Re: [PATCH net 6/8] net/mlx5e: Do not use ptp structure for tx ts stats when not initialized

[Simon Horman <horms@kernel.org>]

On Wed, May 22, 2024 at 10:26:57PM +0300, Tariq Toukan wrote:
> From: Rahul Rameshbabu <rrameshbabu@nvidia.com>
> 
> The ptp channel instance is only initialized when ptp traffic is first
> processed by the driver. This means that there is a window in between when
> port timestamping is enabled and ptp traffic is sent where the ptp channel
> instance is not initialized. Accessing statistics during this window will
> lead to an access violation (NULL + member offset). Check the validity of
> the instance before attempting to query statistics.
> 
>   BUG: unable to handle page fault for address: 0000000000003524
>   #PF: supervisor read access in kernel mode
>   #PF: error_code(0x0000) - not-present page
>   PGD 109dfc067 P4D 109dfc067 PUD 1064ef067 PMD 0
>   Oops: 0000 [#1] SMP
>   CPU: 0 PID: 420 Comm: ethtool Not tainted 6.9.0-rc2-rrameshbabu+ #245
>   Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS Arch Linux 1.16.3-1-1 04/01/204
>   RIP: 0010:mlx5e_stats_ts_get+0x4c/0x130
>   <snip>
>   Call Trace:
>    <TASK>
>    ? show_regs+0x60/0x70
>    ? __die+0x24/0x70
>    ? page_fault_oops+0x15f/0x430
>    ? do_user_addr_fault+0x2c9/0x5c0
>    ? exc_page_fault+0x63/0x110
>    ? asm_exc_page_fault+0x27/0x30
>    ? mlx5e_stats_ts_get+0x4c/0x130
>    ? mlx5e_stats_ts_get+0x20/0x130
>    mlx5e_get_ts_stats+0x15/0x20
>   <snip>
> 
> Fixes: 3579032c08c1 ("net/mlx5e: Implement ethtool hardware timestamping statistics")
> Signed-off-by: Rahul Rameshbabu <rrameshbabu@nvidia.com>
> Signed-off-by: Tariq Toukan <tariqt@nvidia.com>

Reviewed-by: Simon Horman <horms@kernel.org>