Re: [PATCH net 2/2] gve: fix NULL dereference due to missing ptp adjfine

[Vadim Fedorenko <vadim.fedorenko@linux.dev>]

On 07/08/2026 23:43, Harshitha Ramamurthy wrote:
> From: Jordan Rhee <jordanrhee@google.com>
> 
> Fix NULL dereference due to missing implementation of adjfine, which can
> be triggered from usermode as follows:
> 
> sudo ./testptp -d /dev/ptp0 -f 0
> [  551.943697] BUG: kernel NULL pointer dereference, address: 0000000000000000
> [...]
> [  552.061946] Call Trace:
> [  552.064487]  <TASK>
> [  552.066681]  ptp_clock_adjtime+0x1c0/0x2c0
> [  552.070874]  ? get_clock_desc+0x6b/0xb0
> [  552.074825]  pc_clock_adjtime+0x78/0xc0
> [  552.078755]  __do_sys_clock_adjtime+0x85/0x110
> [  552.083293]  do_syscall_64+0xea/0x610
> 
> Cc: stable@vger.kernel.org
> Fixes: acd16380523b ("gve: Add initial PTP device support")
> Signed-off-by: Jordan Rhee <jordanrhee@google.com>
> Signed-off-by: Harshitha Ramamurthy <hramamurthy@google.com>
> ---
>   drivers/net/ethernet/google/gve/gve_ptp.c | 6 ++++++
>   1 file changed, 6 insertions(+)
> 
> diff --git a/drivers/net/ethernet/google/gve/gve_ptp.c b/drivers/net/ethernet/google/gve/gve_ptp.c
> index 06b1cf4a5efc..1d6c59f4ead3 100644
> --- a/drivers/net/ethernet/google/gve/gve_ptp.c
> +++ b/drivers/net/ethernet/google/gve/gve_ptp.c
> @@ -26,6 +26,11 @@ int gve_clock_nic_ts_read(struct gve_priv *priv)
>   	return 0;
>   }
>   
> +static int gve_ptp_adjfine(struct ptp_clock_info *ptp, long scaled_ppm)
> +{
> +	return -EOPNOTSUPP;
> +}
> +
>   static int gve_ptp_gettimex64(struct ptp_clock_info *info,
>   			      struct timespec64 *ts,
>   			      struct ptp_system_timestamp *sts)
> @@ -60,6 +65,7 @@ static long gve_ptp_do_aux_work(struct ptp_clock_info *info)
>   static const struct ptp_clock_info gve_ptp_caps = {
>   	.owner          = THIS_MODULE,
>   	.name		= "gve clock",
> +	.adjfine	= gve_ptp_adjfine,
>   	.gettimex64	= gve_ptp_gettimex64,
>   	.settime64	= gve_ptp_settime64,
>   	.do_aux_work	= gve_ptp_do_aux_work,

.adjtime has to be implemented as well - neither adjfine nor adjtime are
checked within ptp_clock_adjtime()