WARNING in stack_depot_save_flags (2)

Status: upstream: reported C repro on 2026/05/19 17:48
Subsystems: net
Labels: prio:low
[Documentation on labels]
Reported-by: syzbot+1827030ed7bc886dd0a5@syzkaller.appspotmail.com
First crash: 97d, last: 5d19h
✨ AI Jobs (2)
ID Workflow Result Correct Bug Created Started Finished Revision
9462fdab repro-c Reproduced: ✅ WARNING in stack_depot_save_flags (2) 2026/08/14 14:11 2026/08/14 14:11 2026/08/14 19:56 746171ee
deedeb77 assessment-security DenialOfService: ❌ Exploitable: ❌ FilesystemTrigger: ❌ NetworkTrigger: ❌ PeripheralTrigger: ❌ RemoteTrigger: ❌ Unprivileged: ❌ UserNamespace: ❌ VMGuestTrigger: ❌ VMHostTrigger: ❌ WARNING in stack_depot_save_flags (2) 2026/05/31 19:29 2026/05/31 19:29 2026/05/31 20:25 6b4a8443
Discussions (1)
Title Replies (including bot) Last reply
[syzbot] [net?] WARNING in stack_depot_save_flags (2) 0 (2) 2026/08/15 12:36
Similar bugs (1)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream WARNING in stack_depot_save_flags block -1 syz, C error error 1 852d 848d 0/29 auto-obsoleted due to no activity on 2024/07/30 08:07
Last patch testing requests (1)
Created Duration User Patch Repo Result
2026/08/15 11:43 16m nogikh@google.com upstream report job log log

Sample crash report:
------------[ cut here ]------------
Stack depot reached limit capacity
WARNING: lib/stackdepot.c:302 at depot_init_pool lib/stackdepot.c:302 [inline], CPU#1: syz-executor190/6024
WARNING: lib/stackdepot.c:302 at depot_pop_free_pool lib/stackdepot.c:371 [inline], CPU#1: syz-executor190/6024
WARNING: lib/stackdepot.c:302 at depot_alloc_stack lib/stackdepot.c:462 [inline], CPU#1: syz-executor190/6024
WARNING: lib/stackdepot.c:302 at stack_depot_save_flags+0x9a2/0x9d0 lib/stackdepot.c:706, CPU#1: syz-executor190/6024
Modules linked in:
CPU: 1 UID: 0 PID: 6024 Comm: syz-executor190 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
RIP: 0010:depot_init_pool lib/stackdepot.c:302 [inline]
RIP: 0010:depot_pop_free_pool lib/stackdepot.c:371 [inline]
RIP: 0010:depot_alloc_stack lib/stackdepot.c:462 [inline]
RIP: 0010:stack_depot_save_flags+0x9a2/0x9d0 lib/stackdepot.c:706
Code: 0b 90 eb bf 48 85 ed 74 c6 48 89 2d 80 32 6c 16 48 89 ea 31 ed e9 0b ff ff ff 39 c1 72 1f 48 85 d2 74 20 48 8d 3d 6e e9 f9 0b <67> 48 0f b9 3a 45 31 f6 48 85 ed 0f 85 37 fa ff ff eb 92 90 0f 0b
RSP: 0018:ffffc90003d5f240 EFLAGS: 00010086
RAX: 0000000000002000 RBX: 0000000000000000 RCX: 0000000000002000
RDX: ffff88804f060000 RSI: ffffffff8e387082 RDI: ffffffff914d07e0
RBP: 0000000000000000 R08: 0000000000000001 R09: 000000001f92056e
R10: 00000000000000a0 R11: 0000000000000000 R12: ffffc90003d5f298
R13: 000000000000000f R14: ffff88816cc056e0 R15: ffff88816cc056e0
FS:  0000555582e6b400(0000) GS:ffff8880d5cde000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000556e2ead1be0 CR3: 00000000368af000 CR4: 0000000000352ef0
Call Trace:
 <TASK>
 kasan_save_stack+0x3f/0x50 mm/kasan/common.c:58
 kasan_save_track+0x14/0x30 mm/kasan/common.c:78
 unpoison_slab_object mm/kasan/common.c:340 [inline]
 __kasan_slab_alloc+0x89/0x90 mm/kasan/common.c:366
 kasan_slab_alloc include/linux/kasan.h:253 [inline]
 slab_post_alloc_hook mm/slub.c:4584 [inline]
 slab_alloc_node mm/slub.c:4917 [inline]
 kmem_cache_alloc_node_noprof+0x27d/0x6b0 mm/slub.c:4989
 kmalloc_reserve+0x148/0x350 net/core/skbuff.c:615
 pskb_expand_head+0x249/0x10e0 net/core/skbuff.c:2312
 skb_ensure_writable+0x2e9/0x480 net/core/skbuff.c:6377
 __bpf_try_make_writable net/core/filter.c:1685 [inline]
 bpf_try_make_writable net/core/filter.c:1691 [inline]
 bpf_try_make_head_writable net/core/filter.c:1699 [inline]
 ____bpf_clone_redirect net/core/filter.c:2491 [inline]
 bpf_clone_redirect+0x1f7/0x500 net/core/filter.c:2460
 bpf_prog_93719f3005523967+0x168e/0x33be
 bpf_dispatcher_nop_func include/linux/bpf.h:1454 [inline]
 __bpf_prog_run include/linux/filter.h:724 [inline]
 bpf_prog_run include/linux/filter.h:731 [inline]
 bpf_test_run+0x39c/0xa40 net/bpf/test_run.c:422
 bpf_prog_test_run_skb+0x15c4/0x3540 net/bpf/test_run.c:1225
 bpf_prog_test_run kernel/bpf/syscall.c:4859 [inline]
 __sys_bpf+0x2a12/0x4e80 kernel/bpf/syscall.c:6436
 __do_sys_bpf kernel/bpf/syscall.c:6537 [inline]
 __se_sys_bpf kernel/bpf/syscall.c:6534 [inline]
 __x64_sys_bpf+0xce/0x140 kernel/bpf/syscall.c:6534
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x115/0x870 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fe84f88ff59
Code: c0 79 93 eb d5 48 8d 7c 1d 00 eb 99 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 d8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fff9fca9ef8 EFLAGS: 00000246 ORIG_RAX: 0000000000000141
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fe84f88ff59
RDX: 0000000000000098 RSI: 00007fff9fcaa040 RDI: 000000000000000a
RBP: 0000000d00000085 R08: 0000555582e74770 R09: 0000555582e74770
R10: 00007fe84f9181a0 R11: 0000000000000246 R12: 00000001000002b7
R13: 00000000000001ce R14: 0000555582e6c760 R15: 0000000000000e14
 </TASK>
----------------
Code disassembly (best guess):
   0:	0b 90 eb bf 48 85    	or     -0x7ab74015(%rax),%edx
   6:	ed                   	in     (%dx),%eax
   7:	74 c6                	je     0xffffffcf
   9:	48 89 2d 80 32 6c 16 	mov    %rbp,0x166c3280(%rip)        # 0x166c3290
  10:	48 89 ea             	mov    %rbp,%rdx
  13:	31 ed                	xor    %ebp,%ebp
  15:	e9 0b ff ff ff       	jmp    0xffffff25
  1a:	39 c1                	cmp    %eax,%ecx
  1c:	72 1f                	jb     0x3d
  1e:	48 85 d2             	test   %rdx,%rdx
  21:	74 20                	je     0x43
  23:	48 8d 3d 6e e9 f9 0b 	lea    0xbf9e96e(%rip),%rdi        # 0xbf9e998
* 2a:	67 48 0f b9 3a       	ud1    (%edx),%rdi <-- trapping instruction
  2f:	45 31 f6             	xor    %r14d,%r14d
  32:	48 85 ed             	test   %rbp,%rbp
  35:	0f 85 37 fa ff ff    	jne    0xfffffa72
  3b:	eb 92                	jmp    0xffffffcf
  3d:	90                   	nop
  3e:	0f 0b                	ud2

Crashes (2):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/08/15 12:35 upstream 15ef2f78c49d 9cd3beaa .config console log report C ci-qemu-upstream WARNING in stack_depot_save_flags
2026/05/15 17:46 upstream 70eda68668d1 9cd3beaa .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream WARNING in stack_depot_save_flags
* Struck through repros no longer work on HEAD.