[syzbot] [bpf?] KMSAN: uninit-value in handle_bug
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syzbot
Dec 6, 2025, 9:30:34 AM12/6/25
to and...@kernel.org, a...@kernel.org, b...@vger.kernel.org, dan...@iogearbox.net, edd...@gmail.com, hao...@google.com, john.fa...@gmail.com, jo...@kernel.org, kps...@kernel.org, linux-...@vger.kernel.org, marti...@linux.dev, s...@fomichev.me, so...@kernel.org, syzkall...@googlegroups.com, yongho...@linux.dev
Hello,
syzbot found the following issue on:
HEAD commit: cc25df3e2e22 Merge tag 'for-6.19/block-20251201' of git://..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=16c2eab4580000
kernel config: https://syzkaller.appspot.com/x/.config?x=6c445efc9db431cb
dashboard link: https://syzkaller.appspot.com/bug?extid=ba80855313e6fa65717a
compiler: Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8
Unfortunately, I don't have any reproducer for this issue yet.
Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/a1afac06cfc1/disk-cc25df3e.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/7bd5369ac00a/vmlinux-cc25df3e.xz
kernel image: https://storage.googleapis.com/syzbot-assets/e183dedd04c6/bzImage-cc25df3e.xz
IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+ba8085...@syzkaller.appspotmail.com
------------[ cut here ]------------
=====================================================
BUG: KMSAN: uninit-value in vsnprintf+0x15d9/0x1b30 lib/vsprintf.c:2911
vsnprintf+0x15d9/0x1b30 lib/vsprintf.c:2911
vprintk_store+0x3ae/0x1530 kernel/printk/printk.c:2255
vprintk_emit+0x27b/0xc50 kernel/printk/printk.c:2402
vprintk_default+0x3f/0x50 kernel/printk/printk.c:2441
vprintk+0x36/0x50 kernel/printk/printk_safe.c:82
__warn_printf lib/bug.c:187 [inline]
__report_bug+0xa53/0xe80 lib/bug.c:240
report_bug_entry+0x148/0x1d0 lib/bug.c:265
handle_bug+0xe1/0x230 arch/x86/kernel/traps.c:430
exc_invalid_op+0x1f/0x50 arch/x86/kernel/traps.c:489
asm_exc_invalid_op+0x1f/0x30 arch/x86/include/asm/idtentry.h:616
reg_bounds_sanity_check+0x577/0x1450 kernel/bpf/verifier.c:2742
reg_set_min_max+0x3be/0x450 kernel/bpf/verifier.c:16572
check_cond_jmp_op+0x3a87/0x5380 kernel/bpf/verifier.c:17016
do_check_insn kernel/bpf/verifier.c:20441 [inline]
do_check+0x23ef/0x16a50 kernel/bpf/verifier.c:20581
do_check_common+0x2217/0x3370 kernel/bpf/verifier.c:23865
do_check_main kernel/bpf/verifier.c:23948 [inline]
bpf_check+0x1e78c/0x27610 kernel/bpf/verifier.c:25255
bpf_prog_load+0x2af6/0x3100 kernel/bpf/syscall.c:3088
__sys_bpf+0x7df/0xeb0 kernel/bpf/syscall.c:6164
__do_sys_bpf kernel/bpf/syscall.c:6274 [inline]
__se_sys_bpf kernel/bpf/syscall.c:6272 [inline]
__x64_sys_bpf+0xa4/0xf0 kernel/bpf/syscall.c:6272
x64_sys_call+0x31c3/0x3e70 arch/x86/include/generated/asm/syscalls_64.h:322
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xd9/0xf80 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
Uninit was stored to memory at:
vsnprintf+0x15d2/0x1b30 lib/vsprintf.c:-1
vprintk_store+0x3ae/0x1530 kernel/printk/printk.c:2255
vprintk_emit+0x27b/0xc50 kernel/printk/printk.c:2402
vprintk_default+0x3f/0x50 kernel/printk/printk.c:2441
vprintk+0x36/0x50 kernel/printk/printk_safe.c:82
__warn_printf lib/bug.c:187 [inline]
__report_bug+0xa53/0xe80 lib/bug.c:240
report_bug_entry+0x148/0x1d0 lib/bug.c:265
handle_bug+0xe1/0x230 arch/x86/kernel/traps.c:430
exc_invalid_op+0x1f/0x50 arch/x86/kernel/traps.c:489
asm_exc_invalid_op+0x1f/0x30 arch/x86/include/asm/idtentry.h:616
Local variable run_ctx.i created at:
__bpf_trace_run kernel/trace/bpf_trace.c:2063 [inline]
bpf_trace_run4+0xdf/0x590 kernel/trace/bpf_trace.c:2118
__bpf_trace_sched_switch+0x221/0x290 include/trace/events/sched.h:220
CPU: 1 UID: 0 PID: 23594 Comm: syz.7.5009 Tainted: G W syzkaller #0 PREEMPT(none)
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
=====================================================
---
This report is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzk...@googlegroups.com.
syzbot will keep track of this issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
If the report is already addressed, let syzbot know by replying with:
#syz fix: exact-commit-title
If you want to overwrite report's subsystems, reply with:
#syz set subsystems: new-subsystem
(See the list of subsystem names on the web dashboard)
If the report is a duplicate of another one, reply with:
#syz dup: exact-subject-of-another-report
If you want to undo deduplication, reply with:
#syz undup
syzbot found the following issue on:
HEAD commit: cc25df3e2e22 Merge tag 'for-6.19/block-20251201' of git://..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=16c2eab4580000
kernel config: https://syzkaller.appspot.com/x/.config?x=6c445efc9db431cb
dashboard link: https://syzkaller.appspot.com/bug?extid=ba80855313e6fa65717a
compiler: Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8
Unfortunately, I don't have any reproducer for this issue yet.
Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/a1afac06cfc1/disk-cc25df3e.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/7bd5369ac00a/vmlinux-cc25df3e.xz
kernel image: https://storage.googleapis.com/syzbot-assets/e183dedd04c6/bzImage-cc25df3e.xz
IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+ba8085...@syzkaller.appspotmail.com
------------[ cut here ]------------
=====================================================
BUG: KMSAN: uninit-value in vsnprintf+0x15d9/0x1b30 lib/vsprintf.c:2911
vsnprintf+0x15d9/0x1b30 lib/vsprintf.c:2911
vprintk_store+0x3ae/0x1530 kernel/printk/printk.c:2255
vprintk_emit+0x27b/0xc50 kernel/printk/printk.c:2402
vprintk_default+0x3f/0x50 kernel/printk/printk.c:2441
vprintk+0x36/0x50 kernel/printk/printk_safe.c:82
__warn_printf lib/bug.c:187 [inline]
__report_bug+0xa53/0xe80 lib/bug.c:240
report_bug_entry+0x148/0x1d0 lib/bug.c:265
handle_bug+0xe1/0x230 arch/x86/kernel/traps.c:430
exc_invalid_op+0x1f/0x50 arch/x86/kernel/traps.c:489
asm_exc_invalid_op+0x1f/0x30 arch/x86/include/asm/idtentry.h:616
reg_bounds_sanity_check+0x577/0x1450 kernel/bpf/verifier.c:2742
reg_set_min_max+0x3be/0x450 kernel/bpf/verifier.c:16572
check_cond_jmp_op+0x3a87/0x5380 kernel/bpf/verifier.c:17016
do_check_insn kernel/bpf/verifier.c:20441 [inline]
do_check+0x23ef/0x16a50 kernel/bpf/verifier.c:20581
do_check_common+0x2217/0x3370 kernel/bpf/verifier.c:23865
do_check_main kernel/bpf/verifier.c:23948 [inline]
bpf_check+0x1e78c/0x27610 kernel/bpf/verifier.c:25255
bpf_prog_load+0x2af6/0x3100 kernel/bpf/syscall.c:3088
__sys_bpf+0x7df/0xeb0 kernel/bpf/syscall.c:6164
__do_sys_bpf kernel/bpf/syscall.c:6274 [inline]
__se_sys_bpf kernel/bpf/syscall.c:6272 [inline]
__x64_sys_bpf+0xa4/0xf0 kernel/bpf/syscall.c:6272
x64_sys_call+0x31c3/0x3e70 arch/x86/include/generated/asm/syscalls_64.h:322
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xd9/0xf80 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
Uninit was stored to memory at:
vsnprintf+0x15d2/0x1b30 lib/vsprintf.c:-1
vprintk_store+0x3ae/0x1530 kernel/printk/printk.c:2255
vprintk_emit+0x27b/0xc50 kernel/printk/printk.c:2402
vprintk_default+0x3f/0x50 kernel/printk/printk.c:2441
vprintk+0x36/0x50 kernel/printk/printk_safe.c:82
__warn_printf lib/bug.c:187 [inline]
__report_bug+0xa53/0xe80 lib/bug.c:240
report_bug_entry+0x148/0x1d0 lib/bug.c:265
handle_bug+0xe1/0x230 arch/x86/kernel/traps.c:430
exc_invalid_op+0x1f/0x50 arch/x86/kernel/traps.c:489
asm_exc_invalid_op+0x1f/0x30 arch/x86/include/asm/idtentry.h:616
Local variable run_ctx.i created at:
__bpf_trace_run kernel/trace/bpf_trace.c:2063 [inline]
bpf_trace_run4+0xdf/0x590 kernel/trace/bpf_trace.c:2118
__bpf_trace_sched_switch+0x221/0x290 include/trace/events/sched.h:220
CPU: 1 UID: 0 PID: 23594 Comm: syz.7.5009 Tainted: G W syzkaller #0 PREEMPT(none)
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
=====================================================
---
This report is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzk...@googlegroups.com.
syzbot will keep track of this issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
If the report is already addressed, let syzbot know by replying with:
#syz fix: exact-commit-title
If you want to overwrite report's subsystems, reply with:
#syz set subsystems: new-subsystem
(See the list of subsystem names on the web dashboard)
If the report is a duplicate of another one, reply with:
#syz dup: exact-subject-of-another-report
If you want to undo deduplication, reply with:
#syz undup
syzbot
Mar 17, 2026, 2:45:29 AMMar 17
to and...@kernel.org, a...@kernel.org, b...@vger.kernel.org, dan...@iogearbox.net, edd...@gmail.com, hao...@google.com, john.fa...@gmail.com, jo...@kernel.org, kps...@kernel.org, linux-...@vger.kernel.org, marti...@linux.dev, s...@fomichev.me, so...@kernel.org, syzkall...@googlegroups.com, yongho...@linux.dev
syzbot has found a reproducer for the following issue on:
HEAD commit: 2d1373e4246d Merge tag 'for-7.0-rc4-tag' of git://git.kern..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=146bc4da580000
kernel config: https://syzkaller.appspot.com/x/.config?x=963de479f54c6dbb
dashboard link: https://syzkaller.appspot.com/bug?extid=ba80855313e6fa65717a
compiler: Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=14b4a8da580000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=16773406580000
Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/bef78207d3f7/disk-2d1373e4.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/35fd28ca5034/vmlinux-2d1373e4.xz
kernel image: https://storage.googleapis.com/syzbot-assets/c2b759faae9e/bzImage-2d1373e4.xz
IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+ba8085...@syzkaller.appspotmail.com
------------[ cut here ]------------
=====================================================
BUG: KMSAN: uninit-value in vsnprintf+0x15be/0x1b00 lib/vsprintf.c:2912
vsnprintf+0x15be/0x1b00 lib/vsprintf.c:2912
vprintk_store+0x350/0x1550 kernel/printk/printk.c:2307
vprintk_emit+0x2c8/0xba0 kernel/printk/printk.c:2455
vprintk_default+0x3f/0x50 kernel/printk/printk.c:2494
vprintk+0x36/0x50 kernel/printk/printk_safe.c:82
__warn_printf lib/bug.c:190 [inline]
__report_bug+0xa10/0xe00 lib/bug.c:244
report_bug_entry+0x17c/0x220 lib/bug.c:269
handle_bug+0xe5/0x230 arch/x86/kernel/traps.c:430
reg_set_min_max+0x34b/0x450 kernel/bpf/verifier.c:17159
check_cond_jmp_op+0x3bf5/0x5370 kernel/bpf/verifier.c:17609
do_check_insn kernel/bpf/verifier.c:21168 [inline]
do_check+0xc7e8/0x1add0 kernel/bpf/verifier.c:21308
do_check_common+0x2705/0x4270 kernel/bpf/verifier.c:24650
do_check_main kernel/bpf/verifier.c:24733 [inline]
bpf_check+0x1f159/0x27e90 kernel/bpf/verifier.c:26056
bpf_prog_load+0x2b41/0x3140 kernel/bpf/syscall.c:3089
__sys_bpf+0x8e0/0xee0 kernel/bpf/syscall.c:6228
__do_sys_bpf kernel/bpf/syscall.c:6341 [inline]
__se_sys_bpf kernel/bpf/syscall.c:6339 [inline]
__x64_sys_bpf+0xa4/0xf0 kernel/bpf/syscall.c:6339
x64_sys_call+0x13d0/0x3ea0 arch/x86/include/generated/asm/syscalls_64.h:322
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x134/0xf80 arch/x86/entry/syscall_64.c:94
vprintk_store+0x350/0x1550 kernel/printk/printk.c:2307
vprintk_emit+0x2c8/0xba0 kernel/printk/printk.c:2455
vprintk_default+0x3f/0x50 kernel/printk/printk.c:2494
vprintk+0x36/0x50 kernel/printk/printk_safe.c:82
__warn_printf lib/bug.c:190 [inline]
__report_bug+0xa10/0xe00 lib/bug.c:244
report_bug_entry+0x17c/0x220 lib/bug.c:269
handle_bug+0xe5/0x230 arch/x86/kernel/traps.c:430
try_charge_memcg+0x63/0x1c20 mm/memcontrol.c:2367
obj_cgroup_charge_pages+0x69/0x330 mm/memcontrol.c:2857
CPU: 1 UID: 0 PID: 5997 Comm: syz.0.17 Not tainted syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
=====================================================
---
If you want syzbot to run the reproducer, reply with:
#syz test: git://repo/address.git branch-or-commit-hash
If you attach or paste a git patch, syzbot will apply it before testing.
HEAD commit: 2d1373e4246d Merge tag 'for-7.0-rc4-tag' of git://git.kern..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=146bc4da580000
kernel config: https://syzkaller.appspot.com/x/.config?x=963de479f54c6dbb
dashboard link: https://syzkaller.appspot.com/bug?extid=ba80855313e6fa65717a
compiler: Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=14b4a8da580000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=16773406580000
Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/bef78207d3f7/disk-2d1373e4.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/35fd28ca5034/vmlinux-2d1373e4.xz
kernel image: https://storage.googleapis.com/syzbot-assets/c2b759faae9e/bzImage-2d1373e4.xz
IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+ba8085...@syzkaller.appspotmail.com
------------[ cut here ]------------
=====================================================
vsnprintf+0x15be/0x1b00 lib/vsprintf.c:2912
vprintk_store+0x350/0x1550 kernel/printk/printk.c:2307
vprintk_emit+0x2c8/0xba0 kernel/printk/printk.c:2455
vprintk_default+0x3f/0x50 kernel/printk/printk.c:2494
vprintk+0x36/0x50 kernel/printk/printk_safe.c:82
__warn_printf lib/bug.c:190 [inline]
__report_bug+0xa10/0xe00 lib/bug.c:244
report_bug_entry+0x17c/0x220 lib/bug.c:269
handle_bug+0xe5/0x230 arch/x86/kernel/traps.c:430
exc_invalid_op+0x1f/0x50 arch/x86/kernel/traps.c:489
asm_exc_invalid_op+0x1f/0x30 arch/x86/include/asm/idtentry.h:616
reg_bounds_sanity_check+0x571/0x14e0 kernel/bpf/verifier.c:2817
asm_exc_invalid_op+0x1f/0x30 arch/x86/include/asm/idtentry.h:616
reg_set_min_max+0x34b/0x450 kernel/bpf/verifier.c:17159
check_cond_jmp_op+0x3bf5/0x5370 kernel/bpf/verifier.c:17609
do_check_insn kernel/bpf/verifier.c:21168 [inline]
do_check+0xc7e8/0x1add0 kernel/bpf/verifier.c:21308
do_check_common+0x2705/0x4270 kernel/bpf/verifier.c:24650
do_check_main kernel/bpf/verifier.c:24733 [inline]
bpf_check+0x1f159/0x27e90 kernel/bpf/verifier.c:26056
bpf_prog_load+0x2b41/0x3140 kernel/bpf/syscall.c:3089
__sys_bpf+0x8e0/0xee0 kernel/bpf/syscall.c:6228
__do_sys_bpf kernel/bpf/syscall.c:6341 [inline]
__se_sys_bpf kernel/bpf/syscall.c:6339 [inline]
__x64_sys_bpf+0xa4/0xf0 kernel/bpf/syscall.c:6339
x64_sys_call+0x13d0/0x3ea0 arch/x86/include/generated/asm/syscalls_64.h:322
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x134/0xf80 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
Uninit was stored to memory at:
vsnprintf+0x15b7/0x1b00 lib/vsprintf.c:-1
Uninit was stored to memory at:
vprintk_store+0x350/0x1550 kernel/printk/printk.c:2307
vprintk_emit+0x2c8/0xba0 kernel/printk/printk.c:2455
vprintk_default+0x3f/0x50 kernel/printk/printk.c:2494
vprintk+0x36/0x50 kernel/printk/printk_safe.c:82
__warn_printf lib/bug.c:190 [inline]
__report_bug+0xa10/0xe00 lib/bug.c:244
report_bug_entry+0x17c/0x220 lib/bug.c:269
handle_bug+0xe5/0x230 arch/x86/kernel/traps.c:430
exc_invalid_op+0x1f/0x50 arch/x86/kernel/traps.c:489
asm_exc_invalid_op+0x1f/0x30 arch/x86/include/asm/idtentry.h:616
Local variable pflags created at:
asm_exc_invalid_op+0x1f/0x30 arch/x86/include/asm/idtentry.h:616
try_charge_memcg+0x63/0x1c20 mm/memcontrol.c:2367
obj_cgroup_charge_pages+0x69/0x330 mm/memcontrol.c:2857
CPU: 1 UID: 0 PID: 5997 Comm: syz.0.17 Not tainted syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
=====================================================
---
If you want syzbot to run the reproducer, reply with:
#syz test: git://repo/address.git branch-or-commit-hash
If you attach or paste a git patch, syzbot will apply it before testing.
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