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

Status: premoderation: reported C repro on 2026/10/11 05:13
Reported-by: syzbot+f8300b04b366694f5d85@syzkaller.appspotmail.com
First crash: 2d20h, last: 2d20h
▶ ▼ Similar bugs (1)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
android-6-1 KASAN: use-after-free Read in link_path_walk origin:lts 19 syz, C error 1 83d 83d 0/2 upstream: reported C repro on 2026/07/22 21:01

Sample crash report:
==================================================================
BUG: KASAN: slab-out-of-bounds in link_path_walk+0x9e9/0xeb0 fs/namei.c:2403
Read of size 1 at addr ffff88810ee58589 by task syz.1.4164/12287

CPU: 0 UID: 0 PID: 12287 Comm: syz.1.4164 Not tainted syzkaller #0 ca35313610c8ed713bced2230d6c22219bd85c1d
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/16/2026
Call Trace:
 <TASK>
 __dump_stack+0x21/0x30 lib/dump_stack.c:94
 dump_stack_lvl+0x140/0x1c0 lib/dump_stack.c:120
 print_address_description+0x71/0x210 mm/kasan/report.c:377
 print_report+0x4a/0x70 mm/kasan/report.c:481
 kasan_report+0x162/0x1a0 mm/kasan/report.c:594
 __asan_report_load1_noabort+0x18/0x20 mm/kasan/report_generic.c:378
 link_path_walk+0x9e9/0xeb0 fs/namei.c:2403
 path_parentat fs/namei.c:2635 [inline]
 __filename_parentat+0x231/0x660 fs/namei.c:2659
 filename_parentat fs/namei.c:2677 [inline]
 do_unlinkat+0xfe/0x5a0 fs/namei.c:4516
 __do_sys_unlinkat fs/namei.c:4584 [inline]
 __se_sys_unlinkat fs/namei.c:4577 [inline]
 __x64_sys_unlinkat+0xda/0xf0 fs/namei.c:4577
 x64_sys_call+0x2974/0x2ee0 arch/x86/include/generated/asm/syscalls_64.h:264
 do_syscall_x64 arch/x86/entry/common.c:47 [inline]
 do_syscall_64+0x57/0xf0 arch/x86/entry/common.c:78
 entry_SYSCALL_64_after_hwframe+0x76/0x7e
RIP: 0033:0x7ff60e99e1d9
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:00007ff60f903028 EFLAGS: 00000246 ORIG_RAX: 0000000000000107
RAX: ffffffffffffffda RBX: 00007ff60ec26090 RCX: 00007ff60e99e1d9
RDX: 0000000000000000 RSI: 00002000000003c0 RDI: 0000000000000004
RBP: 00007ff60ea35888 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ff60ec26128 R14: 00007ff60ec26090 R15: 00007ffeb26b74e8
 </TASK>

Allocated by task 12283:
 kasan_save_stack mm/kasan/common.c:49 [inline]
 kasan_save_track+0x3e/0x80 mm/kasan/common.c:70
 kasan_save_alloc_info+0x3a/0x50 mm/kasan/generic.c:565
 poison_kmalloc_redzone mm/kasan/common.c:379 [inline]
 __kasan_kmalloc+0x96/0xb0 mm/kasan/common.c:396
 kasan_kmalloc include/linux/kasan.h:261 [inline]
 __do_kmalloc_node mm/slub.c:4395 [inline]
 __kmalloc_node_track_caller_noprof+0x24e/0x4f0 mm/slub.c:4414
 kstrdup+0x4d/0x130 mm/util.c:70
 bpf_symlink+0x2d/0x200 kernel/bpf/inode.c:386
 vfs_symlink+0x3f7/0x620 fs/namei.c:4623
 do_symlinkat+0x1ba/0x400 fs/namei.c:4649
 __do_sys_symlinkat fs/namei.c:4665 [inline]
 __se_sys_symlinkat fs/namei.c:4662 [inline]
 __x64_sys_symlinkat+0x99/0xb0 fs/namei.c:4662
 x64_sys_call+0x1f79/0x2ee0 arch/x86/include/generated/asm/syscalls_64.h:267
 do_syscall_x64 arch/x86/entry/common.c:47 [inline]
 do_syscall_64+0x57/0xf0 arch/x86/entry/common.c:78
 entry_SYSCALL_64_after_hwframe+0x76/0x7e

Freed by task 12283:
 kasan_save_stack mm/kasan/common.c:49 [inline]
 kasan_save_track+0x3e/0x80 mm/kasan/common.c:70
 kasan_save_free_info+0x44/0x50 mm/kasan/generic.c:579
 poison_slab_object mm/kasan/common.c:249 [inline]
 __kasan_slab_free+0x5f/0x80 mm/kasan/common.c:266
 kasan_slab_free include/linux/kasan.h:234 [inline]
 slab_free_hook mm/slub.c:2445 [inline]
 slab_free mm/slub.c:4714 [inline]
 kfree+0x158/0x440 mm/slub.c:4875
 bpf_destroy_inode+0x7e/0x180 kernel/bpf/inode.c:783
 destroy_inode fs/inode.c:319 [inline]
 evict+0x820/0xaf0 fs/inode.c:762
 iput_final fs/inode.c:1890 [inline]
 iput+0x651/0x910 fs/inode.c:1916
 do_unlinkat+0x3d2/0x5a0 fs/namei.c:4548
 __do_sys_unlinkat fs/namei.c:4584 [inline]
 __se_sys_unlinkat fs/namei.c:4577 [inline]
 __x64_sys_unlinkat+0xda/0xf0 fs/namei.c:4577
 x64_sys_call+0x2974/0x2ee0 arch/x86/include/generated/asm/syscalls_64.h:264
 do_syscall_x64 arch/x86/entry/common.c:47 [inline]
 do_syscall_64+0x57/0xf0 arch/x86/entry/common.c:78
 entry_SYSCALL_64_after_hwframe+0x76/0x7e

The buggy address belongs to the object at ffff88810ee58580
 which belongs to the cache kmalloc-8 of size 8
The buggy address is located 1 bytes to the right of
 allocated 8-byte region [ffff88810ee58580, ffff88810ee58588)

The buggy address belongs to the physical page:
page: refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x10ee58
flags: 0x4000000000000000(zone=1)
page_type: f5(slab)
raw: 4000000000000000 ffff888100041500 dead000000000100 dead000000000122
raw: 0000000000000000 0000000080800080 00000001f5000000 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 0x52cc0(GFP_KERNEL|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP), pid 1, tgid 1 (swapper/0), ts 2459829404, free_ts 0
 set_page_owner include/linux/page_owner.h:35 [inline]
 post_alloc_hook+0x37d/0x3b0 mm/page_alloc.c:1864
 prep_new_page+0x2d/0x180 mm/page_alloc.c:1872
 get_page_from_freelist+0x4aea/0x4ba0 mm/page_alloc.c:3949
 __alloc_pages_noprof+0x35a/0x7e0 mm/page_alloc.c:5316
 alloc_slab_page+0x6b/0x1e0 mm/slub.c:-1
 allocate_slab+0x69/0x430 mm/slub.c:2687
 new_slab mm/slub.c:2741 [inline]
 ___slab_alloc+0x591/0x8c0 mm/slub.c:3934
 __slab_alloc mm/slub.c:4025 [inline]
 __slab_alloc_node mm/slub.c:4078 [inline]
 slab_alloc_node mm/slub.c:4239 [inline]
 __do_kmalloc_node mm/slub.c:4394 [inline]
 __kmalloc_noprof+0x2fc/0x510 mm/slub.c:4407
 kmalloc_noprof include/linux/slab.h:886 [inline]
 kzalloc_noprof include/linux/slab.h:1117 [inline]
 acpi_ns_internalize_name+0x2df/0x490 drivers/acpi/acpica/nsutils.c:331
 acpi_ns_get_node_unlocked drivers/acpi/acpica/nsutils.c:666 [inline]
 acpi_ns_get_node+0x1ab/0x360 drivers/acpi/acpica/nsutils.c:726
 acpi_get_handle+0x188/0x290 drivers/acpi/acpica/nsxfname.c:98
 acpi_has_method+0x8d/0xe0 drivers/acpi/utils.c:673
 acpi_ata_match drivers/acpi/scan.c:1225 [inline]
 acpi_bay_match+0x12a/0x1e0 drivers/acpi/scan.c:1240
 acpi_set_pnp_ids drivers/acpi/scan.c:1450 [inline]
 acpi_init_device_object+0x124f/0x1690 drivers/acpi/scan.c:1833
 acpi_add_single_object+0x10a/0x1a10 drivers/acpi/scan.c:1884
 acpi_bus_check_add+0x373/0x860 drivers/acpi/scan.c:2185
page_owner free stack trace missing

Memory state around the buggy address:
 ffff88810ee58480: fa fc fc fc fa fc fc fc fa fc fc fc fa fc fc fc
 ffff88810ee58500: fa fc fc fc fa fc fc fc fa fc fc fc fa fc fc fc
>ffff88810ee58580: fa fc fc fc fa fc fc fc fa fc fc fc fa fc fc fc
                      ^
 ffff88810ee58600: fa fc fc fc fa fc fc fc fa fc fc fc fa fc fc fc
 ffff88810ee58680: fa fc fc fc fa fc fc fc fa fc fc fc fa fc fc fc
==================================================================

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/10/11 05:12 android16-6.12 e65d894191a4 4f92358f .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-android-6-12-rust KASAN: slab-out-of-bounds Read in link_path_walk
* Struck through repros no longer work on HEAD.