syzbot


KASAN: stack-out-of-bounds Read in __xfrm_dst_hash

Status: upstream: reported C repro on 2026/01/31 15:19
Bug presence: origin:lts
[Documentation on labels]
Reported-by: syzbot+9edcd664260dd9942e34@syzkaller.appspotmail.com
First crash: 8d13h, last: 8d13h
Bug presence (2)
Date Name Commit Repro Result
2026/01/31 lts (merge base) 278455a82245 C [report] KASAN: stack-out-of-bounds Read in __xfrm_dst_hash
2026/01/31 upstream (ToT) ad9a728a3388 C Didn't crash
Similar bugs (2)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
android-5-10 KASAN: stack-out-of-bounds Read in __xfrm_dst_hash (2) 17 C error 2 36d 50d 0/2 upstream: reported C repro on 2025/12/20 23:50
android-5-10 KASAN: stack-out-of-bounds Read in __xfrm_dst_hash 17 1 362d 362d 0/2 auto-obsoleted due to no activity on 2025/05/12 11:45

Sample crash report:
==================================================================
BUG: KASAN: stack-out-of-bounds in jhash2 include/linux/jhash.h:138 [inline]
BUG: KASAN: stack-out-of-bounds in __xfrm6_addr_hash net/xfrm/xfrm_hash.h:16 [inline]
BUG: KASAN: stack-out-of-bounds in __xfrm6_daddr_saddr_hash net/xfrm/xfrm_hash.h:29 [inline]
BUG: KASAN: stack-out-of-bounds in __xfrm_dst_hash+0x399/0x480 net/xfrm/xfrm_hash.h:95
Read of size 4 at addr ffffc900001d0ad8 by task swapper/1/0

CPU: 1 PID: 0 Comm: swapper/1 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
Call Trace:
 <IRQ>
 __dump_stack+0x21/0x30 lib/dump_stack.c:88
 dump_stack_lvl+0x110/0x170 lib/dump_stack.c:106
 print_address_description+0x7f/0x2c0 mm/kasan/report.c:248
 __kasan_report mm/kasan/report.c:427 [inline]
 kasan_report+0xf1/0x140 mm/kasan/report.c:444
 __asan_report_load4_noabort+0x14/0x20 mm/kasan/report_generic.c:308
 jhash2 include/linux/jhash.h:138 [inline]
 __xfrm6_addr_hash net/xfrm/xfrm_hash.h:16 [inline]
 __xfrm6_daddr_saddr_hash net/xfrm/xfrm_hash.h:29 [inline]
 __xfrm_dst_hash+0x399/0x480 net/xfrm/xfrm_hash.h:95
 xfrm_dst_hash net/xfrm/xfrm_state.c:63 [inline]
 xfrm_state_find+0x28a/0x2a10 net/xfrm/xfrm_state.c:1092
 xfrm_tmpl_resolve_one net/xfrm/xfrm_policy.c:2396 [inline]
 xfrm_tmpl_resolve net/xfrm/xfrm_policy.c:2441 [inline]
 xfrm_resolve_and_create_bundle+0x697/0x29f0 net/xfrm/xfrm_policy.c:2734
 xfrm_bundle_lookup net/xfrm/xfrm_policy.c:2969 [inline]
 xfrm_lookup_with_ifid+0x4e9/0x2080 net/xfrm/xfrm_policy.c:3100
 xfrm_lookup net/xfrm/xfrm_policy.c:3197 [inline]
 xfrm_lookup_route+0x3c/0x170 net/xfrm/xfrm_policy.c:3208
 ip_route_output_flow+0x1f8/0x2f0 net/ipv4/route.c:2905
 ip_route_output_ports include/net/route.h:169 [inline]
 igmpv3_newpack+0x280/0xcd0 net/ipv4/igmp.c:372
 add_grhead+0x75/0x2e0 net/ipv4/igmp.c:443
 add_grec+0x116c/0x1410 net/ipv4/igmp.c:577
 igmpv3_send_cr net/ipv4/igmp.c:714 [inline]
 igmp_ifc_timer_expire+0x89e/0xf80 net/ipv4/igmp.c:813
 call_timer_fn+0x38/0x290 kernel/time/timer.c:1457
 expire_timers kernel/time/timer.c:1502 [inline]
 __run_timers+0x650/0x9e0 kernel/time/timer.c:1773
 run_timer_softirq+0x6a/0xf0 kernel/time/timer.c:1786
 handle_softirqs+0x250/0x560 kernel/softirq.c:583
 __do_softirq kernel/softirq.c:621 [inline]
 invoke_softirq kernel/softirq.c:443 [inline]
 __irq_exit_rcu+0x52/0xf0 kernel/softirq.c:670
 irq_exit_rcu+0x9/0x10 kernel/softirq.c:682
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1108 [inline]
 sysvec_apic_timer_interrupt+0xa9/0xc0 arch/x86/kernel/apic/apic.c:1108
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x1b/0x20 arch/x86/include/asm/idtentry.h:676
RIP: 0010:default_idle+0xf/0x20 arch/x86/kernel/process.c:730
Code: ff 4c 89 f7 e8 d2 27 f5 fc e9 3d ff ff ff 00 00 cc cc 00 00 cc cc 00 00 cc cc 00 55 48 89 e5 66 90 0f 00 2d 93 93 51 00 fb f4 <5d> c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 55 48 89 e5 41
RSP: 0018:ffffc90000157d98 EFLAGS: 00000242
RAX: 0000000000002d8c RBX: ffff88810030a780 RCX: 0000000000002d8c
RDX: 0000000000000001 RSI: ffffffff85639520 RDI: ffffffff856394e0
RBP: ffffc90000157d98 R08: ffff8881f7138c73 R09: 1ffff1103ee2718e
R10: dffffc0000000000 R11: ffffed103ee2718f R12: 1ffff110200614f0
R13: 0000000000000001 R14: 0000000000000000 R15: dffffc0000000000
 arch_cpu_idle+0xa/0x10 arch/x86/kernel/process.c:721
 default_idle_call+0x71/0x1d0 kernel/sched/idle.c:112
 cpuidle_idle_call kernel/sched/idle.c:194 [inline]
 do_idle+0x1dc/0x570 kernel/sched/idle.c:306
 cpu_startup_entry+0x18/0x20 kernel/sched/idle.c:403
 start_secondary+0x2e6/0x3a0 arch/x86/kernel/smpboot.c:281
 secondary_startup_64_no_verify+0xb1/0xbb
 </TASK>


Memory state around the buggy address:
 ffffc900001d0980: f8 f8 f3 f3 f3 f3 f3 f3 00 00 00 00 00 00 00 00
 ffffc900001d0a00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffffc900001d0a80: f1 f1 f1 f1 00 00 00 00 00 00 00 f3 f3 f3 f3 f3
                                                    ^
 ffffc900001d0b00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffffc900001d0b80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
==================================================================
----------------
Code disassembly (best guess):
   0:	ff 4c 89 f7          	decl   -0x9(%rcx,%rcx,4)
   4:	e8 d2 27 f5 fc       	call   0xfcf527db
   9:	e9 3d ff ff ff       	jmp    0xffffff4b
   e:	00 00                	add    %al,(%rax)
  10:	cc                   	int3
  11:	cc                   	int3
  12:	00 00                	add    %al,(%rax)
  14:	cc                   	int3
  15:	cc                   	int3
  16:	00 00                	add    %al,(%rax)
  18:	cc                   	int3
  19:	cc                   	int3
  1a:	00 55 48             	add    %dl,0x48(%rbp)
  1d:	89 e5                	mov    %esp,%ebp
  1f:	66 90                	xchg   %ax,%ax
  21:	0f 00 2d 93 93 51 00 	verw   0x519393(%rip)        # 0x5193bb
  28:	fb                   	sti
  29:	f4                   	hlt
* 2a:	5d                   	pop    %rbp <-- trapping instruction
  2b:	c3                   	ret
  2c:	66 2e 0f 1f 84 00 00 	cs nopw 0x0(%rax,%rax,1)
  33:	00 00 00
  36:	0f 1f 44 00 00       	nopl   0x0(%rax,%rax,1)
  3b:	55                   	push   %rbp
  3c:	48 89 e5             	mov    %rsp,%rbp
  3f:	41                   	rex.B

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/01/31 15:18 android13-5.15-lts 7e1070528954 afc0c4d4 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-android-5-15 KASAN: stack-out-of-bounds Read in __xfrm_dst_hash
* Struck through repros no longer work on HEAD.