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

[Harshitha Ramamurthy <hramamurthy@google.com>]

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,
-- 
2.55.0.679.g6767b8d81c-goog