syzbot


KMSAN: uninit-value in bstr_printf (2)

Status: upstream: reported C repro on 2024/06/12 16:26
Subsystems: bpf
[Documentation on labels]
Reported-by: syzbot+3d98610f9d9bdb4a57ce@syzkaller.appspotmail.com
First crash: 34d, last: 29d
Discussions (1)
Title Replies (including bot) Last reply
[syzbot] [bpf?] KMSAN: uninit-value in bstr_printf (2) 0 (1) 2024/06/12 16:26
Similar bugs (1)
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream KMSAN: uninit-value in bstr_printf bpf 4 51d 142d 0/27 closed as dup on 2024/04/09 05:33
Last patch testing requests (1)
Created Duration User Patch Repo Result
2024/06/27 13:39 22m retest repro upstream error

Sample crash report:
=====================================================
BUG: KMSAN: uninit-value in bstr_printf+0x19df/0x1b50 lib/vsprintf.c:3334
 bstr_printf+0x19df/0x1b50 lib/vsprintf.c:3334
 ____bpf_snprintf kernel/bpf/helpers.c:1064 [inline]
 bpf_snprintf+0x1c8/0x360 kernel/bpf/helpers.c:1044
 ___bpf_prog_run+0x13fe/0xe0f0 kernel/bpf/core.c:1997
 __bpf_prog_run288+0xb5/0xe0 kernel/bpf/core.c:2237
 bpf_dispatcher_nop_func include/linux/bpf.h:1234 [inline]
 __bpf_prog_run include/linux/filter.h:657 [inline]
 bpf_prog_run include/linux/filter.h:664 [inline]
 bpf_test_run+0x499/0xc30 net/bpf/test_run.c:425
 bpf_prog_test_run_skb+0x14ea/0x1f20 net/bpf/test_run.c:1058
 bpf_prog_test_run+0x6b7/0xad0 kernel/bpf/syscall.c:4269
 __sys_bpf+0x6aa/0xd90 kernel/bpf/syscall.c:5678
 __do_sys_bpf kernel/bpf/syscall.c:5767 [inline]
 __se_sys_bpf kernel/bpf/syscall.c:5765 [inline]
 __x64_sys_bpf+0xa0/0xe0 kernel/bpf/syscall.c:5765
 x64_sys_call+0x96b/0x3b50 arch/x86/include/generated/asm/syscalls_64.h:322
 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 stored to memory at:
 bpf_bprintf_prepare+0x1393/0x23c0 kernel/bpf/helpers.c:1027
 ____bpf_snprintf kernel/bpf/helpers.c:1060 [inline]
 bpf_snprintf+0x141/0x360 kernel/bpf/helpers.c:1044
 ___bpf_prog_run+0x13fe/0xe0f0 kernel/bpf/core.c:1997
 __bpf_prog_run288+0xb5/0xe0 kernel/bpf/core.c:2237
 bpf_dispatcher_nop_func include/linux/bpf.h:1234 [inline]
 __bpf_prog_run include/linux/filter.h:657 [inline]
 bpf_prog_run include/linux/filter.h:664 [inline]
 bpf_test_run+0x499/0xc30 net/bpf/test_run.c:425
 bpf_prog_test_run_skb+0x14ea/0x1f20 net/bpf/test_run.c:1058
 bpf_prog_test_run+0x6b7/0xad0 kernel/bpf/syscall.c:4269
 __sys_bpf+0x6aa/0xd90 kernel/bpf/syscall.c:5678
 __do_sys_bpf kernel/bpf/syscall.c:5767 [inline]
 __se_sys_bpf kernel/bpf/syscall.c:5765 [inline]
 __x64_sys_bpf+0xa0/0xe0 kernel/bpf/syscall.c:5765
 x64_sys_call+0x96b/0x3b50 arch/x86/include/generated/asm/syscalls_64.h:322
 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

Local variable stack created at:
 __bpf_prog_run288+0x45/0xe0 kernel/bpf/core.c:2237
 bpf_dispatcher_nop_func include/linux/bpf.h:1234 [inline]
 __bpf_prog_run include/linux/filter.h:657 [inline]
 bpf_prog_run include/linux/filter.h:664 [inline]
 bpf_test_run+0x499/0xc30 net/bpf/test_run.c:425

CPU: 1 PID: 5042 Comm: syz-executor235 Not tainted 6.9.0-syzkaller-02707-g614da38e2f7a #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/02/2024
=====================================================

Crashes (5):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2024/06/08 22:16 upstream 614da38e2f7a 82c05ab8 .config strace log report syz / log C [disk image] [vmlinux] [kernel image] ci-upstream-kmsan-gce-root KMSAN: uninit-value in bstr_printf
2024/06/13 12:46 upstream 614da38e2f7a 2aa5052f .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kmsan-gce-root KMSAN: uninit-value in bstr_printf
2024/06/13 12:46 upstream 614da38e2f7a 2aa5052f .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kmsan-gce-root KMSAN: uninit-value in bstr_printf
2024/06/08 16:26 upstream 614da38e2f7a 82c05ab8 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kmsan-gce-root KMSAN: uninit-value in bstr_printf
2024/06/08 16:20 upstream 614da38e2f7a 82c05ab8 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kmsan-gce-root KMSAN: uninit-value in bstr_printf
* Struck through repros no longer work on HEAD.