[PATCH RESEND] ptp: Fixes a null pointer dereference in ptp_ioctl

[PATCH RESEND] ptp: Fixes a null pointer dereference in ptp_ioctl

[Yuran Pereira]

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: c5a445b1e934 ("ptp: support event queue reader channel masks")
Signed-off-by: Yuran Pereira <yuran.pereira@hotmail.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) {
 
-- 
2.25.1

Re: [PATCH RESEND] ptp: Fixes a null pointer dereference in ptp_ioctl

[Przemek Kitszel]

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@syzkaller.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@hotmail.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@intel.com>

Re: [PATCH RESEND] ptp: Fixes a null pointer dereference in ptp_ioctl

[Przemek Kitszel]

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@syzkaller.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@hotmail.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@intel.com>
> 

Still applies, code is fine, thanks!

Re: [PATCH RESEND] ptp: Fixes a null pointer dereference in ptp_ioctl

[patchwork-bot+netdevbpf]

Hello:

This patch was applied to netdev/net.git (main)
by David S. Miller <davem@davemloft.net>:

On Wed,  8 Nov 2023 02:18:36 +0530 you 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
> ```
> 
> [...]

Here is the summary with links:
  - [RESEND] ptp: Fixes a null pointer dereference in ptp_ioctl
    https://git.kernel.org/netdev/net/c/8a4f030dbced

You are awesome, thank you!
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