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Message-ID: <70911c92-4272-cff6-857e-c95842b644c8@intel.com>
Date: Wed, 8 Nov 2023 11:15:36 +0100
From: Przemek Kitszel <przemyslaw.kitszel@...el.com>
To: Yuran Pereira <yuran.pereira@...mail.com>,
<richardcochran@...il.com>, <netdev@...r.kernel.org>
CC: <eadavis@...com>, <davem@...emloft.net>, <reibax@...il.com>,
<linux-kernel@...r.kernel.org>,
<linux-kernel-mentees@...ts.linuxfoundation.org>,
<syzbot+8a78ecea7ac1a2ea26e5@...kaller.appspotmail.com>
Subject: Re: [PATCH RESEND] ptp: Fixes a null pointer dereference in ptp_ioctl
On 11/7/23 21:48, Yuran Pereira wrote:
> Syzkaller found a null pointer dereference in ptp_ioctl
> originating from the lack of a null check for tsevq.
>
> ```
> general protection fault, probably for non-canonical
> address 0xdffffc000000020b: 0000 [#1] PREEMPT SMP KASAN
> KASAN: probably user-memory-access in range
> [0x0000000000001058-0x000000000000105f]
> CPU: 0 PID: 5053 Comm: syz-executor353 Not tainted
> 6.6.0-syzkaller-10396-g4652b8e4f3ff #0
> Hardware name: Google Google Compute Engine/Google Compute Engine,
> BIOS Google 10/09/2023
> RIP: 0010:ptp_ioctl+0xcb7/0x1d10 drivers/ptp/ptp_chardev.c:476
> ...
> Call Trace:
> <TASK>
> posix_clock_ioctl+0xf8/0x160 kernel/time/posix-clock.c:86
> vfs_ioctl fs/ioctl.c:51 [inline]
> __do_sys_ioctl fs/ioctl.c:871 [inline]
> __se_sys_ioctl fs/ioctl.c:857 [inline]
> __x64_sys_ioctl+0x18f/0x210 fs/ioctl.c:857
> do_syscall_x64 arch/x86/entry/common.c:51 [inline]
> do_syscall_64+0x3f/0x110 arch/x86/entry/common.c:82
> entry_SYSCALL_64_after_hwframe+0x63/0x6b
> ```
>
> This patch fixes the issue by adding a check for tsevq and
> ensuring ptp_ioctl returns with an error if tsevq is null.
>
> Reported-by: syzbot+8a78ecea7ac1a2ea26e5@...kaller.appspotmail.com
> Closes: https://syzkaller.appspot.com/bug?extid=8a78ecea7ac1a2ea26e5
> Fixes: c5a445b1e934 ("ptp: support event queue reader channel masks")
> Signed-off-by: Yuran Pereira <yuran.pereira@...mail.com>
> ---
> drivers/ptp/ptp_chardev.c | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/drivers/ptp/ptp_chardev.c b/drivers/ptp/ptp_chardev.c
> index 282cd7d24077..5b36c34629a0 100644
> --- a/drivers/ptp/ptp_chardev.c
> +++ b/drivers/ptp/ptp_chardev.c
> @@ -173,6 +173,8 @@ long ptp_ioctl(struct posix_clock_context *pccontext, unsigned int cmd,
> int enable, err = 0;
>
> tsevq = pccontext->private_clkdata;
> + if (!tsevq)
> + return -EINVAL;
>
> switch (cmd) {
>
Reviewed-by: Przemek Kitszel <przemyslaw.kitszel@...el.com>
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