From: Thomas Gleixner <tglx@kernel.org>
To: syzbot <syzbot+5fca9514ef36ad94d973@syzkaller.appspotmail.com>,
jstultz@google.com, linux-kernel@vger.kernel.org,
sboyd@kernel.org, syzkaller-bugs@googlegroups.com
Cc: Alexander Potapenko <glider@google.com>,
Marco Elver <elver@google.com>,
kasan-dev@googlegroups.com
Subject: Re: [syzbot] [kernel?] KMSAN: uninit-value in timespec64_add_safe
Date: Sun, 08 Mar 2026 10:32:30 +0100 [thread overview]
Message-ID: <874imq3bv5.ffs@tglx> (raw)
In-Reply-To: <69aa4169.050a0220.13f275.0007.GAE@google.com>
On Thu, Mar 05 2026 at 18:52, syzbot wrote:
> udevd[5131]: starting eudev-3.2.14
> =====================================================
> BUG: KMSAN: uninit-value in set_normalized_timespec64 kernel/time/time.c:492 [inline]
> BUG: KMSAN: uninit-value in timespec64_add_safe+0x4b4/0x520 kernel/time/time.c:846
> set_normalized_timespec64 kernel/time/time.c:492 [inline]
> timespec64_add_safe+0x4b4/0x520 kernel/time/time.c:846
> ep_timeout_to_timespec fs/eventpoll.c:1872 [inline]
> __do_sys_epoll_wait fs/eventpoll.c:2471 [inline]
> __se_sys_epoll_wait fs/eventpoll.c:2465 [inline]
> __x64_sys_epoll_wait+0x1fa/0x3a0 fs/eventpoll.c:2465
> x64_sys_call+0x2ece/0x3ea0 arch/x86/include/generated/asm/syscalls_64.h:233
> 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
>
> Local variable now.i.i.i created at:
> ep_timeout_to_timespec fs/eventpoll.c:1857 [inline]
> __do_sys_epoll_wait fs/eventpoll.c:2471 [inline]
> __se_sys_epoll_wait fs/eventpoll.c:2465 [inline]
> __x64_sys_epoll_wait+0xcf/0x3a0 fs/eventpoll.c:2465
> x64_sys_call+0x2ece/0x3ea0 arch/x86/include/generated/asm/syscalls_64.h:233
This lacks:
Local variable now.i.i.i initialized at:
ktime_get_ts64(&now); <---- HERE
Right before the timespec64_add_safe() invocation
*to = timespec64_add_safe(now, *to);
KMSAN confused itself....
Thanks,
tglx
prev parent reply other threads:[~2026-03-08 9:32 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-03-06 2:52 [syzbot] [kernel?] KMSAN: uninit-value in timespec64_add_safe syzbot
2026-03-08 9:32 ` Thomas Gleixner [this message]
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