KASAN: vmalloc-out-of-bounds Read in xfs_buf_lock

Status: upstream: reported on 2026/03/25 04:24
Reported-by: syzbot+de5ae0fe914bc0ecf264@syzkaller.appspotmail.com
First crash: 146d, last: 84d
▶ ▼ Similar bugs (5)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-6.1 KASAN: vmalloc-out-of-bounds Read in xfs_buf_lock origin:lts-only 17 syz, C inconclusive 3 84d 198d 0/3 upstream: reported C repro on 2026/02/01 05:42
linux-6.1 KASAN: stack-out-of-bounds Read in xfs_buf_lock (2) 17 1 1019d 1019d 0/3 auto-obsoleted due to no activity on 2024/02/11 11:29
linux-6.6 KASAN: stack-out-of-bounds Read in xfs_buf_lock 17 1 305d 305d 0/2 auto-obsoleted due to no activity on 2026/01/25 03:43
upstream KASAN: stack-out-of-bounds Read in xfs_buf_lock xfs 17 syz, C error unreliable 866 574d 1345d 0/29 auto-obsoleted due to no activity on 2025/04/01 11:07
linux-6.1 KASAN: stack-out-of-bounds Read in xfs_buf_lock 17 1 1147d 1147d 0/3 auto-obsoleted due to no activity on 2023/10/06 04:59

Sample crash report:
==================================================================
BUG: KASAN: vmalloc-out-of-bounds in xfs_buf_lock+0x22c/0x460 fs/xfs/xfs_buf.c:1124
Read of size 4 at addr ffffc900034278fc by task syz.9.3267/19593

CPU: 0 PID: 19593 Comm: syz.9.3267 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0x18c/0x250 lib/dump_stack.c:106
 print_address_description mm/kasan/report.c:364 [inline]
 print_report+0xa8/0x210 mm/kasan/report.c:468
 kasan_report+0x117/0x150 mm/kasan/report.c:581
 xfs_buf_lock+0x22c/0x460 fs/xfs/xfs_buf.c:1124
 xfs_buf_delwri_submit_buffers+0x15f/0x890 fs/xfs/xfs_buf.c:2211
 xfs_buf_delwri_submit+0xc5/0x250 fs/xfs/xfs_buf.c:2289
 xfs_qm_shrink_scan+0x1a7/0x3a0 fs/xfs/xfs_qm.c:522
 do_shrink_slab+0x50f/0xd10 mm/vmscan.c:907
 shrink_slab+0x1d0/0x7f0 mm/vmscan.c:1067
 drop_slab_node mm/vmscan.c:1095 [inline]
 drop_slab+0x15b/0x2a0 mm/vmscan.c:1113
 drop_caches_sysctl_handler+0xc7/0x170 fs/drop_caches.c:68
 proc_sys_call_handler+0x463/0x6d0 fs/proc/proc_sysctl.c:599
 do_iter_readv_writev fs/read_write.c:-1 [inline]
 do_iter_write+0x738/0xc30 fs/read_write.c:860
 vfs_writev fs/read_write.c:933 [inline]
 do_writev+0x27f/0x480 fs/read_write.c:976
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7fa29099ce59
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:00007fa2917d5028 EFLAGS: 00000246 ORIG_RAX: 0000000000000014
RAX: ffffffffffffffda RBX: 00007fa290c15fa0 RCX: 00007fa29099ce59
RDX: 0000000000000001 RSI: 00002000000000c0 RDI: 000000000000000c
RBP: 00007fa290a32d6f R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fa290c16038 R14: 00007fa290c15fa0 R15: 00007ffc62ea0598
 </TASK>

The buggy address belongs to a 8-page vmalloc region starting at 0xffffc90003420000 allocated at copy_process+0x586/0x3dc0 kernel/fork.c:2333
The buggy address belongs to the physical page:
page:ffffea00007bb8c0 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x1eee3
memcg:ffff88805991cd02
flags: 0xfff00000000000(node=0|zone=1|lastcpupid=0x7ff)
page_type: 0xffffffff()
raw: 00fff00000000000 0000000000000000 dead000000000122 0000000000000000
raw: 0000000000000000 0000000000000000 00000001ffffffff ffff88805991cd02
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 0, migratetype Unmovable, gfp_mask 0x102dc2(GFP_HIGHUSER|__GFP_NOWARN|__GFP_ZERO), pid 19579, tgid 19579 (syz.7.3259), ts 1556738230580, free_ts 1553886004424
 set_page_owner include/linux/page_owner.h:31 [inline]
 post_alloc_hook+0x1c1/0x200 mm/page_alloc.c:1581
 prep_new_page mm/page_alloc.c:1588 [inline]
 get_page_from_freelist+0x1951/0x19e0 mm/page_alloc.c:3220
 __alloc_pages+0x1f0/0x460 mm/page_alloc.c:4500
 vm_area_alloc_pages mm/vmalloc.c:3089 [inline]
 __vmalloc_area_node mm/vmalloc.c:3158 [inline]
 __vmalloc_node_range+0x956/0x1330 mm/vmalloc.c:3339
 alloc_thread_stack_node kernel/fork.c:311 [inline]
 dup_task_struct+0x3d0/0x7c0 kernel/fork.c:1126
 copy_process+0x586/0x3dc0 kernel/fork.c:2333
 kernel_clone+0x24b/0x8a0 kernel/fork.c:2917
 __do_sys_clone3 kernel/fork.c:3218 [inline]
 __se_sys_clone3+0x334/0x350 kernel/fork.c:3202
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
page last free stack trace:
 reset_page_owner include/linux/page_owner.h:24 [inline]
 free_pages_prepare mm/page_alloc.c:1181 [inline]
 free_unref_page_prepare+0x7b2/0x8c0 mm/page_alloc.c:2365
 free_unref_page+0x32/0x2e0 mm/page_alloc.c:2458
 vfree+0x1a6/0x320 mm/vmalloc.c:2868
 htab_map_alloc+0x8b1/0xe80 kernel/bpf/hashtab.c:608
 map_create+0x877/0x12f0 kernel/bpf/syscall.c:1247
 __sys_bpf+0x651/0x890 kernel/bpf/syscall.c:5459
 __do_sys_bpf kernel/bpf/syscall.c:5581 [inline]
 __se_sys_bpf kernel/bpf/syscall.c:5579 [inline]
 __x64_sys_bpf+0x7c/0x90 kernel/bpf/syscall.c:5579
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2

Memory state around the buggy address:
 ffffc90003427780: 00 00 00 00 00 00 00 00 00 00 00 00 f1 f1 f1 f1
 ffffc90003427800: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
>ffffc90003427880: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
                                                                ^
 ffffc90003427900: f3 f3 f3 f3 f3 f3 f3 f3 00 00 00 00 00 00 00 00
 ffffc90003427980: 00 00 00 00 00 00 00 00 00 00 00 00 f1 f1 f1 f1
==================================================================

Crashes (2):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/05/26 03:49 linux-6.6.y 0a40c6fbd105 c69befb3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: vmalloc-out-of-bounds Read in xfs_buf_lock
2026/03/25 04:24 linux-6.6.y 4fc00fe35d46 74e70d19 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: vmalloc-out-of-bounds Read in xfs_buf_lock
* Struck through repros no longer work on HEAD.