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8a4f030dbc
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@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=8a78ecea7ac1a2ea26e5
Fixes: c5a445b1e9 ("ptp: support event queue reader channel masks")
Signed-off-by: Yuran Pereira <yuran.pereira@hotmail.com>
Reviewed-by: Przemek Kitszel <przemyslaw.kitszel@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.