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bh=1G3MekQgMVdwkAz8QZdfoDsQVqrzOU3Isg5G6JFJk70=; b=c7HwVXaXAoPccKBLP72b+Qcbs/fvfae0+AMWy0d2iie2Tx3/yVShL/bXaFORJwjrrqout4 /j4Rfk7MZaooCKV5wP/iH6GVo6wr/ce4J+rcoPlOQ6gdb2s5qER6EjprZi1Rh7ZF8J03vN 4+NQ/Rc8lQfuK0tHZy32INmbzfMW36NQbsHQEUQ7YwNBpdHCcXiodwyEXFwkB624ePxcEY wXgmhQ9ZwAwcz2gieJzKU2EaYptJGltQjxfG1/XQ7WPBhuHF250gxayjr4vTSkEEDKgY6J fPWpghay1vgx9Xlgxm7mP4WDFxTeK9BedtTEccByfslVmj3xUqH5TaWXtcTIxA== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1753371095; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=1G3MekQgMVdwkAz8QZdfoDsQVqrzOU3Isg5G6JFJk70=; b=BRw6ZFVpFFgUc0u8GEK5C3NVWTJiUHIMwf2BmcAJ3FLGvmjZar/BFJZPWzAhKfNeIGdagD VjKc2Vaa05V8a+Bg== To: syzbot , anna-maria@linutronix.de, frederic@kernel.org, linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com Cc: Alexander Potapenko , Marco Elver , Dmitry Vyukov Subject: Re: [syzbot] [kernel?] KMSAN: uninit-value in hrtimer_wakeup In-Reply-To: <68820e8e.a00a0220.2f88df.0022.GAE@google.com> References: <68820e8e.a00a0220.2f88df.0022.GAE@google.com> Date: Thu, 24 Jul 2025 17:31:35 +0200 Message-ID: <87cy9pr4fc.ffs@tglx> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain On Thu, Jul 24 2025 at 03:44, syzbot wrote: > HEAD commit: bf61759db409 Merge tag 'sched_ext-for-6.16-rc6-fixes' of g.. > git tree: upstream > console output: https://syzkaller.appspot.com/x/log.txt?x=1693938c580000 > kernel config: https://syzkaller.appspot.com/x/.config?x=5227c65742122bdd > dashboard link: https://syzkaller.appspot.com/bug?extid=e84a763987edd173d82f > compiler: Debian clang version 20.1.7 (++20250616065708+6146a88f6049-1~exp1~20250616065826.132), Debian LLD 20.1.7 > > Unfortunately, I don't have any reproducer for this issue yet. > > Downloadable assets: > disk image: https://storage.googleapis.com/syzbot-assets/c9e297bb553f/disk-bf61759d.raw.xz > vmlinux: https://storage.googleapis.com/syzbot-assets/7f2d1bf53414/vmlinux-bf61759d.xz > kernel image: https://storage.googleapis.com/syzbot-assets/9a4f67426eab/bzImage-bf61759d.xz > > IMPORTANT: if you fix the issue, please add the following tag to the commit: > Reported-by: syzbot+e84a763987edd173d82f@syzkaller.appspotmail.com > > ===================================================== > BUG: KMSAN: uninit-value in hrtimer_wakeup+0xcb/0xd0 kernel/time/hrtimer.c:1997 > hrtimer_wakeup+0xcb/0xd0 kernel/time/hrtimer.c:1997 ... > Local variable t created at: > hrtimer_nanosleep+0x48/0x480 kernel/time/hrtimer.c:2142 > common_nsleep+0x118/0x160 kernel/time/posix-timers.c:1353 This makes absolutely no sense. hrtimer_nanosleep() initializes the local variable struct hrtimer_sleeper t; in two steps: hrtimer_setup_sleeper_on_stack(&t, clockid, mode); hrtimer_set_expires_range_ns(&t.timer, rqtp, current->timer_slack_ns); and the complaint in hrtimer_wakeup() is: 1989 static enum hrtimer_restart hrtimer_wakeup(struct hrtimer *timer) 1990 { 1991 struct hrtimer_sleeper *t = 1992 container_of(timer, struct hrtimer_sleeper, timer); 1993 struct task_struct *task = t->task; 1994 1995 t->task = NULL; 1996 if (task) 1997 wake_up_process(task); <---- here 1998 1999 return HRTIMER_NORESTART; 2000 } t->task was initialized: 2027 static void __hrtimer_setup_sleeper(struct hrtimer_sleeper *sl, 2028 clockid_t clock_id, enum hrtimer_mode mode) 2029 { ... 2054 __hrtimer_setup(&sl->timer, hrtimer_wakeup, clock_id, mode); 2055 sl->task = current; <---- here 2056 } This code hasn't changed in a very long time. Looks like KMSAN is confused...