[syzbot] [ext4?] KASAN: out-of-bounds Read in ext4_xattr_set_entry

[syzbot] [ext4?] KASAN: out-of-bounds Read in ext4_xattr_set_entry

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit:    a940d9a43e62 Merge tag 'soc-arm-6.12' of git://git.kernel...
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=16689207980000
kernel config:  https://syzkaller.appspot.com/x/.config?x=1653f803fffa3848
dashboard link: https://syzkaller.appspot.com/bug?extid=f792df426ff0f5ceb8d1
compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=11689207980000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=104d469f980000

Downloadable assets:
disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/7bc7510fe41f/non_bootable_disk-a940d9a4.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/371e11b6a9e5/vmlinux-a940d9a4.xz
kernel image: https://storage.googleapis.com/syzbot-assets/920eb0c53785/bzImage-a940d9a4.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/4146c0b2e744/mount_0.gz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+f792df426ff0f5ceb8d1@syzkaller.appspotmail.com

EXT4-fs (loop0): 1 truncate cleaned up
EXT4-fs (loop0): mounted filesystem 00000000-0000-0000-0000-000000000000 r/w without journal. Quota mode: writeback.
==================================================================
BUG: KASAN: out-of-bounds in ext4_xattr_set_entry+0x8ce/0x1f60 fs/ext4/xattr.c:1781
Read of size 18446744073709551572 at addr ffff888036426850 by task syz-executor264/5095

CPU: 0 UID: 0 PID: 5095 Comm: syz-executor264 Not tainted 6.11.0-syzkaller-03917-ga940d9a43e62 #0
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:93 [inline]
 dump_stack_lvl+0x241/0x360 lib/dump_stack.c:119
 print_address_description mm/kasan/report.c:377 [inline]
 print_report+0x169/0x550 mm/kasan/report.c:488
 kasan_report+0x143/0x180 mm/kasan/report.c:601
 kasan_check_range+0x282/0x290 mm/kasan/generic.c:189
 __asan_memmove+0x29/0x70 mm/kasan/shadow.c:94
 ext4_xattr_set_entry+0x8ce/0x1f60 fs/ext4/xattr.c:1781
 ext4_xattr_block_set+0xa39/0x3980 fs/ext4/xattr.c:2028
 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+0x12d7/0x1cf0 fs/ext4/xattr.c:2836
 __ext4_expand_extra_isize+0x2fb/0x3e0 fs/ext4/inode.c:5858
 ext4_try_to_expand_extra_isize fs/ext4/inode.c:5901 [inline]
 __ext4_mark_inode_dirty+0x524/0x880 fs/ext4/inode.c:5979
 __ext4_unlink+0x6c2/0xb50 fs/ext4/namei.c:3289
 ext4_unlink+0x1bf/0x5a0 fs/ext4/namei.c:3318
 vfs_unlink+0x365/0x650 fs/namei.c:4469
 do_unlinkat+0x4ae/0x830 fs/namei.c:4533
 __do_sys_unlink fs/namei.c:4581 [inline]
 __se_sys_unlink fs/namei.c:4579 [inline]
 __x64_sys_unlink+0x47/0x50 fs/namei.c:4579
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f2549cabe99
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 f1 17 00 00 90 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 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fff914df8a8 EFLAGS: 00000246 ORIG_RAX: 0000000000000057
RAX: ffffffffffffffda RBX: 0031656c69662f2e RCX: 00007f2549cabe99
RDX: 00007f2549cabe99 RSI: 00007f2549cabe99 RDI: 0000000020000180
RBP: 0032656c69662f2e R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007fff914df8e0
R13: 00007fff914dfb08 R14: 431bde82d7b634db R15: 00007f2549cf503b
 </TASK>

Allocated by task 5095:
 kasan_save_stack mm/kasan/common.c:47 [inline]
 kasan_save_track+0x3f/0x80 mm/kasan/common.c:68
 poison_kmalloc_redzone mm/kasan/common.c:370 [inline]
 __kasan_kmalloc+0x98/0xb0 mm/kasan/common.c:387
 kasan_kmalloc include/linux/kasan.h:211 [inline]
 __do_kmalloc_node mm/slub.c:4159 [inline]
 __kmalloc_node_track_caller_noprof+0x225/0x440 mm/slub.c:4178
 kmemdup_noprof+0x2a/0x60 mm/util.c:133
 ext4_xattr_block_set+0x88b/0x3980 fs/ext4/xattr.c:1976
 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+0x12d7/0x1cf0 fs/ext4/xattr.c:2836
 __ext4_expand_extra_isize+0x2fb/0x3e0 fs/ext4/inode.c:5858
 ext4_try_to_expand_extra_isize fs/ext4/inode.c:5901 [inline]
 __ext4_mark_inode_dirty+0x524/0x880 fs/ext4/inode.c:5979
 __ext4_unlink+0x6c2/0xb50 fs/ext4/namei.c:3289
 ext4_unlink+0x1bf/0x5a0 fs/ext4/namei.c:3318
 vfs_unlink+0x365/0x650 fs/namei.c:4469
 do_unlinkat+0x4ae/0x830 fs/namei.c:4533
 __do_sys_unlink fs/namei.c:4581 [inline]
 __se_sys_unlink fs/namei.c:4579 [inline]
 __x64_sys_unlink+0x47/0x50 fs/namei.c:4579
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

The buggy address belongs to the object at ffff888036426800
 which belongs to the cache kmalloc-1k of size 1024
The buggy address is located 80 bytes inside of
 1024-byte region [ffff888036426800, ffff888036426c00)

The buggy address belongs to the physical page:
page: refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x36424
head: order:2 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
flags: 0x4fff00000000040(head|node=1|zone=1|lastcpupid=0x7ff)
page_type: 0xfdffffff(slab)
raw: 04fff00000000040 ffff88801ac41dc0 dead000000000100 dead000000000122
raw: 0000000000000000 0000000080080008 00000001fdffffff 0000000000000000
head: 04fff00000000040 ffff88801ac41dc0 dead000000000100 dead000000000122
head: 0000000000000000 0000000080080008 00000001fdffffff 0000000000000000
head: 04fff00000000002 ffffea0000d90901 ffffffffffffffff 0000000000000000
head: 0000000000000004 0000000000000000 00000000ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 2, migratetype Unmovable, gfp_mask 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 5049, tgid 5049 (dhcpcd), ts 74832155643, free_ts 73695396465
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x1f3/0x230 mm/page_alloc.c:1500
 prep_new_page mm/page_alloc.c:1508 [inline]
 get_page_from_freelist+0x2e4c/0x2f10 mm/page_alloc.c:3446
 __alloc_pages_noprof+0x256/0x6c0 mm/page_alloc.c:4702
 __alloc_pages_node_noprof include/linux/gfp.h:269 [inline]
 alloc_pages_node_noprof include/linux/gfp.h:296 [inline]
 alloc_slab_page+0x5f/0x120 mm/slub.c:2319
 allocate_slab+0x5a/0x2f0 mm/slub.c:2482
 new_slab mm/slub.c:2535 [inline]
 ___slab_alloc+0xcd1/0x14b0 mm/slub.c:3721
 __slab_alloc+0x58/0xa0 mm/slub.c:3811
 __slab_alloc_node mm/slub.c:3864 [inline]
 slab_alloc_node mm/slub.c:4026 [inline]
 __do_kmalloc_node mm/slub.c:4158 [inline]
 __kmalloc_noprof+0x25a/0x400 mm/slub.c:4171
 kmalloc_noprof include/linux/slab.h:694 [inline]
 load_elf_phdrs+0x162/0x260 fs/binfmt_elf.c:526
 load_elf_binary+0x920/0x2680 fs/binfmt_elf.c:955
 search_binary_handler fs/exec.c:1820 [inline]
 exec_binprm fs/exec.c:1862 [inline]
 bprm_execve+0xaf8/0x1770 fs/exec.c:1913
 do_execveat_common+0x55f/0x6f0 fs/exec.c:2020
 do_execve fs/exec.c:2094 [inline]
 __do_sys_execve fs/exec.c:2170 [inline]
 __se_sys_execve fs/exec.c:2165 [inline]
 __x64_sys_execve+0x92/0xb0 fs/exec.c:2165
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
page last free pid 5032 tgid 5032 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 free_pages_prepare mm/page_alloc.c:1101 [inline]
 free_unref_page+0xd22/0xea0 mm/page_alloc.c:2619
 __slab_free+0x31b/0x3d0 mm/slub.c:4385
 qlink_free mm/kasan/quarantine.c:163 [inline]
 qlist_free_all+0x9e/0x140 mm/kasan/quarantine.c:179
 kasan_quarantine_reduce+0x14f/0x170 mm/kasan/quarantine.c:286
 __kasan_slab_alloc+0x23/0x80 mm/kasan/common.c:322
 kasan_slab_alloc include/linux/kasan.h:201 [inline]
 slab_post_alloc_hook mm/slub.c:3989 [inline]
 slab_alloc_node mm/slub.c:4038 [inline]
 __do_kmalloc_node mm/slub.c:4158 [inline]
 __kmalloc_noprof+0x1a6/0x400 mm/slub.c:4171
 kmalloc_noprof include/linux/slab.h:694 [inline]
 tomoyo_realpath_from_path+0xcf/0x5e0 security/tomoyo/realpath.c:251
 tomoyo_get_realpath security/tomoyo/file.c:151 [inline]
 tomoyo_path_perm+0x2b7/0x740 security/tomoyo/file.c:822
 security_inode_getattr+0x130/0x330 security/security.c:2371
 vfs_getattr+0x45/0x430 fs/stat.c:204
 vfs_fstat fs/stat.c:229 [inline]
 vfs_fstatat+0xe4/0x190 fs/stat.c:338
 __do_sys_newfstatat fs/stat.c:505 [inline]
 __se_sys_newfstatat fs/stat.c:499 [inline]
 __x64_sys_newfstatat+0x11d/0x1a0 fs/stat.c:499
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Memory state around the buggy address:
 ffff888036426700: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff888036426780: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff888036426800: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
                                                 ^
 ffff888036426880: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff888036426900: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
==================================================================


---
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Re: [syzbot] [ext4?] KASAN: out-of-bounds Read in ext4_xattr_set_entry

[Qianqiang Liu]

On Sat, Sep 21, 2024 at 05:16:22PM -0700, syzbot wrote:
> Hello,
> 
> syzbot found the following issue on:
> 
> HEAD commit:    a940d9a43e62 Merge tag 'soc-arm-6.12' of git://git.kernel...
> git tree:       upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=16689207980000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=1653f803fffa3848
> dashboard link: https://syzkaller.appspot.com/bug?extid=f792df426ff0f5ceb8d1
> compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
> syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=11689207980000
> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=104d469f980000
> 
> Downloadable assets:
> disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/7bc7510fe41f/non_bootable_disk-a940d9a4.raw.xz
> vmlinux: https://storage.googleapis.com/syzbot-assets/371e11b6a9e5/vmlinux-a940d9a4.xz
> kernel image: https://storage.googleapis.com/syzbot-assets/920eb0c53785/bzImage-a940d9a4.xz
> mounted in repro: https://storage.googleapis.com/syzbot-assets/4146c0b2e744/mount_0.gz
> 
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+f792df426ff0f5ceb8d1@syzkaller.appspotmail.com
> 
> EXT4-fs (loop0): 1 truncate cleaned up
> EXT4-fs (loop0): mounted filesystem 00000000-0000-0000-0000-000000000000 r/w without journal. Quota mode: writeback.
> ==================================================================
> BUG: KASAN: out-of-bounds in ext4_xattr_set_entry+0x8ce/0x1f60 fs/ext4/xattr.c:1781
> Read of size 18446744073709551572 at addr ffff888036426850 by task syz-executor264/5095
> 
> CPU: 0 UID: 0 PID: 5095 Comm: syz-executor264 Not tainted 6.11.0-syzkaller-03917-ga940d9a43e62 #0
> Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
> Call Trace:
>  <TASK>
>  __dump_stack lib/dump_stack.c:93 [inline]
>  dump_stack_lvl+0x241/0x360 lib/dump_stack.c:119
>  print_address_description mm/kasan/report.c:377 [inline]
>  print_report+0x169/0x550 mm/kasan/report.c:488
>  kasan_report+0x143/0x180 mm/kasan/report.c:601
>  kasan_check_range+0x282/0x290 mm/kasan/generic.c:189
>  __asan_memmove+0x29/0x70 mm/kasan/shadow.c:94
>  ext4_xattr_set_entry+0x8ce/0x1f60 fs/ext4/xattr.c:1781
>  ext4_xattr_block_set+0xa39/0x3980 fs/ext4/xattr.c:2028
>  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+0x12d7/0x1cf0 fs/ext4/xattr.c:2836
>  __ext4_expand_extra_isize+0x2fb/0x3e0 fs/ext4/inode.c:5858
>  ext4_try_to_expand_extra_isize fs/ext4/inode.c:5901 [inline]
>  __ext4_mark_inode_dirty+0x524/0x880 fs/ext4/inode.c:5979
>  __ext4_unlink+0x6c2/0xb50 fs/ext4/namei.c:3289
>  ext4_unlink+0x1bf/0x5a0 fs/ext4/namei.c:3318
>  vfs_unlink+0x365/0x650 fs/namei.c:4469
>  do_unlinkat+0x4ae/0x830 fs/namei.c:4533
>  __do_sys_unlink fs/namei.c:4581 [inline]
>  __se_sys_unlink fs/namei.c:4579 [inline]
>  __x64_sys_unlink+0x47/0x50 fs/namei.c:4579
>  do_syscall_x64 arch/x86/entry/common.c:52 [inline]
>  do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
>  entry_SYSCALL_64_after_hwframe+0x77/0x7f
> RIP: 0033:0x7f2549cabe99
> Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 f1 17 00 00 90 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 b8 ff ff ff f7 d8 64 89 01 48
> RSP: 002b:00007fff914df8a8 EFLAGS: 00000246 ORIG_RAX: 0000000000000057
> RAX: ffffffffffffffda RBX: 0031656c69662f2e RCX: 00007f2549cabe99
> RDX: 00007f2549cabe99 RSI: 00007f2549cabe99 RDI: 0000000020000180
> RBP: 0032656c69662f2e R08: 0000000000000000 R09: 0000000000000000
> R10: 0000000000000000 R11: 0000000000000246 R12: 00007fff914df8e0
> R13: 00007fff914dfb08 R14: 431bde82d7b634db R15: 00007f2549cf503b
>  </TASK>
> 
> Allocated by task 5095:
>  kasan_save_stack mm/kasan/common.c:47 [inline]
>  kasan_save_track+0x3f/0x80 mm/kasan/common.c:68
>  poison_kmalloc_redzone mm/kasan/common.c:370 [inline]
>  __kasan_kmalloc+0x98/0xb0 mm/kasan/common.c:387
>  kasan_kmalloc include/linux/kasan.h:211 [inline]
>  __do_kmalloc_node mm/slub.c:4159 [inline]
>  __kmalloc_node_track_caller_noprof+0x225/0x440 mm/slub.c:4178
>  kmemdup_noprof+0x2a/0x60 mm/util.c:133
>  ext4_xattr_block_set+0x88b/0x3980 fs/ext4/xattr.c:1976
>  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+0x12d7/0x1cf0 fs/ext4/xattr.c:2836
>  __ext4_expand_extra_isize+0x2fb/0x3e0 fs/ext4/inode.c:5858
>  ext4_try_to_expand_extra_isize fs/ext4/inode.c:5901 [inline]
>  __ext4_mark_inode_dirty+0x524/0x880 fs/ext4/inode.c:5979
>  __ext4_unlink+0x6c2/0xb50 fs/ext4/namei.c:3289
>  ext4_unlink+0x1bf/0x5a0 fs/ext4/namei.c:3318
>  vfs_unlink+0x365/0x650 fs/namei.c:4469
>  do_unlinkat+0x4ae/0x830 fs/namei.c:4533
>  __do_sys_unlink fs/namei.c:4581 [inline]
>  __se_sys_unlink fs/namei.c:4579 [inline]
>  __x64_sys_unlink+0x47/0x50 fs/namei.c:4579
>  do_syscall_x64 arch/x86/entry/common.c:52 [inline]
>  do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
>  entry_SYSCALL_64_after_hwframe+0x77/0x7f
> 
> The buggy address belongs to the object at ffff888036426800
>  which belongs to the cache kmalloc-1k of size 1024
> The buggy address is located 80 bytes inside of
>  1024-byte region [ffff888036426800, ffff888036426c00)
> 
> The buggy address belongs to the physical page:
> page: refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x36424
> head: order:2 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
> flags: 0x4fff00000000040(head|node=1|zone=1|lastcpupid=0x7ff)
> page_type: 0xfdffffff(slab)
> raw: 04fff00000000040 ffff88801ac41dc0 dead000000000100 dead000000000122
> raw: 0000000000000000 0000000080080008 00000001fdffffff 0000000000000000
> head: 04fff00000000040 ffff88801ac41dc0 dead000000000100 dead000000000122
> head: 0000000000000000 0000000080080008 00000001fdffffff 0000000000000000
> head: 04fff00000000002 ffffea0000d90901 ffffffffffffffff 0000000000000000
> head: 0000000000000004 0000000000000000 00000000ffffffff 0000000000000000
> page dumped because: kasan: bad access detected
> page_owner tracks the page as allocated
> page last allocated via order 2, migratetype Unmovable, gfp_mask 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 5049, tgid 5049 (dhcpcd), ts 74832155643, free_ts 73695396465
>  set_page_owner include/linux/page_owner.h:32 [inline]
>  post_alloc_hook+0x1f3/0x230 mm/page_alloc.c:1500
>  prep_new_page mm/page_alloc.c:1508 [inline]
>  get_page_from_freelist+0x2e4c/0x2f10 mm/page_alloc.c:3446
>  __alloc_pages_noprof+0x256/0x6c0 mm/page_alloc.c:4702
>  __alloc_pages_node_noprof include/linux/gfp.h:269 [inline]
>  alloc_pages_node_noprof include/linux/gfp.h:296 [inline]
>  alloc_slab_page+0x5f/0x120 mm/slub.c:2319
>  allocate_slab+0x5a/0x2f0 mm/slub.c:2482
>  new_slab mm/slub.c:2535 [inline]
>  ___slab_alloc+0xcd1/0x14b0 mm/slub.c:3721
>  __slab_alloc+0x58/0xa0 mm/slub.c:3811
>  __slab_alloc_node mm/slub.c:3864 [inline]
>  slab_alloc_node mm/slub.c:4026 [inline]
>  __do_kmalloc_node mm/slub.c:4158 [inline]
>  __kmalloc_noprof+0x25a/0x400 mm/slub.c:4171
>  kmalloc_noprof include/linux/slab.h:694 [inline]
>  load_elf_phdrs+0x162/0x260 fs/binfmt_elf.c:526
>  load_elf_binary+0x920/0x2680 fs/binfmt_elf.c:955
>  search_binary_handler fs/exec.c:1820 [inline]
>  exec_binprm fs/exec.c:1862 [inline]
>  bprm_execve+0xaf8/0x1770 fs/exec.c:1913
>  do_execveat_common+0x55f/0x6f0 fs/exec.c:2020
>  do_execve fs/exec.c:2094 [inline]
>  __do_sys_execve fs/exec.c:2170 [inline]
>  __se_sys_execve fs/exec.c:2165 [inline]
>  __x64_sys_execve+0x92/0xb0 fs/exec.c:2165
>  do_syscall_x64 arch/x86/entry/common.c:52 [inline]
>  do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
>  entry_SYSCALL_64_after_hwframe+0x77/0x7f
> page last free pid 5032 tgid 5032 stack trace:
>  reset_page_owner include/linux/page_owner.h:25 [inline]
>  free_pages_prepare mm/page_alloc.c:1101 [inline]
>  free_unref_page+0xd22/0xea0 mm/page_alloc.c:2619
>  __slab_free+0x31b/0x3d0 mm/slub.c:4385
>  qlink_free mm/kasan/quarantine.c:163 [inline]
>  qlist_free_all+0x9e/0x140 mm/kasan/quarantine.c:179
>  kasan_quarantine_reduce+0x14f/0x170 mm/kasan/quarantine.c:286
>  __kasan_slab_alloc+0x23/0x80 mm/kasan/common.c:322
>  kasan_slab_alloc include/linux/kasan.h:201 [inline]
>  slab_post_alloc_hook mm/slub.c:3989 [inline]
>  slab_alloc_node mm/slub.c:4038 [inline]
>  __do_kmalloc_node mm/slub.c:4158 [inline]
>  __kmalloc_noprof+0x1a6/0x400 mm/slub.c:4171
>  kmalloc_noprof include/linux/slab.h:694 [inline]
>  tomoyo_realpath_from_path+0xcf/0x5e0 security/tomoyo/realpath.c:251
>  tomoyo_get_realpath security/tomoyo/file.c:151 [inline]
>  tomoyo_path_perm+0x2b7/0x740 security/tomoyo/file.c:822
>  security_inode_getattr+0x130/0x330 security/security.c:2371
>  vfs_getattr+0x45/0x430 fs/stat.c:204
>  vfs_fstat fs/stat.c:229 [inline]
>  vfs_fstatat+0xe4/0x190 fs/stat.c:338
>  __do_sys_newfstatat fs/stat.c:505 [inline]
>  __se_sys_newfstatat fs/stat.c:499 [inline]
>  __x64_sys_newfstatat+0x11d/0x1a0 fs/stat.c:499
>  do_syscall_x64 arch/x86/entry/common.c:52 [inline]
>  do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
>  entry_SYSCALL_64_after_hwframe+0x77/0x7f
> 
> Memory state around the buggy address:
>  ffff888036426700: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>  ffff888036426780: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
> >ffff888036426800: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>                                                  ^
>  ffff888036426880: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>  ffff888036426900: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
> ==================================================================
> 
> 
> ---
> This report is generated by a bot. It may contain errors.
> See https://goo.gl/tpsmEJ for more information about syzbot.
> syzbot engineers can be reached at syzkaller@googlegroups.com.
> 
> syzbot will keep track of this issue. See:
> https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
> 
> If the report is already addressed, let syzbot know by replying with:
> #syz fix: exact-commit-title
> 
> If you want syzbot to run the reproducer, reply with:
> #syz test: git://repo/address.git branch-or-commit-hash
> If you attach or paste a git patch, syzbot will apply it before testing.
> 
> If you want to overwrite report's subsystems, reply with:
> #syz set subsystems: new-subsystem
> (See the list of subsystem names on the web dashboard)
> 
> If the report is a duplicate of another one, reply with:
> #syz dup: exact-subject-of-another-report
> 
> If you want to undo deduplication, reply with:
> #syz undup
> 

#syz test

diff --git a/fs/ext4/xattr.c b/fs/ext4/xattr.c
index 46ce2f21fef9..336badb46246 100644
--- a/fs/ext4/xattr.c
+++ b/fs/ext4/xattr.c
@@ -1776,7 +1776,14 @@ static int ext4_xattr_set_entry(struct ext4_xattr_info *i,
 	} else if (s->not_found) {
 		/* Insert new name. */
 		size_t size = EXT4_XATTR_LEN(name_len);
-		size_t rest = (void *)last - (void *)here + sizeof(__u32);
+		size_t rest;
+
+		if (last < here) {
+			ret = -ENOSPC;
+			goto out;
+		} else {
+			rest = (void *)last - (void *)here + sizeof(__u32);
+		}
 
 		memmove((void *)here + size, here, rest);
 		memset(here, 0, size);
-- 
Best,
Qianqiang Liu

Re: [syzbot] [ext4?] KASAN: out-of-bounds Read in ext4_xattr_set_entry

[syzbot]

Hello,

syzbot has tested the proposed patch and the reproducer did not trigger any issue:

Reported-by: syzbot+f792df426ff0f5ceb8d1@syzkaller.appspotmail.com
Tested-by: syzbot+f792df426ff0f5ceb8d1@syzkaller.appspotmail.com

Tested on:

commit:         88264981 Merge tag 'sched_ext-for-6.12' of git://git.k..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=17c78e07980000
kernel config:  https://syzkaller.appspot.com/x/.config?x=5b5c53071a819d59
dashboard link: https://syzkaller.appspot.com/bug?extid=f792df426ff0f5ceb8d1
compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
patch:          https://syzkaller.appspot.com/x/patch.diff?x=16538e07980000

Note: testing is done by a robot and is best-effort only.

Re: [syzbot] [ext4?] KASAN: out-of-bounds Read in ext4_xattr_set_entry

[Qianqiang Liu]

#syz test

diff --git a/fs/ext4/xattr.c b/fs/ext4/xattr.c
index e0e1956dcdd3..649b278d4c1f 100644
--- a/fs/ext4/xattr.c
+++ b/fs/ext4/xattr.c
@@ -1884,7 +1884,7 @@ ext4_xattr_block_find(struct inode *inode, struct ext4_xattr_info *i,
 		bs->s.here = bs->s.first;
 		error = xattr_find_entry(inode, &bs->s.here, bs->s.end,
 					 i->name_index, i->name, 1);
-		if (error && error != -ENODATA)
+		if (error)
 			return error;
 		bs->s.not_found = error;
 	}

-- 
Best,
Qianqiang Liu

Re: [syzbot] [ext4?] KASAN: out-of-bounds Read in ext4_xattr_set_entry

[syzbot]

Hello,

syzbot has tested the proposed patch and the reproducer did not trigger any issue:

Reported-by: syzbot+f792df426ff0f5ceb8d1@syzkaller.appspotmail.com
Tested-by: syzbot+f792df426ff0f5ceb8d1@syzkaller.appspotmail.com

Tested on:

commit:         e32cde8d Merge tag 'sched_ext-for-6.12-rc1-fixes-1' of..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=13657dd0580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=286b31f2cf1c36b5
dashboard link: https://syzkaller.appspot.com/bug?extid=f792df426ff0f5ceb8d1
compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
patch:          https://syzkaller.appspot.com/x/patch.diff?x=122da580580000

Note: testing is done by a robot and is best-effort only.

Re: [syzbot] [ext4?] KASAN: out-of-bounds Read in ext4_xattr_set_entry

[syzbot]

Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
KASAN: out-of-bounds Read in ext4_xattr_set_entry

EXT4-fs (loop0): 1 truncate cleaned up
EXT4-fs (loop0): mounted filesystem 00000000-0000-0000-0000-000000000000 r/w without journal. Quota mode: writeback.
==================================================================
BUG: KASAN: out-of-bounds in ext4_xattr_set_entry+0x8e9/0x1e20 fs/ext4/xattr.c:1782
Read of size 18446744073709551572 at addr ffff88800077a050 by task syz.0.17/5873

CPU: 0 UID: 0 PID: 5873 Comm: syz.0.17 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
Call Trace:
 <TASK>
 dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:378 [inline]
 print_report+0xca/0x240 mm/kasan/report.c:482
 kasan_report+0x118/0x150 mm/kasan/report.c:595
 check_region_inline mm/kasan/generic.c:-1 [inline]
 kasan_check_range+0x2b0/0x2c0 mm/kasan/generic.c:200
 __asan_memmove+0x29/0x70 mm/kasan/shadow.c:94
 ext4_xattr_set_entry+0x8e9/0x1e20 fs/ext4/xattr.c:1782
 ext4_xattr_block_set+0x872/0x2ac0 fs/ext4/xattr.c:2029
 ext4_xattr_move_to_block fs/ext4/xattr.c:2668 [inline]
 ext4_xattr_make_inode_space fs/ext4/xattr.c:2743 [inline]
 ext4_expand_extra_isize_ea+0x12da/0x1ea0 fs/ext4/xattr.c:2831
 __ext4_expand_extra_isize+0x30d/0x400 fs/ext4/inode.c:6349
 ext4_try_to_expand_extra_isize fs/ext4/inode.c:6392 [inline]
 __ext4_mark_inode_dirty+0x45c/0x6e0 fs/ext4/inode.c:6470
 __ext4_unlink+0x631/0xab0 fs/ext4/namei.c:3282
 ext4_unlink+0x206/0x590 fs/ext4/namei.c:3312
 vfs_unlink+0x380/0x640 fs/namei.c:5369
 do_unlinkat+0x2cf/0x560 fs/namei.c:5439
 __do_sys_unlink fs/namei.c:5474 [inline]
 __se_sys_unlink fs/namei.c:5472 [inline]
 __x64_sys_unlink+0x47/0x50 fs/namei.c:5472
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7ff419d8f7c9
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ff41abdb038 EFLAGS: 00000246 ORIG_RAX: 0000000000000057
RAX: ffffffffffffffda RBX: 00007ff419fe5fa0 RCX: 00007ff419d8f7c9
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000200000000180
RBP: 00007ff419e13f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ff419fe6038 R14: 00007ff419fe5fa0 R15: 00007fff883d93a8
 </TASK>

Allocated by task 5873:
 kasan_save_stack mm/kasan/common.c:56 [inline]
 kasan_save_track+0x3e/0x80 mm/kasan/common.c:77
 poison_kmalloc_redzone mm/kasan/common.c:397 [inline]
 __kasan_kmalloc+0x93/0xb0 mm/kasan/common.c:414
 kasan_kmalloc include/linux/kasan.h:262 [inline]
 __do_kmalloc_node mm/slub.c:5657 [inline]
 __kmalloc_node_track_caller_noprof+0x575/0x820 mm/slub.c:5764
 kmemdup_noprof+0x2b/0x70 mm/util.c:138
 kmemdup_noprof include/linux/fortify-string.h:765 [inline]
 ext4_xattr_block_set+0x781/0x2ac0 fs/ext4/xattr.c:1977
 ext4_xattr_move_to_block fs/ext4/xattr.c:2668 [inline]
 ext4_xattr_make_inode_space fs/ext4/xattr.c:2743 [inline]
 ext4_expand_extra_isize_ea+0x12da/0x1ea0 fs/ext4/xattr.c:2831
 __ext4_expand_extra_isize+0x30d/0x400 fs/ext4/inode.c:6349
 ext4_try_to_expand_extra_isize fs/ext4/inode.c:6392 [inline]
 __ext4_mark_inode_dirty+0x45c/0x6e0 fs/ext4/inode.c:6470
 __ext4_unlink+0x631/0xab0 fs/ext4/namei.c:3282
 ext4_unlink+0x206/0x590 fs/ext4/namei.c:3312
 vfs_unlink+0x380/0x640 fs/namei.c:5369
 do_unlinkat+0x2cf/0x560 fs/namei.c:5439
 __do_sys_unlink fs/namei.c:5474 [inline]
 __se_sys_unlink fs/namei.c:5472 [inline]
 __x64_sys_unlink+0x47/0x50 fs/namei.c:5472
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

The buggy address belongs to the object at ffff88800077a000
 which belongs to the cache kmalloc-1k of size 1024
The buggy address is located 80 bytes inside of
 1024-byte region [ffff88800077a000, ffff88800077a400)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x778
head: order:2 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
flags: 0x7ff00000000040(head|node=0|zone=0|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 007ff00000000040 ffff88801a441dc0 dead000000000122 0000000000000000
raw: 0000000000000000 0000000080080008 00000000f5000000 0000000000000000
head: 007ff00000000040 ffff88801a441dc0 dead000000000122 0000000000000000
head: 0000000000000000 0000000080080008 00000000f5000000 0000000000000000
head: 007ff00000000002 ffffea000001de01 00000000ffffffff 00000000ffffffff
head: ffffffffffffffff 0000000000000000 00000000ffffffff 0000000000000004
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 2, migratetype Unmovable, gfp_mask 0x252800(GFP_NOWAIT|__GFP_NORETRY|__GFP_COMP|__GFP_THISNODE), pid 5873, tgid 5872 (syz.0.17), ts 160723892073, free_ts 160040949869
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x234/0x290 mm/page_alloc.c:1846
 prep_new_page mm/page_alloc.c:1854 [inline]
 get_page_from_freelist+0x2365/0x2440 mm/page_alloc.c:3915
 __alloc_pages_slowpath+0x30b/0xce0 mm/page_alloc.c:4741
 __alloc_frozen_pages_noprof+0x319/0x370 mm/page_alloc.c:5223
 alloc_slab_page mm/slub.c:3077 [inline]
 allocate_slab+0x7a/0x3b0 mm/slub.c:3248
 new_slab mm/slub.c:3302 [inline]
 ___slab_alloc+0xf2b/0x1960 mm/slub.c:4656
 __slab_alloc+0x65/0x100 mm/slub.c:4779
 __slab_alloc_node mm/slub.c:4855 [inline]
 slab_alloc_node mm/slub.c:5251 [inline]
 __do_kmalloc_node mm/slub.c:5656 [inline]
 __kmalloc_node_noprof+0x5d9/0x820 mm/slub.c:5663
 kmalloc_array_node_noprof include/linux/slab.h:1075 [inline]
 alloc_slab_obj_exts+0x3e/0x100 mm/slub.c:2123
 __memcg_slab_post_alloc_hook+0x330/0x730 mm/memcontrol.c:3197
 memcg_slab_post_alloc_hook mm/slub.c:2338 [inline]
 slab_post_alloc_hook mm/slub.c:4964 [inline]
 slab_alloc_node mm/slub.c:5263 [inline]
 __do_kmalloc_node mm/slub.c:5656 [inline]
 __kmalloc_node_track_caller_noprof+0x5f3/0x820 mm/slub.c:5764
 __kmemdup_nul mm/util.c:64 [inline]
 kstrdup+0x42/0x100 mm/util.c:84
 alloc_vfsmnt+0xeb/0x430 fs/namespace.c:302
 vfs_create_mount+0x69/0x320 fs/namespace.c:1184
 fc_mount fs/namespace.c:1202 [inline]
 do_new_mount_fc fs/namespace.c:3636 [inline]
 do_new_mount+0x390/0xa10 fs/namespace.c:3712
 do_mount fs/namespace.c:4035 [inline]
 __do_sys_mount fs/namespace.c:4224 [inline]
 __se_sys_mount+0x313/0x410 fs/namespace.c:4201
page last free pid 5862 tgid 5862 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 free_pages_prepare mm/page_alloc.c:1395 [inline]
 __free_frozen_pages+0xbc8/0xd30 mm/page_alloc.c:2943
 __slab_free+0x21b/0x2a0 mm/slub.c:6004
 qlink_free mm/kasan/quarantine.c:163 [inline]
 qlist_free_all+0x97/0x100 mm/kasan/quarantine.c:179
 kasan_quarantine_reduce+0x148/0x160 mm/kasan/quarantine.c:286
 __kasan_slab_alloc+0x22/0x80 mm/kasan/common.c:349
 kasan_slab_alloc include/linux/kasan.h:252 [inline]
 slab_post_alloc_hook mm/slub.c:4953 [inline]
 slab_alloc_node mm/slub.c:5263 [inline]
 kmem_cache_alloc_noprof+0x37d/0x710 mm/slub.c:5270
 getname_flags+0xb8/0x540 fs/namei.c:146
 getname include/linux/fs.h:2498 [inline]
 do_sys_openat2+0xbc/0x200 fs/open.c:1426
 do_sys_open fs/open.c:1436 [inline]
 __do_sys_openat fs/open.c:1452 [inline]
 __se_sys_openat fs/open.c:1447 [inline]
 __x64_sys_openat+0x138/0x170 fs/open.c:1447
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Memory state around the buggy address:
 ffff888000779f00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff888000779f80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff88800077a000: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
                                                 ^
 ffff88800077a080: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff88800077a100: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
==================================================================


Tested on:

commit:         40fbbd64 Merge tag 'pull-fixes' of git://git.kernel.or..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=16918392580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=72e765d013fc99c
dashboard link: https://syzkaller.appspot.com/bug?extid=f792df426ff0f5ceb8d1
compiler:       Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8

Note: no patches were applied.

[PATCH] ext4: xattr: fix wrong search.here in clone_block

[Jinchao Wang]

syzbot reported a KASAN out-of-bounds Read in ext4_xattr_set_entry()[1].

When xattr_find_entry() returns -ENODATA, search.here still points to the
position after the last valid entry. ext4_xattr_block_set() clones the xattr
block because the original block maybe shared and must not be modified in
place.

In the clone_block, search.here is recomputed unconditionally from the old
offset, which may place it past search.first. This results in a negative
reset size and an out-of-bounds memmove() in ext4_xattr_set_entry().

Fix this by initializing search.here correctly when search.not_found is set.

#syz test

[1] https://syzkaller.appspot.com/bug?extid=f792df426ff0f5ceb8d1

Fixes: fd48e9acdf2 (ext4: Unindent codeblock in ext4_xattr_block_set)
Cc: stable@vger.kernel.org
Reported-by: syzbot+f792df426ff0f5ceb8d1@syzkaller.appspotmail.com
Signed-off-by: Jinchao Wang <wangjinchao600@gmail.com>
---
 fs/ext4/xattr.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/fs/ext4/xattr.c b/fs/ext4/xattr.c
index 2e02efbddaac..cc30abeb7f30 100644
--- a/fs/ext4/xattr.c
+++ b/fs/ext4/xattr.c
@@ -1980,7 +1980,10 @@ ext4_xattr_block_set(handle_t *handle, struct inode *inode,
 			goto cleanup;
 		s->first = ENTRY(header(s->base)+1);
 		header(s->base)->h_refcount = cpu_to_le32(1);
-		s->here = ENTRY(s->base + offset);
+		if (s->not_found)
+			s->here = s->first;
+		else
+			s->here = ENTRY(s->base + offset);
 		s->end = s->base + bs->bh->b_size;
 
 		/*
-- 
2.43.0

Re: [syzbot] [ext4?] KASAN: out-of-bounds Read in ext4_xattr_set_entry

[syzbot]

Hello,

syzbot has tested the proposed patch and the reproducer did not trigger any issue:

Reported-by: syzbot+f792df426ff0f5ceb8d1@syzkaller.appspotmail.com
Tested-by: syzbot+f792df426ff0f5ceb8d1@syzkaller.appspotmail.com

Tested on:

commit:         40fbbd64 Merge tag 'pull-fixes' of git://git.kernel.or..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=154c931a580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=72e765d013fc99c
dashboard link: https://syzkaller.appspot.com/bug?extid=f792df426ff0f5ceb8d1
compiler:       Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8
patch:          https://syzkaller.appspot.com/x/patch.diff?x=118de184580000

Note: testing is done by a robot and is best-effort only.