[PATCH] net: fec: ptp: fix NULL pointer dereference if ptp_clock is not set

[Philipp Zabel]

Since commit 278d24047891 (net: fec: ptp: Enable PPS output based on ptp clock)
fec_enet_interrupt calls fec_ptp_check_pps_event unconditionally, which calls
into ptp_clock_event. If fep->ptp_clock is NULL, ptp_clock_event tries to
dereference the NULL pointer.
Since on i.MX53 fep->bufdesc_ex is not set, fec_ptp_init is never called,
and fep->ptp_clock is NULL, which reliably causes a kernel panic.

This patch adds a check for fep->ptp_clock == NULL in fec_enet_interrupt.

Signed-off-by: Philipp Zabel <***@pengutronix.de>
---
drivers/net/ethernet/freescale/fec_main.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/freescale/fec_main.c b/drivers/net/ethernet/freescale/fec_main.c
index 81b96cf..50a851d 100644
--- a/drivers/net/ethernet/freescale/fec_main.c
+++ b/drivers/net/ethernet/freescale/fec_main.c
@@ -1581,7 +1581,8 @@ fec_enet_interrupt(int irq, void *dev_id)
complete(&fep->mdio_done);
}

- fec_ptp_check_pps_event(fep);
+ if (fep->ptp_clock)
+ fec_ptp_check_pps_event(fep);

return ret;
}

[David Miller]

From: Philipp Zabel <***@pengutronix.de>
Date: Wed, 22 Oct 2014 16:34:35 +0200

Post by Philipp Zabel
Since commit 278d24047891 (net: fec: ptp: Enable PPS output based on ptp clock)
fec_enet_interrupt calls fec_ptp_check_pps_event unconditionally, which calls
into ptp_clock_event. If fep->ptp_clock is NULL, ptp_clock_event tries to
dereference the NULL pointer.
Since on i.MX53 fep->bufdesc_ex is not set, fec_ptp_init is never called,
and fep->ptp_clock is NULL, which reliably causes a kernel panic.
This patch adds a check for fep->ptp_clock == NULL in fec_enet_interrupt.

Applied, thank you.