[moderation] [fs?] KASAN: stack-out-of-bounds Read in unwind_next_frame (4)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: f7301f856d35 Merge tag 'io_uring-6.16-20250621' of git://g..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=159c0ebc580000
kernel config: https://syzkaller.appspot.com/x/.config?x=5f3f62311f35cdd9
dashboard link: https://syzkaller.appspot.com/bug?extid=cf96b6699756e1fe8503
compiler: gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40
CC: [linux-...@vger.kernel.org linux-...@vger.kernel.org]

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/e541ddc233a7/disk-f7301f85.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/7cd632067593/vmlinux-f7301f85.xz
kernel image: https://storage.googleapis.com/syzbot-assets/53a59b4d4029/bzImage-f7301f85.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+cf96b6...@syzkaller.appspotmail.com

==================================================================
BUG: KASAN: stack-out-of-bounds in user_mode arch/x86/include/asm/ptrace.h:214 [inline]
BUG: KASAN: stack-out-of-bounds in unwind_next_frame+0xb47/0x20a0 arch/x86/kernel/unwind_orc.c:482
Read of size 2 at addr ffffc90003c4fde0 by task syz.0.710/10960

CPU: 1 UID: 0 PID: 10960 Comm: syz.0.710 Not tainted 6.16.0-rc2-syzkaller-00308-gf7301f856d35 #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:94 [inline]
dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120
print_address_description mm/kasan/report.c:408 [inline]
print_report+0xcd/0x680 mm/kasan/report.c:521
kasan_report+0xe0/0x110 mm/kasan/report.c:634
user_mode arch/x86/include/asm/ptrace.h:214 [inline]
unwind_next_frame+0xb47/0x20a0 arch/x86/kernel/unwind_orc.c:482
arch_stack_walk+0x94/0x100 arch/x86/kernel/stacktrace.c:25
stack_trace_save_tsk+0x165/0x1f0 kernel/stacktrace.c:150
proc_pid_stack+0x16e/0x2b0 fs/proc/base.c:492
proc_single_show+0x124/0x220 fs/proc/base.c:812
traverse.part.0.constprop.0+0x107/0x640 fs/seq_file.c:111
traverse fs/seq_file.c:98 [inline]
seq_read_iter+0x932/0x12c0 fs/seq_file.c:195
seq_read+0x39e/0x4e0 fs/seq_file.c:162
vfs_read+0x1e4/0xc60 fs/read_write.c:570
ksys_pread64 fs/read_write.c:763 [inline]
__do_sys_pread64 fs/read_write.c:771 [inline]
__se_sys_pread64 fs/read_write.c:768 [inline]
__x64_sys_pread64+0x1eb/0x250 fs/read_write.c:768
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xcd/0x4c0 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f1d2b78e929
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:00007f1d295b4038 EFLAGS: 00000246 ORIG_RAX: 0000000000000011
RAX: ffffffffffffffda RBX: 00007f1d2b9b6160 RCX: 00007f1d2b78e929
RDX: 00000000000000ed RSI: 0000200000002240 RDI: 0000000000000008
RBP: 00007f1d2b810b39 R08: 0000000000000000 R09: 0000000000000000
R10: 00000000000004eb R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007f1d2b9b6160 R15: 00007ffe1f6f6078
</TASK>

The buggy address belongs to the virtual mapping at
[ffffc90003c48000, ffffc90003c51000) created by:
kernel_clone+0xfc/0x960 kernel/fork.c:2599

The buggy address belongs to the physical page:
page: refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x7a08a
memcg:ffff888030708182
flags: 0xfff00000000000(node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000000000 0000000000000000 dead000000000122 0000000000000000
raw: 0000000000000000 0000000000000000 00000001ffffffff ffff888030708182
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 0, migratetype Unmovable, gfp_mask 0x2dc2(GFP_KERNEL|__GFP_HIGHMEM|__GFP_ZERO|__GFP_NOWARN), pid 10955, tgid 10955 (syz-executor), ts 718165221630, free_ts 659282899784
set_page_owner include/linux/page_owner.h:32 [inline]
post_alloc_hook+0x1c0/0x230 mm/page_alloc.c:1704
prep_new_page mm/page_alloc.c:1712 [inline]
get_page_from_freelist+0x1321/0x3890 mm/page_alloc.c:3669
__alloc_frozen_pages_noprof+0x261/0x23f0 mm/page_alloc.c:4959
alloc_pages_mpol+0x1fb/0x550 mm/mempolicy.c:2419
alloc_frozen_pages_noprof mm/mempolicy.c:2490 [inline]
alloc_pages_noprof+0x131/0x390 mm/mempolicy.c:2510
vm_area_alloc_pages mm/vmalloc.c:3634 [inline]
__vmalloc_area_node mm/vmalloc.c:3712 [inline]
__vmalloc_node_range_noprof+0x72f/0x14b0 mm/vmalloc.c:3885
__vmalloc_node_noprof+0xad/0xf0 mm/vmalloc.c:3948
alloc_thread_stack_node kernel/fork.c:317 [inline]
dup_task_struct kernel/fork.c:877 [inline]
copy_process+0x2c70/0x76a0 kernel/fork.c:1999
kernel_clone+0xfc/0x960 kernel/fork.c:2599
__do_sys_clone3+0x212/0x290 kernel/fork.c:2903
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xcd/0x4c0 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
page last free pid 55 tgid 55 stack trace:
reset_page_owner include/linux/page_owner.h:25 [inline]
free_pages_prepare mm/page_alloc.c:1248 [inline]
__free_frozen_pages+0x7fe/0x1180 mm/page_alloc.c:2706
kasan_depopulate_vmalloc_pte+0x5f/0x80 mm/kasan/shadow.c:472
apply_to_pte_range mm/memory.c:3032 [inline]
apply_to_pmd_range mm/memory.c:3076 [inline]
apply_to_pud_range mm/memory.c:3112 [inline]
apply_to_p4d_range mm/memory.c:3148 [inline]
__apply_to_page_range+0xa92/0x1350 mm/memory.c:3184
kasan_release_vmalloc+0xd1/0xe0 mm/kasan/shadow.c:593
kasan_release_vmalloc_node mm/vmalloc.c:2241 [inline]
purge_vmap_node+0x1c4/0xa30 mm/vmalloc.c:2258
__purge_vmap_area_lazy+0xa06/0xc60 mm/vmalloc.c:2348
drain_vmap_area_work+0x27/0x40 mm/vmalloc.c:2382
process_one_work+0x9cf/0x1b70 kernel/workqueue.c:3238
process_scheduled_works kernel/workqueue.c:3321 [inline]
worker_thread+0x6c8/0xf10 kernel/workqueue.c:3402
kthread+0x3c5/0x780 kernel/kthread.c:464
ret_from_fork+0x5d7/0x6f0 arch/x86/kernel/process.c:148
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

Memory state around the buggy address:
ffffc90003c4fc80: 00 00 00 00 f1 f1 f1 f1 f1 f1 00 00 00 00 00 00
ffffc90003c4fd00: 00 00 00 f3 f3 f3 f3 f3 00 00 00 00 00 00 00 00
>ffffc90003c4fd80: 00 00 00 00 00 f1 f1 f1 f1 04 f3 f3 f3 00 00 00
^
ffffc90003c4fe00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 f1 f1
ffffc90003c4fe80: f1 f1 00 f2 f2 f2 00 00 f3 f3 00 00 00 00 00 00
==================================================================


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