Re: [moderation/CI] Re: ext4: avoid infinite loops caused by data conflicts

Pimyn Girgis
2026-03-03T07:46:15Z

#syz upstream

On Mon, Mar 2, 2026 at 8:01 PM syzbot ci
<syzbot+ciab2b683878a46188@syzkaller.appspotmail.com> wrote:
>
> 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
> ==================================================================
>
>
> ***
>
> 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@lists.linux.dev 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
>
> --
> You received this message because you are subscribed to the Google Groups "syzkaller-upstream-moderation" group.
> To unsubscribe from this group and stop receiving emails from it, send an email to syzkaller-upstream-moderation+unsubscribe@googlegroups.com.
> To view this discussion visit https://groups.google.com/d/msgid/syzkaller-upstream-moderation/69a5de85.a70a0220.b118c.0002.GAE%40google.com.