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Message-ID: <5a289765-638a-2a8c-b56d-fc323a69fe2b@intel.com>
Date: Wed, 8 Nov 2023 11:26:02 +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 11/8/23 11:15, Przemek Kitszel wrote:
> On 11/7/23 21:48, Yuran Pereira wrote:
>> Syzkaller found a null pointer dereference in ptp_ioctl
Ugh, I just noticed that this is a fixed version of previous attempt,
for those please always bump version and include changelog, please
also comply with:
https://www.kernel.org/doc/html/next/process/maintainer-netdev.html
if only to don't fool random reviewers
(I somewhat assumed that you have just rebased some old patch,
PATCH RESEND was misleading here)
>> 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>
>
Still applies, code is fine, thanks!
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