1, tgid 1 (swapper/0), ts 19200276917, free_ts 4632825873
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x231/0x280 mm/page_alloc.c:1889
 prep_new_page mm/page_alloc.c:1897 [inline]
 get_page_from_freelist+0x24dc/0x2580 mm/page_alloc.c:3962
 __alloc_frozen_pages_noprof+0x18d/0x380 mm/page_alloc.c:5250
 alloc_slab_page mm/slub.c:3269 [inline]
 allocate_slab+0x77/0x660 mm/slub.c:3458
 new_slab mm/slub.c:3516 [inline]
 refill_objects+0x331/0x3c0 mm/slub.c:7153
 refill_sheaf mm/slub.c:2818 [inline]
 __pcs_replace_empty_main+0x2b9/0x620 mm/slub.c:4592
 alloc_from_pcs mm/slub.c:4695 [inline]
 slab_alloc_node mm/slub.c:4829 [inline]
 kmem_cache_alloc_noprof+0x37d/0x650 mm/slub.c:4851
 __kernfs_new_node+0xe9/0x8e0 fs/kernfs/dir.c:637
 kernfs_new_node+0x102/0x210 fs/kernfs/dir.c:718
 kernfs_create_link+0xa7/0x200 fs/kernfs/symlink.c:39
 sysfs_do_create_link_sd+0x83/0x110 fs/sysfs/symlink.c:44
 device_create_sys_dev_entry+0x122/0x190 drivers/base/core.c:3515
 device_add+0x733/0xb70 drivers/base/core.c:3659
 cdev_device_add+0x1d6/0x390 fs/char_dev.c:553
 media_devnode_register+0x287/0x420 drivers/media/mc/mc-devnode.c:247
 __media_device_register+0x15c/0x3c0 drivers/media/mc/mc-device.c:753
page last free pid 10 tgid 10 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 __free_pages_prepare mm/page_alloc.c:1433 [inline]
 __free_frozen_pages+0xc2b/0xdb0 mm/page_alloc.c:2978
 vfree+0x25a/0x400 mm/vmalloc.c:3479
 delayed_vfree_work+0x55/0x80 mm/vmalloc.c:3398
 process_one_work kernel/workqueue.c:3275 [inline]
 process_scheduled_works+0xb02/0x1830 kernel/workqueue.c:3358
 worker_thread+0xa50/0xfc0 kernel/workqueue.c:3439
 kthread+0x388/0x470 kernel/kthread.c:467
 ret_from_fork+0x51e/0xb90 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

Memory state around the buggy address:
 ffff88816a0e9f80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff88816a0ea000: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff88816a0ea080: 00 00 00 00 00 00 fc fc fc fc fc fc fc fc 00 00
                                     ^
 ffff88816a0ea100: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff88816a0ea180: 00 00 00 00 fc fc fc fc fc fc fc fc 00 00 00 00
==================================================================


***

KASAN: slab-use-after-free Read in ext4_xattr_block_csum_set

tree:      torvalds
URL:       https://kernel.googlesource.com/pub/scm/linux/kernel/git/torvalds/linux
base:      11439c4635edd669ae435eec308f4ab8a0804808
arch:      amd64
compiler:  Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8
config:    https://ci.syzbot.org/builds/330c6289-adc9-452b-b12f-000d32045593/config
C repro:   https://ci.syzbot.org/findings/bee8f041-a020-4e43-a068-e014486583d9/c_repro
syz repro: https://ci.syzbot.org/findings/bee8f041-a020-4e43-a068-e014486583d9/syz_repro

ext4 filesystem being mounted at /0/file0 supports timestamps until 2038-01-19 (0x7fffffff)
fscrypt: AES-256-CBC-CTS using implementation "cts(cbc(ecb(aes-lib)))"
==================================================================
BUG: KASAN: slab-use-after-free in crc32c_base lib/crc/crc32-main.c:54 [inline]
BUG: KASAN: slab-use-after-free in crc32c_arch lib/crc/x86/crc32.h:44 [inline]
BUG: KASAN: slab-use-after-free in crc32c+0x3cc/0x470 lib/crc/crc32-main.c:86
Read of size 1 at addr ffff88816c2f9000 by task syz.0.17/5966

CPU: 0 UID: 0 PID: 5966 Comm: syz.0.17 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:378 [inline]
 print_report+0xba/0x230 mm/kasan/report.c:482
 kasan_report+0x117/0x150 mm/kasan/report.c:595
 crc32c_base lib/crc/crc32-main.c:54 [inline]
 crc32c_arch lib/crc/x86/crc32.h:44 [inline]
 crc32c+0x3cc/0x470 lib/crc/crc32-main.c:86
 ext4_chksum fs/ext4/ext4.h:2553 [inline]
 ext4_xattr_block_csum fs/ext4/xattr.c:147 [inline]
 ext4_xattr_block_csum_set+0x241/0x330 fs/ext4/xattr.c:172
 ext4_xattr_block_set+0x2494/0x2b00 fs/ext4/xattr.c:2165
 ext4_xattr_set_handle+0xe37/0x14d0 fs/ext4/xattr.c:2458
 ext4_set_context+0x233/0x560 fs/ext4/crypto.c:166
 fscrypt_set_context+0x397/0x460 fs/crypto/policy.c:791
 __ext4_new_inode+0x3158/0x3d20 fs/ext4/ialloc.c:1314
 ext4_mkdir+0x3da/0xbf0 fs/ext4/namei.c:3005
 vfs_mkdir+0x413/0x630 fs/namei.c:5233
 filename_mkdirat+0x285/0x510 fs/namei.c:5266
 __do_sys_mkdir fs/namei.c:5293 [inline]
 __se_sys_mkdir+0x34/0x150 fs/namei.c:5290
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fb91ff9c799
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffe3b8b33f8 EFLAGS: 00000246 ORIG_RAX: 0000000000000053
RAX: ffffffffffffffda RBX: 00007fb920215fa0 RCX: 00007fb91ff9c799
RDX: 0000000000000000 RSI: 0000000000000142 RDI: 0000200000000300
RBP: 00007fb920032bd9 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fb920215fac R14: 00007fb920215fa0 R15: 00007fb920215fa0
 </TASK>

Allocated by task 5807:
 kasan_save_stack mm/kasan/common.c:57 [inline]
 kasan_save_track+0x3e/0x80 mm/kasan/common.c:78
 poison_kmalloc_redzone mm/kasan/common.c:398 [inline]
 __kasan_kmalloc+0x93/0xb0 mm/kasan/common.c:415
 kasan_kmalloc include/linux/kasan.h:263 [inline]
 __kmalloc_cache_noprof+0x31c/0x660 mm/slub.c:5358
 kmalloc_noprof include/linux/slab.h:950 [inline]
 slab_free_hook mm/slub.c:2644 [inline]
 slab_free mm/slub.c:6143 [inline]
 kmem_cache_free+0x15b/0x630 mm/slub.c:6273
 anon_vma_free mm/rmap.c:137 [inline]
 __put_anon_vma+0x12b/0x2d0 mm/rmap.c:2889
 put_anon_vma mm/internal.h:215 [inline]
 unlink_anon_vmas+0x58b/0x730 mm/rmap.c:529
 free_pgtables+0x663/0xb70 mm/memory.c:414
 exit_mmap+0x490/0xa10 mm/mmap.c:1314
 __mmput+0x118/0x430 kernel/fork.c:1174
 exec_mmap+0x3b4/0x440 fs/exec.c:893
 begin_new_exec+0x134a/0x24a0 fs/exec.c:1148
 load_elf_binary+0xa47/0x2980 fs/binfmt_elf.c:1011
 search_binary_handler fs/exec.c:1664 [inline]
 exec_binprm fs/exec.c:1696 [inline]
 bprm_execve+0x93d/0x1460 fs/exec.c:1748
 do_execveat_common+0x50d/0x690 fs/exec.c:1846
 __do_sys_execve fs/exec.c:1930 [inline]
 __se_sys_execve fs/exec.c:1924 [inline]
 __x64_sys_execve+0x97/0xc0 fs/exec.c:1924
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Freed by task 5807:
 kasan_save_stack mm/kasan/common.c:57 [inline]
 kasan_save_track+0x3e/0x80 mm/kasan/common.c:78
 kasan_save_free_info+0x46/0x50 mm/kasan/generic.c:584
 poison_slab_object mm/kasan/common.c:253 [inline]
 __kasan_slab_free+0x5c/0x80 mm/kasan/common.c:285
 kasan_slab_free include/linux/kasan.h:235 [inline]
 slab_free_hook mm/slub.c:2692 [inline]
 slab_free mm/slub.c:6143 [inline]
 kfree+0x1c1/0x630 mm/slub.c:6461
 slab_free_after_rcu_debug+0x5e/0x220 mm/slub.c:6195
 rcu_do_batch kernel/rcu/tree.c:2617 [inline]
 rcu_core+0x7cd/0x1070 kernel/rcu/tree.c:2869
 handle_softirqs+0x22a/0x870 kernel/softirq.c:622
 __do_softirq kernel/softirq.c:656 [inline]
 invoke_softirq kernel/softirq.c:496 [inline]
 __irq_exit_rcu+0x5f/0x150 kernel/softirq.c:723
 irq_exit_rcu+0x9/0x30 kernel/softirq.c:739
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1056 [inline]
 sysvec_apic_timer_interrupt+0xa6/0xc0 arch/x86/kernel/apic/apic.c:1056
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697

Last potentially related work creation:
 kasan_save_stack+0x3e/0x60 mm/kasan/common.c:57
 kasan_record_aux_stack+0xbd/0xd0 mm/kasan/generic.c:556
 __call_rcu_common kernel/rcu/tree.c:3131 [inline]
 call_rcu+0xee/0x890 kernel/rcu/tree.c:3251
 slab_free_hook mm/slub.c:2656 [inline]
 slab_free mm/slub.c:6143 [inline]
 kmem_cache_free+0x439/0x630 mm/slub.c:6273
 anon_vma_free mm/rmap.c:137 [inline]
 __put_anon_vma+0x12b/0x2d0 mm/rmap.c:2889
 put_anon_vma mm/internal.h:215 [inline]
 unlink_anon_vmas+0x58b/0x730 mm/rmap.c:529
 free_pgtables+0x663/0xb70 mm/memory.c:414
 exit_mmap+0x490/0xa10 mm/mmap.c:1314
 __mmput+0x118/0x430 kernel/fork.c:1174
 exec_mmap+0x3b4/0x440 fs/exec.c:893
 begin_new_exec+0x134a/0x24a0 fs/exec.c:1148
 load_elf_binary+0xa47/0x2980 fs/binfmt_elf.c:1011
 search_binary_handler fs/exec.c:1664 [inline]
 exec_binprm fs/exec.c:1696 [inline]
 bprm_execve+0x93d/0x1460 fs/exec.c:1748
 do_execveat_common+0x50d/0x690 fs/exec.c:1846
 __do_sys_execve fs/exec.c:1930 [inline]
 __se_sys_execve fs/exec.c:1924 [inline]
 __x64_sys_execve+0x97/0xc0 fs/exec.c:1924
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

The buggy address belongs to the object at ffff88816c2f9000
 which belongs to the cache kmalloc-32 of size 32
The buggy address is located 0 bytes inside of
 freed 32-byte region [ffff88816c2f9000, ffff88816c2f9020)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x16c2f9
flags: 0x57ff00000000000(node=1|zone=2|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 057ff00000000000 ffff888100041780 dead000000000100 dead000000000122
raw: 0000000000000000 0000000800400040 00000000f5000000 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 0, migratetype Unmovable, gfp_mask 0xd2cc0(GFP_KERNEL|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 5807, tgid 5807 (sshd), ts 57508476883, free_ts 57508008939
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x231/0x280 mm/page_alloc.c:1889
 prep_new_page mm/page_alloc.c:1897 [inline]
 get_page_from_freelist+0x24dc/0x2580 mm/page_alloc.c:3962
 __alloc_frozen_pages_noprof+0x18d/0x380 mm/page_alloc.c:5250
 alloc_slab_page mm/slub.c:3269 [inline]
 allocate_slab+0x77/0x660 mm/slub.c:3458
 new_slab mm/slub.c:3516 [inline]
 refill_objects+0x331/0x3c0 mm/slub.c:7153
 refill_sheaf mm/slub.c:2818 [inline]
 __pcs_replace_empty_main+0x2b9/0x620 mm/slub.c:4592
 alloc_from_pcs mm/slub.c:4695 [inline]
 slab_alloc_node mm/slub.c:4829 [inline]
 __do_kmalloc_node mm/slub.c:5237 [inline]
 __kvmalloc_node_noprof+0x657/0x8a0 mm/slub.c:6730
 proc_sys_call_handler+0x3d1/0x830 fs/proc/proc_sysctl.c:583
 new_sync_read fs/read_write.c:493 [inline]
 vfs_read+0x582/0xa70 fs/read_write.c:574
 ksys_read+0x150/0x270 fs/read_write.c:717
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
page last free pid 5807 tgid 5807 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 __free_pages_prepare mm/page_alloc.c:1433 [inline]
 __free_frozen_pages+0xc2b/0xdb0 mm/page_alloc.c:2978
 tlb_batch_list_free mm/mmu_gather.c:161 [inline]
 tlb_finish_mmu+0x144/0x230 mm/mmu_gather.c:533
 unmap_region+0x2a5/0x330 mm/vma.c:488
 vms_clear_ptes mm/vma.c:1284 [inline]
 vms_complete_munmap_vmas+0x493/0xc60 mm/vma.c:1326
 do_vmi_align_munmap+0x3b7/0x4b0 mm/vma.c:1585
 do_vmi_munmap+0x252/0x2d0 mm/vma.c:1633
 __vm_munmap+0x22c/0x3d0 mm/vma.c:3254
 __do_sys_munmap mm/mmap.c:1078 [inline]
 __se_sys_munmap mm/mmap.c:1075 [inline]
 __x64_sys_munmap+0x60/0x70 mm/mmap.c:1075
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Memory state around the buggy address:
 ffff88816c2f8f00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff88816c2f8f80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff88816c2f9000: fa fb fb fb fc fc fc fc fa fb fb fb fc fc fc fc
                   ^
 ffff88816c2f9080: fa fb fb fb fc fc fc fc fa fb fb fb fc fc fc fc
 ffff88816c2f9100: fa fb fb fb fc fc fc fc fa fb fb fb fc fc fc fc
==================================================================


***

KASAN: slab-use-after-free Read in ext4_xattr_set_entry

tree:      torvalds
URL:       https://kernel.googlesource.com/pub/scm/linux/kernel/git/torvalds/linux
base:      11439c4635edd669ae435eec308f4ab8a0804808
arch:      amd64
compiler:  Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8
config:    https://ci.syzbot.org/builds/330c6289-adc9-452b-b12f-000d32045593/config
syz repro: https://ci.syzbot.org/findings/703aaa0c-3de2-4301-b1d3-6310fbf18b70/syz_repro

==================================================================
BUG: KASAN: slab-use-after-free in ext4_xattr_set_entry+0x179e/0x1e20 fs/ext4/xattr.c:1740
Read of size 260 at addr ffff88811a37e000 by task syz.2.19/5991

CPU: 0 UID: 0 PID: 5991 Comm: syz.2.19 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:378 [inline]
 print_report+0xba/0x230 mm/kasan/report.c:482
 kasan_report+0x117/0x150 mm/kasan/report.c:595
 check_region_inline mm/kasan/generic.c:-1 [inline]
 kasan_check_range+0x264/0x2c0 mm/kasan/generic.c:200
 __asan_memmove+0x29/0x70 mm/kasan/shadow.c:94
 ext4_xattr_set_entry+0x179e/0x1e20 fs/ext4/xattr.c:1740
 ext4_xattr_block_set+0x636/0x2b00 fs/ext4/xattr.c:1961
 ext4_xattr_set_handle+0xdc2/0x14d0 fs/ext4/xattr.c:2432
 ext4_xattr_set+0x255/0x340 fs/ext4/xattr.c:2560
 __vfs_removexattr+0x431/0x470 fs/xattr.c:518
 __vfs_removexattr_locked+0xe2/0x280 fs/xattr.c:553
 vfs_removexattr+0x7f/0x230 fs/xattr.c:575
 ovl_do_removexattr fs/overlayfs/overlayfs.h:335 [inline]
 ovl_removexattr fs/overlayfs/overlayfs.h:343 [inline]
 ovl_make_workdir fs/overlayfs/super.c:760 [inline]
 ovl_get_workdir fs/overlayfs/super.c:840 [inline]
 ovl_fill_super_creds fs/overlayfs/super.c:1453 [inline]
 ovl_fill_super+0x4c09/0x5e00 fs/overlayfs/super.c:1564
 vfs_get_super fs/super.c:1327 [inline]
 get_tree_nodev+0xbb/0x150 fs/super.c:1346
 vfs_get_tree+0x92/0x2a0 fs/super.c:1754
 fc_mount fs/namespace.c:1193 [inline]
 do_new_mount_fc fs/namespace.c:3763 [inline]
 do_new_mount+0x341/0xd30 fs/namespace.c:3839
 do_mount fs/namespace.c:4172 [inline]
 __do_sys_mount fs/namespace.c:4361 [inline]
 __se_sys_mount+0x31d/0x420 fs/namespace.c:4338
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7facfdf9c799
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007facfd5fe028 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007facfe215fa0 RCX: 00007facfdf9c799
RDX: 0000200000000440 RSI: 0000200000000100 RDI: 0000000000000000
RBP: 00007facfe032bd9 R08: 0000200000000280 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007facfe216038 R14: 00007facfe215fa0 R15: 00007ffdb6825fe8
 </TASK>

Allocated by task 5825:
 kasan_save_stack mm/kasan/common.c:57 [inline]
 kasan_save_track+0x3e/0x80 mm/kasan/common.c:78
 unpoison_slab_object mm/kasan/common.c:340 [inline]
 __kasan_slab_alloc+0x6c/0x80 mm/kasan/common.c:366
 kasan_slab_alloc include/linux/kasan.h:253 [inline]
 slab_post_alloc_hook mm/slub.c:4515 [inline]
 slab_alloc_node mm/slub.c:4844 [inline]
 kmem_cache_alloc_noprof+0x2bc/0x650 mm/slub.c:4851
 __kernfs_new_node+0xe9/0x8e0 fs/kernfs/dir.c:637
 kernfs_new_node+0x102/0x210 fs/kernfs/dir.c:718
 __kernfs_create_file+0x4b/0x2e0 fs/kernfs/file.c:1057
 sysfs_add_file_mode_ns+0x238/0x300 fs/sysfs/file.c:313
 create_files fs/sysfs/group.c:82 [inline]
 internal_create_group+0x673/0x1180 fs/sysfs/group.c:189
 internal_create_groups fs/sysfs/group.c:229 [inline]
 sysfs_create_groups+0x59/0x120 fs/sysfs/group.c:255
 device_add_groups drivers/base/core.c:2836 [inline]
 device_add_attrs+0xdd/0x5b0 drivers/base/core.c:2900
 device_add+0x496/0xb70 drivers/base/core.c:3643
 netdev_register_kobject+0x178/0x310 net/core/net-sysfs.c:2358
 register_netdevice+0x12c0/0x1cf0 net/core/dev.c:11422
 __ip_tunnel_create+0x3e8/0x560 net/ipv4/ip_tunnel.c:268
 ip_tunnel_init_net+0x2e7/0x840 net/ipv4/ip_tunnel.c:1147
 ops_init+0x35c/0x5c0 net/core/net_namespace.c:137
 setup_net+0x118/0x340 net/core/net_namespace.c:446
 copy_net_ns+0x50e/0x730 net/core/net_namespace.c:581
 create_new_namespaces+0x3e7/0x6a0 kernel/nsproxy.c:130
 unshare_nsproxy_namespaces+0x11a/0x160 kernel/nsproxy.c:226
 ksys_unshare+0x51d/0x930 kernel/fork.c:3174
 __do_sys_unshare kernel/fork.c:3245 [inline]
 __se_sys_unshare kernel/fork.c:3243 [inline]
 __x64_sys_unshare+0x38/0x50 kernel/fork.c:3243
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Freed by task 15:
 kasan_save_stack mm/kasan/common.c:57 [inline]
 kasan_save_track+0x3e/0x80 mm/kasan/common.c:78
 kasan_save_free_info+0x46/0x50 mm/kasan/generic.c:584
 poison_slab_object mm/kasan/common.c:253 [inline]
 __kasan_slab_free+0x5c/0x80 mm/kasan/common.c:285
 kasan_slab_free include/linux/kasan.h:235 [inline]
 slab_free_hook mm/slub.c:2692 [inline]
 slab_free mm/slub.c:6143 [inline]
 kmem_cache_free+0x187/0x630 mm/slub.c:6273
 rcu_do_batch kernel/rcu/tree.c:2617 [inline]
 rcu_core+0x7cd/0x1070 kernel/rcu/tree.c:2869
 handle_softirqs+0x22a/0x870 kernel/softirq.c:622
 run_ksoftirqd+0x36/0x60 kernel/softirq.c:1063
 smpboot_thread_fn+0x541/0xa50 kernel/smpboot.c:160
 kthread+0x388/0x470 kernel/kthread.c:467
 ret_from_fork+0x51e/0xb90 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

Last potentially related work creation:
 kasan_save_stack+0x3e/0x60 mm/kasan/common.c:57
 kasan_record_aux_stack+0xbd/0xd0 mm/kasan/generic.c:556
 __call_rcu_common kernel/rcu/tree.c:3131 [inline]
 call_rcu+0xee/0x890 kernel/rcu/tree.c:3251
 kernfs_put+0x18e/0x470 fs/kernfs/dir.c:591
 kernfs_remove_by_name_ns+0xb7/0x130 fs/kernfs/dir.c:1723
 kernfs_remove_by_name include/linux/kernfs.h:633 [inline]
 remove_files fs/sysfs/group.c:28 [inline]
 sysfs_remove_group+0xfc/0x2e0 fs/sysfs/group.c:328
 sysfs_remove_groups+0x54/0xb0 fs/sysfs/group.c:352
 device_remove_groups drivers/base/core.c:2843 [inline]
 device_remove_attrs+0x229/0x280 drivers/base/core.c:2979
 device_del+0x51f/0x8f0 drivers/base/core.c:3877
 unregister_netdevice_many_notify+0x1e0e/0x2370 net/core/dev.c:12447
 ops_exit_rtnl_list net/core/net_namespace.c:187 [inline]
 ops_undo_list+0x3d3/0x940 net/core/net_namespace.c:248
 cleanup_net+0x56b/0x800 net/core/net_namespace.c:704
 process_one_work kernel/workqueue.c:3275 [inline]
 process_scheduled_works+0xb02/0x1830 kernel/workqueue.c:3358
 worker_thread+0xa50/0xfc0 kernel/workqueue.c:3439
 kthread+0x388/0x470 kernel/kthread.c:467
 ret_from_fork+0x51e/0xb90 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

The buggy address belongs to the object at ffff88811a37e000
 which belongs to the cache kernfs_node_cache of size 176
The buggy address is located 0 bytes inside of
 freed 176-byte region [ffff88811a37e000, ffff88811a37e0b0)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0xffff88811a37ee10 pfn:0x11a37e
flags: 0x17ff00000000200(workingset|node=0|zone=2|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 017ff00000000200 ffff8881012d3dc0 ffffea000468fed0 ffffea000468df10
raw: ffff88811a37ee10 000000080011000a 00000000f5000000 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 0, migratetype Unmovable, gfp_mask 0xd2cc0(GFP_KERNEL|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 5822, tgid 5822 (syz-executor), ts 67128981798, free_ts 62919905097
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x231/0x280 mm/page_alloc.c:1889
 prep_new_page mm/page_alloc.c:1897 [inline]
 get_page_from_freelist+0x24dc/0x2580 mm/page_alloc.c:3962
 __alloc_frozen_pages_noprof+0x18d/0x380 mm/page_alloc.c:5250
 alloc_slab_page mm/slub.c:3269 [inline]
 allocate_slab+0x77/0x660 mm/slub.c:3458
 new_slab mm/slub.c:3516 [inline]
 refill_objects+0x331/0x3c0 mm/slub.c:7153
 refill_sheaf mm/slub.c:2818 [inline]
 __pcs_replace_empty_main+0x2b9/0x620 mm/slub.c:4592
 alloc_from_pcs mm/slub.c:4695 [inline]
 slab_alloc_node mm/slub.c:4829 [inline]
 kmem_cache_alloc_noprof+0x37d/0x650 mm/slub.c:4851
 __kernfs_new_node+0xe9/0x8e0 fs/kernfs/dir.c:637
 kernfs_new_node+0x102/0x210 fs/kernfs/dir.c:718
 __kernfs_create_file+0x4b/0x2e0 fs/kernfs/file.c:1057
 sysfs_add_file_mode_ns+0x238/0x300 fs/sysfs/file.c:313
 create_files fs/sysfs/group.c:82 [inline]
 internal_create_group+0x673/0x1180 fs/sysfs/group.c:189
 internal_create_groups fs/sysfs/group.c:229 [inline]
 sysfs_create_groups+0x59/0x120 fs/sysfs/group.c:255
 device_add_groups drivers/base/core.c:2836 [inline]
 device_add_attrs+0x1bf/0x5b0 drivers/base/core.c:2911
 device_add+0x496/0xb70 drivers/base/core.c:3643
 netdev_register_kobject+0x178/0x310 net/core/net-sysfs.c:2358
page last free pid 5809 tgid 5809 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 __free_pages_prepare mm/page_alloc.c:1433 [inline]
 __free_frozen_pages+0xc2b/0xdb0 mm/page_alloc.c:2978
 vfree+0x25a/0x400 mm/vmalloc.c:3479
 kcov_put kernel/kcov.c:442 [inline]
 kcov_close+0x28/0x50 kernel/kcov.c:543
 __fput+0x44f/0xa70 fs/file_table.c:469
 fput_close_sync+0x11f/0x240 fs/file_table.c:574
 __do_sys_close fs/open.c:1509 [inline]
 __se_sys_close fs/open.c:1494 [inline]
 __x64_sys_close+0x7e/0x110 fs/open.c:1494
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Memory state around the buggy address:
 ffff88811a37df00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff88811a37df80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff88811a37e000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                   ^
 ffff88811a37e080: fb fb fb fb fb fb fc fc fc fc fc fc fc fc fa fb
 ffff88811a37e100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================


***

KASAN: use-after-free Read in ext4_xattr_block_csum_set

tree:      torvalds
URL:       https://kernel.googlesource.com/pub/scm/linux/kernel/git/torvalds/linux
base:      11439c4635edd669ae435eec308f4ab8a0804808
arch:      amd64
compiler:  Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8
config:    https://ci.syzbot.org/builds/330c6289-adc9-452b-b12f-000d32045593/config
C repro:   https://ci.syzbot.org/findings/e7360798-7b84-42ba-9afb-319d10454142/c_repro
syz repro: https://ci.syzbot.org/findings/e7360798-7b84-42ba-9afb-319d10454142/syz_repro

fscrypt: AES-256-CBC-CTS using implementation "cts(cbc(ecb(aes-lib)))"
fscrypt: AES-256-XTS using implementation "xts(ecb(aes-lib))"
==================================================================
BUG: KASAN: use-after-free in crc32c_base lib/crc/crc32-main.c:54 [inline]
BUG: KASAN: use-after-free in crc32c_arch lib/crc/x86/crc32.h:44 [inline]
BUG: KASAN: use-after-free in crc32c+0x3cc/0x470 lib/crc/crc32-main.c:86
Read of size 1 at addr ffff88811f068000 by task syz.0.17/5956

CPU: 0 UID: 0 PID: 5956 Comm: syz.0.17 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:378 [inline]
 print_report+0xba/0x230 mm/kasan/report.c:482
 kasan_report+0x117/0x150 mm/kasan/report.c:595
 crc32c_base lib/crc/crc32-main.c:54 [inline]
 crc32c_arch lib/crc/x86/crc32.h:44 [inline]
 crc32c+0x3cc/0x470 lib/crc/crc32-main.c:86
 ext4_chksum fs/ext4/ext4.h:2553 [inline]
 ext4_xattr_block_csum fs/ext4/xattr.c:147 [inline]
 ext4_xattr_block_csum_set+0x241/0x330 fs/ext4/xattr.c:172
 ext4_xattr_block_set+0x2494/0x2b00 fs/ext4/xattr.c:2165
 ext4_xattr_set_handle+0xe37/0x14d0 fs/ext4/xattr.c:2458
 ext4_set_context+0x233/0x560 fs/ext4/crypto.c:166
 fscrypt_set_context+0x397/0x460 fs/crypto/policy.c:791
 __ext4_new_inode+0x3158/0x3d20 fs/ext4/ialloc.c:1314
 ext4_create+0x233/0x470 fs/ext4/namei.c:2820
 lookup_open fs/namei.c:4483 [inline]
 open_last_lookups fs/namei.c:4583 [inline]
 path_openat+0x1395/0x3860 fs/namei.c:4827
 do_file_open+0x23e/0x4a0 fs/namei.c:4859
 do_sys_openat2+0x113/0x200 fs/open.c:1366
 do_sys_open fs/open.c:1372 [inline]
 __do_sys_openat fs/open.c:1388 [inline]
 __se_sys_openat fs/open.c:1383 [inline]
 __x64_sys_openat+0x138/0x170 fs/open.c:1383
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fb6f179c799
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fb6f26cf028 EFLAGS: 00000246 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 00007fb6f1a15fa0 RCX: 00007fb6f179c799
RDX: 0000000000101042 RSI: 00002000000002c0 RDI: ffffffffffffff9c
RBP: 00007fb6f1832bd9 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000040 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fb6f1a16038 R14: 00007fb6f1a15fa0 R15: 00007ffe4cb28f88
 </TASK>

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0xc1 pfn:0x11f068
flags: 0x17ff00000000000(node=0|zone=2|lastcpupid=0x7ff)
raw: 017ff00000000000 ffffea00047c0f08 ffffea00047c1648 0000000000000000
raw: 00000000000000c1 0000000000000000 00000000ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as freed
page last allocated via order 0, migratetype Movable, gfp_mask 0x140cca(GFP_HIGHUSER_MOVABLE|__GFP_COMP), pid 5966, tgid 5966 (modprobe), ts 74332946165, free_ts 74344928310
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x231/0x280 mm/page_alloc.c:1889
 prep_new_page mm/page_alloc.c:1897 [inline]
 get_page_from_freelist+0x24dc/0x2580 mm/page_alloc.c:3962
 __alloc_frozen_pages_noprof+0x18d/0x380 mm/page_alloc.c:5250
 alloc_pages_mpol+0x232/0x4a0 mm/mempolicy.c:2484
 folio_alloc_mpol_noprof mm/mempolicy.c:2503 [inline]
 vma_alloc_folio_noprof+0xea/0x210 mm/mempolicy.c:2538
 folio_prealloc mm/memory.c:-1 [inline]
 do_cow_fault mm/memory.c:5822 [inline]
 do_fault mm/memory.c:5934 [inline]
 do_pte_missing+0x4ea/0x3750 mm/memory.c:4477
 handle_pte_fault mm/memory.c:6316 [inline]
 __handle_mm_fault mm/memory.c:6454 [inline]
 handle_mm_fault+0x1bec/0x3310 mm/memory.c:6623
 do_user_addr_fault+0xa73/0x1340 arch/x86/mm/fault.c:1334
 handle_page_fault arch/x86/mm/fault.c:1474 [inline]
 exc_page_fault+0x6a/0xc0 arch/x86/mm/fault.c:1527
 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:618
page last free pid 5966 tgid 5966 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 __free_pages_prepare mm/page_alloc.c:1433 [inline]
 free_unref_folios+0xed5/0x16d0 mm/page_alloc.c:3040
 folios_put_refs+0x789/0x8d0 mm/swap.c:1002
 free_pages_and_swap_cache+0x2e7/0x5b0 mm/swap_state.c:423
 __tlb_batch_free_encoded_pages mm/mmu_gather.c:138 [inline]
 tlb_batch_pages_flush mm/mmu_gather.c:151 [inline]
 tlb_flush_mmu_free mm/mmu_gather.c:398 [inline]
 tlb_flush_mmu+0x6d3/0xa30 mm/mmu_gather.c:405
 tlb_finish_mmu+0xf9/0x230 mm/mmu_gather.c:530
 exit_mmap+0x498/0xa10 mm/mmap.c:1315
 __mmput+0x118/0x430 kernel/fork.c:1174
 exit_mm+0x168/0x220 kernel/exit.c:581
 do_exit+0x62e/0x2320 kernel/exit.c:959
 do_group_exit+0x21b/0x2d0 kernel/exit.c:1112
 __do_sys_exit_group kernel/exit.c:1123 [inline]
 __se_sys_exit_group kernel/exit.c:1121 [inline]
 __x64_sys_exit_group+0x3f/0x40 kernel/exit.c:1121
 x64_sys_call+0x221a/0x2240 arch/x86/include/generated/asm/syscalls_64.h:232
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Memory state around the buggy address:
 ffff88811f067f00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff88811f067f80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff88811f068000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                   ^
 ffff88811f068080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff88811f068100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
==================================================================


***

KASAN: use-after-free Read in ext4_xattr_set_entry

tree:      torvalds
URL:       https://kernel.googlesource.com/pub/scm/linux/kernel/git/torvalds/linux
base:      11439c4635edd669ae435eec308f4ab8a0804808
arch:      amd64
compiler:  Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8
config:    https://ci.syzbot.org/builds/330c6289-adc9-452b-b12f-000d32045593/config
C repro:   https://ci.syzbot.org/findings/f2e1c927-88dd-48df-af44-6348bc760ced/c_repro
syz repro: https://ci.syzbot.org/findings/f2e1c927-88dd-48df-af44-6348bc760ced/syz_repro

EXT4-fs (loop0): mounted filesystem 00000000-0000-0000-0000-000000000000 r/w without journal. Quota mode: none.
ext4 filesystem being mounted at /0/file0 supports timestamps until 2038-01-19 (0x7fffffff)
==================================================================
BUG: KASAN: use-after-free in ext4_xattr_set_entry+0x179e/0x1e20 fs/ext4/xattr.c:1740
Read of size 260 at addr ffff88811cde4000 by task syz.0.17/5956

CPU: 0 UID: 0 PID: 5956 Comm: syz.0.17 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:378 [inline]
 print_report+0xba/0x230 mm/kasan/report.c:482
 kasan_report+0x117/0x150 mm/kasan/report.c:595
 check_region_inline mm/kasan/generic.c:-1 [inline]
 kasan_check_range+0x264/0x2c0 mm/kasan/generic.c:200
 __asan_memmove+0x29/0x70 mm/kasan/shadow.c:94
 ext4_xattr_set_entry+0x179e/0x1e20 fs/ext4/xattr.c:1740
 ext4_xattr_block_set+0x636/0x2b00 fs/ext4/xattr.c:1961
 ext4_xattr_set_handle+0xdc2/0x14d0 fs/ext4/xattr.c:2432
 ext4_xattr_set+0x255/0x340 fs/ext4/xattr.c:2560
 __vfs_removexattr+0x431/0x470 fs/xattr.c:518
 __vfs_removexattr_locked+0xe2/0x280 fs/xattr.c:553
 vfs_removexattr+0x7f/0x230 fs/xattr.c:575
 ovl_do_removexattr fs/overlayfs/overlayfs.h:335 [inline]
 ovl_removexattr fs/overlayfs/overlayfs.h:343 [inline]
 ovl_make_workdir fs/overlayfs/super.c:760 [inline]
 ovl_get_workdir fs/overlayfs/super.c:840 [inline]
 ovl_fill_super_creds fs/overlayfs/super.c:1453 [inline]
 ovl_fill_super+0x4c09/0x5e00 fs/overlayfs/super.c:1564
 vfs_get_super fs/super.c:1327 [inline]
 get_tree_nodev+0xbb/0x150 fs/super.c:1346
 vfs_get_tree+0x92/0x2a0 fs/super.c:1754
 fc_mount fs/namespace.c:1193 [inline]
 do_new_mount_fc fs/namespace.c:3763 [inline]
 do_new_mount+0x341/0xd30 fs/namespace.c:3839
 do_mount fs/namespace.c:4172 [inline]
 __do_sys_mount fs/namespace.c:4361 [inline]
 __se_sys_mount+0x31d/0x420 fs/namespace.c:4338
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f60b0d9c799
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffcaa4270a8 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007f60b1015fa0 RCX: 00007f60b0d9c799
RDX: 0000200000000b80 RSI: 0000200000000000 RDI: 0000000000000000
RBP: 00007f60b0e32bd9 R08: 0000200000000100 R09: 0000000000000000
R10: 0000000000000804 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f60b1015fac R14: 00007f60b1015fa0 R15: 00007f60b1015fa0
 </TASK>

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x39c pfn:0x11cde4
flags: 0x17ff00000000000(node=0|zone=2|lastcpupid=0x7ff)
raw: 017ff00000000000 ffffea0004737948 ffff888121040d70 0000000000000000
raw: 000000000000039c 0000000000000000 00000000ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as freed
page last allocated via order 0, migratetype Movable, gfp_mask 0x140cca(GFP_HIGHUSER_MOVABLE|__GFP_COMP), pid 5919, tgid 5919 (syz-executor), ts 71335198059, free_ts 71626869117
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x231/0x280 mm/page_alloc.c:1889
 prep_new_page mm/page_alloc.c:1897 [inline]
 get_page_from_freelist+0x24dc/0x2580 mm/page_alloc.c:3962
 __alloc_frozen_pages_noprof+0x18d/0x380 mm/page_alloc.c:5250
 alloc_pages_mpol+0x232/0x4a0 mm/mempolicy.c:2484
 folio_alloc_mpol_noprof mm/mempolicy.c:2503 [inline]
 vma_alloc_folio_noprof+0xea/0x210 mm/mempolicy.c:2538
 folio_prealloc mm/memory.c:-1 [inline]
 do_cow_fault mm/memory.c:5822 [inline]
 do_fault mm/memory.c:5934 [inline]
 do_pte_missing+0x4ea/0x3750 mm/memory.c:4477
 handle_pte_fault mm/memory.c:6316 [inline]
 __handle_mm_fault mm/memory.c:6454 [inline]
 handle_mm_fault+0x1bec/0x3310 mm/memory.c:6623
 do_user_addr_fault+0xa73/0x1340 arch/x86/mm/fault.c:1334
 handle_page_fault arch/x86/mm/fault.c:1474 [inline]
 exc_page_fault+0x6a/0xc0 arch/x86/mm/fault.c:1527
 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:618
page last free pid 5920 tgid 5920 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 __free_pages_prepare mm/page_alloc.c:1433 [inline]
 free_unref_folios+0xed5/0x16d0 mm/page_alloc.c:3040
 folios_put_refs+0x789/0x8d0 mm/swap.c:1002
 free_pages_and_swap_cache+0x537/0x5b0 mm/swap_state.c:426
 __tlb_batch_free_encoded_pages mm/mmu_gather.c:138 [inline]
 tlb_batch_pages_flush mm/mmu_gather.c:151 [inline]
 tlb_flush_mmu_free mm/mmu_gather.c:398 [inline]
 tlb_flush_mmu+0x6d3/0xa30 mm/mmu_gather.c:405
 tlb_finish_mmu+0xf9/0x230 mm/mmu_gather.c:530
 exit_mmap+0x498/0xa10 mm/mmap.c:1315
 __mmput+0x118/0x430 kernel/fork.c:1174
 exit_mm+0x168/0x220 kernel/exit.c:581
 do_exit+0x62e/0x2320 kernel/exit.c:959
 do_group_exit+0x21b/0x2d0 kernel/exit.c:1112
 get_signal+0x1284/0x1330 kernel/signal.c:3034
 arch_do_signal_or_restart+0xbc/0x830 arch/x86/kernel/signal.c:337
 __exit_to_user_mode_loop kernel/entry/common.c:64 [inline]
 exit_to_user_mode_loop+0x86/0x480 kernel/entry/common.c:98
 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:226 [inline]
 syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:256 [inline]
 syscall_exit_to_user_mode include/linux/entry-common.h:325 [inline]
 do_syscall_64+0x32d/0xf80 arch/x86/entry/syscall_64.c:100
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Memory state around the buggy address:
 ffff88811cde3f00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff88811cde3f80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff88811cde4000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                   ^
 ffff88811cde4080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff88811cde4100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
==================================================================


***

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  Tested-by: syzbot@syzkaller.appspotmail.com

---
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Thread overview: 6+ messages (download: mbox.gz follow: Atom feed
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2026-03-01 14:55 [moderation/CI] Re: ext4: avoid infinite loops caused by data conflicts syzbot ci
2026-03-02 10:50 ` Pimyn Girgis
2026-03-02 14:07 ` Aleksandr Nogikh
2026-03-02 14:09   ` syzbot ci
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2026-03-02 19:01 syzbot ci
2026-03-03  7:46 ` Pimyn Girgis

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