UBSAN: shift-out-of-bounds in meta_int_apply_extras

Status: upstream: reported C repro on 2026/10/18 03:48
Reported-by: syzbot+7721fa414292e0f5af61@syzkaller.appspotmail.com
First crash: 2d07h, last: 2d05h
▶ ▼ Similar bugs (1)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
android-6-1 UBSAN: shift-out-of-bounds in meta_int_apply_extras -1 syz, C 3 9d04h 9d04h 0/2 upstream: reported C repro on 2026/10/11 05:45

Sample crash report:
device syzkaller0 entered promiscuous mode
================================================================================
UBSAN: shift-out-of-bounds in net/sched/em_meta.c:763:14
shift exponent 252 is too large for 64-bit type 'unsigned long'
CPU: 1 PID: 303 Comm: syz-executor236 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
Call Trace:
 <TASK>
 __dump_stack+0x21/0x30 lib/dump_stack.c:88
 dump_stack_lvl+0x110/0x170 lib/dump_stack.c:106
 dump_stack+0x15/0x20 lib/dump_stack.c:113
 ubsan_epilogue+0xe/0x40 lib/ubsan.c:151
 __ubsan_handle_shift_out_of_bounds+0x364/0x3f0 lib/ubsan.c:321
 meta_int_apply_extras+0x13d/0x150 net/sched/em_meta.c:763
 meta_get+0x1f3/0x3f0 net/sched/em_meta.c:838
 em_meta_match+0xec/0x2f0 net/sched/em_meta.c:850
 tcf_em_match net/sched/ematch.c:494 [inline]
 __tcf_em_tree_match+0x1cb/0x7a0 net/sched/ematch.c:520
 tcf_em_tree_match include/net/pkt_cls.h:463 [inline]
 basic_classify+0xd9/0x240 net/sched/cls_basic.c:48
 __tcf_classify net/sched/cls_api.c:1550 [inline]
 tcf_classify+0x154/0x410 net/sched/cls_api.c:1590
 sch_handle_ingress net/core/dev.c:5207 [inline]
 __netif_receive_skb_core+0x186b/0x2fb0 net/core/dev.c:5420
 __netif_receive_skb_list_core+0x24d/0x770 net/core/dev.c:5635
 __netif_receive_skb_list net/core/dev.c:5702 [inline]
 netif_receive_skb_list_internal+0x7f8/0xaa0 net/core/dev.c:5793
 gro_normal_list net/core/dev.c:5947 [inline]
 napi_complete_done+0x375/0x7a0 net/core/dev.c:6685
 napi_complete include/linux/netdevice.h:505 [inline]
 tun_get_user+0x265c/0x33e0 drivers/net/tun.c:1979
 tun_chr_write_iter+0x1ed/0x2f0 drivers/net/tun.c:2030
 call_write_iter include/linux/fs.h:2218 [inline]
 new_sync_write fs/read_write.c:507 [inline]
 vfs_write+0x831/0xfd0 fs/read_write.c:594
 ksys_write+0x14a/0x260 fs/read_write.c:647
 __do_sys_write fs/read_write.c:659 [inline]
 __se_sys_write fs/read_write.c:656 [inline]
 __x64_sys_write+0x7b/0x90 fs/read_write.c:656
 x64_sys_call+0x8ef/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:2
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7efe726870f9
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:00007fff7a5a7d48 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007fff7a5a7e78 RCX: 00007efe726870f9
RDX: 0000000000000066 RSI: 0000200000000000 RDI: 0000000000000003
RBP: 0000000000000001 R08: 00007fff7a5a7e78 R09: 00007fff7a5a7e78
R10: 00007fff7a5a7e78 R11: 0000000000000246 R12: 00007fff7a5a7e68
R13: 0000000000000002 R14: 00007efe72717ca0 R15: 0000000000000002
 </TASK>
================================================================================

Crashes (3):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/10/18 04:14 android13-5.15-lts ff23d765b06f 432c0077 .config strace log report syz / log C [disk image] [vmlinux] [kernel image] ci2-android-5-15 UBSAN: shift-out-of-bounds in meta_int_apply_extras
2026/10/18 03:37 android13-5.15-lts ff23d765b06f 432c0077 .config strace log report syz / log C [disk image] [vmlinux] [kernel image] ci2-android-5-15 UBSAN: shift-out-of-bounds in meta_int_apply_extras
2026/10/18 03:05 android13-5.15-lts ff23d765b06f 432c0077 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-15 UBSAN: shift-out-of-bounds in meta_int_apply_extras
* Struck through repros no longer work on HEAD.