syzbot


KMSAN: uninit-value in sctp_inq_pop (3)

Status: upstream: reported C repro on 2025/10/20 15:48
Subsystems: sctp
[Documentation on labels]
Reported-by: syzbot+d101e12bccd4095460e7@syzkaller.appspotmail.com
Fix commit: 51e5ad549c43 net: sctp: fix KMSAN uninit-value in sctp_inq_pop
Patched on: [ci-qemu-gce-upstream-auto ci-qemu-upstream ci-qemu-upstream-386 ci-qemu2-arm32 ci-qemu2-arm64 ci-qemu2-arm64-compat ci-qemu2-arm64-mte ci-snapshot-upstream-root ci-upstream-bpf-kasan-gce ci-upstream-bpf-next-kasan-gce ci-upstream-gce-arm64 ci-upstream-gce-leak ci-upstream-kasan-badwrites-root ci-upstream-kasan-gce ci-upstream-kasan-gce-386 ci-upstream-kasan-gce-root ci-upstream-kasan-gce-selinux-root ci-upstream-kasan-gce-smack-root ci-upstream-kmsan-gce-386-root ci-upstream-kmsan-gce-root ci-upstream-linux-next-kasan-gce-root ci-upstream-net-kasan-gce ci-upstream-net-this-kasan-gce ci-upstream-rust-kasan-gce ci2-upstream-fs ci2-upstream-kcsan-gce], missing on: [ci-qemu-native-arm64-kvm ci-qemu2-riscv64 ci2-upstream-usb]
First crash: 25d, last: 24d
Discussions (6)
Title Replies (including bot) Last reply
[PATCH v3] net: sctp: fix KMSAN uninit-value in sctp_inq_pop 3 (3) 2025/10/30 10:50
[PATCH v2] net: sctp: fix KMSAN uninit-value in sctp_inq_pop 3 (3) 2025/10/24 16:39
Re: [syzbot] [sctp?] KMSAN: uninit-value in sctp_inq_pop (3) 1 (2) 2025/10/24 07:37
[PATCH] net: sctp: fix KMSAN uninit-value in sctp_inq_pop 4 (4) 2025/10/23 17:49
[syzbot] [sctp?] KMSAN: uninit-value in sctp_inq_pop (3) 0 (3) 2025/10/22 18:00
Re: [syzbot] [sctp?] KMSAN: uninit-value in sctp_inq_pop (3) 1 (2) 2025/10/22 11:53
Similar bugs (2)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream KMSAN: uninit-value in sctp_inq_pop sctp 7 3 1601d 1641d 0/29 auto-closed as invalid on 2021/10/24 08:36
upstream KMSAN: uninit-value in sctp_inq_pop (2) sctp 7 C 4089 91d 1405d 29/29 fixed on 2025/10/09 01:15
Last patch testing requests (5)
Created Duration User Patch Repo Result
2025/10/24 06:34 48m vnranganath.20@gmail.com patch upstream OK log
2025/10/23 17:21 22m vnranganath.20@gmail.com patch upstream error
2025/10/22 18:00 31m vnranganath.20@gmail.com patch upstream OK log
2025/10/22 11:13 25m vnranganath.20@gmail.com patch upstream report log
2025/10/22 09:20 44m vnranganath.20@gmail.com patch upstream error

Sample crash report:
=====================================================
BUG: KMSAN: uninit-value in sctp_inq_pop+0x14dc/0x19e0 net/sctp/inqueue.c:211
 sctp_inq_pop+0x14dc/0x19e0 net/sctp/inqueue.c:211
 sctp_assoc_bh_rcv+0x1a0/0xbc0 net/sctp/associola.c:980
 sctp_inq_push+0x2a6/0x350 net/sctp/inqueue.c:88
 sctp_backlog_rcv+0x3c7/0xda0 net/sctp/input.c:331
 sk_backlog_rcv+0x142/0x420 include/net/sock.h:1158
 __release_sock+0x1ef/0x380 net/core/sock.c:3180
 release_sock+0x6b/0x270 net/core/sock.c:3735
 sctp_sendmsg+0x3a2b/0x49f0 net/sctp/socket.c:2036
 inet_sendmsg+0x26c/0x2a0 net/ipv4/af_inet.c:853
 sock_sendmsg_nosec net/socket.c:727 [inline]
 __sock_sendmsg+0x278/0x3d0 net/socket.c:742
 sock_sendmsg+0x170/0x280 net/socket.c:765
 splice_to_socket+0x10e6/0x1a60 fs/splice.c:886
 do_splice_from fs/splice.c:938 [inline]
 do_splice+0x1fd2/0x30d0 fs/splice.c:1351
 __do_splice fs/splice.c:1433 [inline]
 __do_sys_splice fs/splice.c:1636 [inline]
 __se_sys_splice+0x549/0x8c0 fs/splice.c:1618
 __x64_sys_splice+0x114/0x1a0 fs/splice.c:1618
 x64_sys_call+0x3140/0x3e30 arch/x86/include/generated/asm/syscalls_64.h:276
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xd9/0xfa0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Uninit was stored to memory at:
 sctp_inq_pop+0x144a/0x19e0 net/sctp/inqueue.c:207
 sctp_assoc_bh_rcv+0x1a0/0xbc0 net/sctp/associola.c:980
 sctp_inq_push+0x2a6/0x350 net/sctp/inqueue.c:88
 sctp_backlog_rcv+0x3c7/0xda0 net/sctp/input.c:331
 sk_backlog_rcv+0x142/0x420 include/net/sock.h:1158
 __release_sock+0x1ef/0x380 net/core/sock.c:3180
 release_sock+0x6b/0x270 net/core/sock.c:3735
 sctp_sendmsg+0x3a2b/0x49f0 net/sctp/socket.c:2036
 inet_sendmsg+0x26c/0x2a0 net/ipv4/af_inet.c:853
 sock_sendmsg_nosec net/socket.c:727 [inline]
 __sock_sendmsg+0x278/0x3d0 net/socket.c:742
 sock_sendmsg+0x170/0x280 net/socket.c:765
 splice_to_socket+0x10e6/0x1a60 fs/splice.c:886
 do_splice_from fs/splice.c:938 [inline]
 do_splice+0x1fd2/0x30d0 fs/splice.c:1351
 __do_splice fs/splice.c:1433 [inline]
 __do_sys_splice fs/splice.c:1636 [inline]
 __se_sys_splice+0x549/0x8c0 fs/splice.c:1618
 __x64_sys_splice+0x114/0x1a0 fs/splice.c:1618
 x64_sys_call+0x3140/0x3e30 arch/x86/include/generated/asm/syscalls_64.h:276
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xd9/0xfa0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Uninit was created at:
 slab_post_alloc_hook mm/slub.c:4969 [inline]
 slab_alloc_node mm/slub.c:5272 [inline]
 kmem_cache_alloc_node_noprof+0x989/0x16b0 mm/slub.c:5324
 kmalloc_reserve+0x13c/0x4b0 net/core/skbuff.c:579
 __alloc_skb+0x347/0x7d0 net/core/skbuff.c:670
 alloc_skb include/linux/skbuff.h:1383 [inline]
 sctp_packet_transmit+0x44b/0x46d0 net/sctp/output.c:598
 sctp_outq_flush_transports net/sctp/outqueue.c:1173 [inline]
 sctp_outq_flush+0x1c7d/0x67c0 net/sctp/outqueue.c:1221
 sctp_outq_uncork+0x9e/0xc0 net/sctp/outqueue.c:764
 sctp_cmd_interpreter net/sctp/sm_sideeffect.c:-1 [inline]
 sctp_side_effects net/sctp/sm_sideeffect.c:1204 [inline]
 sctp_do_sm+0x8c8e/0x9720 net/sctp/sm_sideeffect.c:1175
 sctp_primitive_SEND+0xd7/0x110 net/sctp/primitive.c:163
 sctp_sendmsg_to_asoc+0x1db8/0x2250 net/sctp/socket.c:1873
 sctp_sendmsg+0x3910/0x49f0 net/sctp/socket.c:2031
 inet_sendmsg+0x26c/0x2a0 net/ipv4/af_inet.c:853
 sock_sendmsg_nosec net/socket.c:727 [inline]
 __sock_sendmsg+0x278/0x3d0 net/socket.c:742
 sock_sendmsg+0x170/0x280 net/socket.c:765
 splice_to_socket+0x10e6/0x1a60 fs/splice.c:886
 do_splice_from fs/splice.c:938 [inline]
 do_splice+0x1fd2/0x30d0 fs/splice.c:1351
 __do_splice fs/splice.c:1433 [inline]
 __do_sys_splice fs/splice.c:1636 [inline]
 __se_sys_splice+0x549/0x8c0 fs/splice.c:1618
 __x64_sys_splice+0x114/0x1a0 fs/splice.c:1618
 x64_sys_call+0x3140/0x3e30 arch/x86/include/generated/asm/syscalls_64.h:276
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xd9/0xfa0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

CPU: 0 UID: 0 PID: 6071 Comm: syz.0.17 Not tainted syzkaller #0 PREEMPT(none) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
=====================================================

Crashes (9):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/10/20 03:59 upstream d9043c79ba68 1c8c8cd8 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci-upstream-kmsan-gce-root KMSAN: uninit-value in sctp_inq_pop
2025/10/20 01:42 upstream d9043c79ba68 1c8c8cd8 .config console log report syz / log [disk image] [vmlinux] [kernel image] ci-upstream-kmsan-gce-root KMSAN: uninit-value in sctp_inq_pop
2025/10/20 11:32 upstream 211ddde0823f 1c8c8cd8 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kmsan-gce-root KMSAN: uninit-value in sctp_inq_pop
2025/10/20 11:31 upstream 211ddde0823f 1c8c8cd8 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kmsan-gce-root KMSAN: uninit-value in sctp_inq_pop
2025/10/19 20:49 upstream d9043c79ba68 1c8c8cd8 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kmsan-gce-root KMSAN: uninit-value in sctp_inq_pop
2025/10/19 20:48 upstream d9043c79ba68 1c8c8cd8 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kmsan-gce-root KMSAN: uninit-value in sctp_inq_pop
2025/10/19 20:43 upstream d9043c79ba68 1c8c8cd8 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kmsan-gce-root KMSAN: uninit-value in sctp_inq_pop
2025/10/19 20:37 upstream d9043c79ba68 1c8c8cd8 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kmsan-gce-root KMSAN: uninit-value in sctp_inq_pop
2025/10/19 20:37 upstream d9043c79ba68 1c8c8cd8 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kmsan-gce-root KMSAN: uninit-value in sctp_inq_pop
* Struck through repros no longer work on HEAD.