syzbot


KMSAN: uninit-value in ppp_async_push (3)

Status: upstream: reported C repro on 2024/07/04 16:33
Subsystems: ppp
[Documentation on labels]
Reported-by: syzbot+ec0723ba9605678b14bf@syzkaller.appspotmail.com
Fix commit: f2aeb7306a89 ppp: reject claimed-as-LCP but actually malformed packets
Patched on: [ci-qemu-upstream ci-qemu-upstream-386 ci-qemu2-arm32 ci-qemu2-arm64 ci-qemu2-arm64-compat ci-qemu2-arm64-mte ci-upstream-bpf-kasan-gce ci-upstream-bpf-next-kasan-gce 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 ci2-upstream-fs ci2-upstream-kcsan-gce ci2-upstream-net-next-test-gce], missing on: [ci-qemu-native-arm64-kvm ci-qemu2-riscv64 ci-upstream-gce-arm64 ci2-upstream-usb]
First crash: 58d, last: 58d
Discussions (2)
Title Replies (including bot) Last reply
[PATCH] net: ppp: reject claimed-as-LCP but actually malformed packets 6 (6) 2024/07/11 09:30
[syzbot] [ppp?] KMSAN: uninit-value in ppp_async_push (3) 0 (1) 2024/07/04 16:33
Similar bugs (2)
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream KMSAN: uninit-value in ppp_async_push (2) ppp C 323 883d 954d 20/27 fixed on 2022/03/08 16:11
upstream KMSAN: uninit-value in ppp_async_push ppp C 3187 1099d 1388d 0/27 closed as invalid on 2021/10/06 02:59
Last patch testing requests (1)
Created Duration User Patch Repo Result
2024/06/05 06:10 23m retest repro upstream error

Sample crash report:
=====================================================
BUG: KMSAN: uninit-value in ppp_async_encode drivers/net/ppp/ppp_async.c:548 [inline]
BUG: KMSAN: uninit-value in ppp_async_push+0xc05/0x2660 drivers/net/ppp/ppp_async.c:675
 ppp_async_encode drivers/net/ppp/ppp_async.c:548 [inline]
 ppp_async_push+0xc05/0x2660 drivers/net/ppp/ppp_async.c:675
 ppp_async_send+0x130/0x1b0 drivers/net/ppp/ppp_async.c:634
 ppp_push+0x220/0x22b0 drivers/net/ppp/ppp_generic.c:1883
 ppp_send_frame drivers/net/ppp/ppp_generic.c:1846 [inline]
 __ppp_xmit_process+0x123a/0x2780 drivers/net/ppp/ppp_generic.c:1646
 ppp_xmit_process+0x100/0x2b0 drivers/net/ppp/ppp_generic.c:1667
 ppp_write+0x63a/0x7d0 drivers/net/ppp/ppp_generic.c:521
 do_loop_readv_writev fs/read_write.c:764 [inline]
 vfs_writev+0xb0e/0x1450 fs/read_write.c:973
 do_pwritev fs/read_write.c:1072 [inline]
 __do_sys_pwritev fs/read_write.c:1119 [inline]
 __se_sys_pwritev fs/read_write.c:1114 [inline]
 __x64_sys_pwritev+0x2e5/0x500 fs/read_write.c:1114
 x64_sys_call+0x3539/0x3b50 arch/x86/include/generated/asm/syscalls_64.h:297
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xcf/0x1e0 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Uninit was created at:
 slab_post_alloc_hook mm/slub.c:3877 [inline]
 slab_alloc_node mm/slub.c:3918 [inline]
 kmem_cache_alloc_node+0x622/0xc90 mm/slub.c:3961
 kmalloc_reserve+0x13d/0x4a0 net/core/skbuff.c:577
 __alloc_skb+0x35b/0x7a0 net/core/skbuff.c:668
 alloc_skb include/linux/skbuff.h:1319 [inline]
 ppp_write+0xe5/0x7d0 drivers/net/ppp/ppp_generic.c:509
 do_loop_readv_writev fs/read_write.c:764 [inline]
 vfs_writev+0xb0e/0x1450 fs/read_write.c:973
 do_pwritev fs/read_write.c:1072 [inline]
 __do_sys_pwritev fs/read_write.c:1119 [inline]
 __se_sys_pwritev fs/read_write.c:1114 [inline]
 __x64_sys_pwritev+0x2e5/0x500 fs/read_write.c:1114
 x64_sys_call+0x3539/0x3b50 arch/x86/include/generated/asm/syscalls_64.h:297
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xcf/0x1e0 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

CPU: 1 PID: 5049 Comm: syz-executor420 Not tainted 6.9.0-syzkaller-02707-g614da38e2f7a #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/02/2024
=====================================================

Crashes (4):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2024/05/22 04:50 upstream 614da38e2f7a 1014eca7 .config strace log report syz C [disk image] [vmlinux] [kernel image] ci-upstream-kmsan-gce-root KMSAN: uninit-value in ppp_async_push
2024/05/22 00:59 upstream 614da38e2f7a 1014eca7 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kmsan-gce-root KMSAN: uninit-value in ppp_async_push
2024/05/22 00:59 upstream 614da38e2f7a 1014eca7 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kmsan-gce-root KMSAN: uninit-value in ppp_async_push
2024/05/22 06:03 upstream 101b7a97143a 1014eca7 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kmsan-gce-386-root KMSAN: uninit-value in ppp_async_push
* Struck through repros no longer work on HEAD.