2022-11-30 09:00:49

by Yuri Karpov

[permalink] [raw]

Subject: [PATCH] net: dsa: fix NULL pointer dereference in seq_match()

---

ptp_parse_header() result is not checked in seq_match() that can lead
to NULL pointer dereferense.

Found by Linux Verification Center (linuxtesting.org) with SVACE.

Fixes: c6fe0ad2c349 ("net: dsa: mv88e6xxx: add rx/tx timestamping support")
Signed-off-by: Yuri Karpov <[email protected]>
---
drivers/net/dsa/mv88e6xxx/hwtstamp.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/dsa/mv88e6xxx/hwtstamp.c b/drivers/net/dsa/mv88e6xxx/hwtstamp.c
index 331b4ca089ff..97f30795a2bb 100644
--- a/drivers/net/dsa/mv88e6xxx/hwtstamp.c
+++ b/drivers/net/dsa/mv88e6xxx/hwtstamp.c
@@ -246,7 +246,7 @@ static int seq_match(struct sk_buff *skb, u16 ts_seqid)

hdr = ptp_parse_header(skb, type);

- return ts_seqid == ntohs(hdr->sequence_id);
+ return hdr ? ts_seqid == ntohs(hdr->sequence_id) : 0;
}

static void mv88e6xxx_get_rxts(struct mv88e6xxx_chip *chip,
--
2.34.1

2022-11-30 10:43:31

by Pavan Chebbi

[permalink] [raw]

Subject: Re: [PATCH] net: dsa: fix NULL pointer dereference in seq_match()

---

On Wed, Nov 30, 2022 at 2:15 PM Yuri Karpov <[email protected]> wrote:
>
> ptp_parse_header() result is not checked in seq_match() that can lead
> to NULL pointer dereferense.
>
> Found by Linux Verification Center (linuxtesting.org) with SVACE.
>
> Fixes: c6fe0ad2c349 ("net: dsa: mv88e6xxx: add rx/tx timestamping support")
> Signed-off-by: Yuri Karpov <[email protected]>
> ---
> drivers/net/dsa/mv88e6xxx/hwtstamp.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/net/dsa/mv88e6xxx/hwtstamp.c b/drivers/net/dsa/mv88e6xxx/hwtstamp.c
> index 331b4ca089ff..97f30795a2bb 100644
> --- a/drivers/net/dsa/mv88e6xxx/hwtstamp.c
> +++ b/drivers/net/dsa/mv88e6xxx/hwtstamp.c
> @@ -246,7 +246,7 @@ static int seq_match(struct sk_buff *skb, u16 ts_seqid)
>
> hdr = ptp_parse_header(skb, type);
>
> - return ts_seqid == ntohs(hdr->sequence_id);
> + return hdr ? ts_seqid == ntohs(hdr->sequence_id) : 0;
> }

You need to have the target tree in the subject. But change looks good to me.

Reviewed-by: Pavan Chebbi <[email protected]>

>
> static void mv88e6xxx_get_rxts(struct mv88e6xxx_chip *chip,
> --
> 2.34.1
>

---

Attachments:

smime.p7s (4.11 kB)
S/MIME Cryptographic Signature

2022-11-30 22:56:35

by Vladimir Oltean

[permalink] [raw]

Subject: Re: [PATCH] net: dsa: fix NULL pointer dereference in seq_match()

---

On Wed, Nov 30, 2022 at 11:44:31AM +0300, Yuri Karpov wrote:
> ptp_parse_header() result is not checked in seq_match() that can lead
> to NULL pointer dereferense.
>
> Found by Linux Verification Center (linuxtesting.org) with SVACE.
>
> Fixes: c6fe0ad2c349 ("net: dsa: mv88e6xxx: add rx/tx timestamping support")
> Signed-off-by: Yuri Karpov <[email protected]>
> ---
> drivers/net/dsa/mv88e6xxx/hwtstamp.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/net/dsa/mv88e6xxx/hwtstamp.c b/drivers/net/dsa/mv88e6xxx/hwtstamp.c
> index 331b4ca089ff..97f30795a2bb 100644
> --- a/drivers/net/dsa/mv88e6xxx/hwtstamp.c
> +++ b/drivers/net/dsa/mv88e6xxx/hwtstamp.c
> @@ -246,7 +246,7 @@ static int seq_match(struct sk_buff *skb, u16 ts_seqid)
>
> hdr = ptp_parse_header(skb, type);
>
> - return ts_seqid == ntohs(hdr->sequence_id);
> + return hdr ? ts_seqid == ntohs(hdr->sequence_id) : 0;

NACK.

ptp_parse_header() will never return NULL when called from seq_match().
The skb comes from mv88e6xxx_get_rxts(), which takes it from ps->rx_queue.
It was put there by mv88e6xxx_port_rxtstamp(), which prior to that, had
a check for ptp_parse_header() returning NULL in mv88e6xxx_should_tstamp().

Please don't just blindly trust your tools.

> }
>
> static void mv88e6xxx_get_rxts(struct mv88e6xxx_chip *chip,
> --
> 2.34.1
>