diff mbox series

net: check that seg is valid before dereference

Message ID 20200928153219.285343-1-3chas3@gmail.com (mailing list archive)
State Superseded, archived
Delegated to: Thomas Monjalon
Headers
Series net: check that seg is valid before dereference |

Checks

Context Check Description
ci/checkpatch success coding style OK
ci/iol-broadcom-Functional success Functional Testing PASS
ci/iol-intel-Functional success Functional Testing PASS
ci/iol-broadcom-Performance success Performance Testing PASS
ci/iol-testing success Testing PASS
ci/Intel-compilation success Compilation OK
ci/iol-intel-Performance success Performance Testing PASS
ci/travis-robot success Travis build: passed
ci/iol-mellanox-Performance success Performance Testing PASS

Commit Message

Chas Williams Sept. 28, 2020, 3:32 p.m. UTC 
  If the overall pkt_len and segment lengths are out of agreement,
it is possible for the seg to be NULL after the loop. Add assert
to check this condition in debug builds.

Fixes: c442fed81bb9 ("net: add function to calculate checksum in mbuf")

Signed-off-by: Chas Williams <3chas3@gmail.com>
---
 lib/librte_net/rte_ip.h | 1 +
 1 file changed, 1 insertion(+)

Comments

Yunjian Wang Sept. 29, 2020, 3:01 a.m. UTC | #1 
> -----Original Message-----
> From: dev [mailto:dev-bounces@dpdk.org] On Behalf Of Chas Williams
> Sent: Monday, September 28, 2020 11:32 PM
> To: dev@dpdk.org
> Cc: olivier.matz@6wind.com; Chas Williams <3chas3@gmail.com>
> Subject: [dpdk-dev] [PATCH] net: check that seg is valid before dereference
> 
> If the overall pkt_len and segment lengths are out of agreement, it is possible
> for the seg to be NULL after the loop. Add assert to check this condition in
> debug builds.
> 
> Fixes: c442fed81bb9 ("net: add function to calculate checksum in mbuf")
> 
> Signed-off-by: Chas Williams <3chas3@gmail.com>
> ---
>  lib/librte_net/rte_ip.h | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/lib/librte_net/rte_ip.h b/lib/librte_net/rte_ip.h index
> fcd1eb342..6b3e4cdda 100644
> --- a/lib/librte_net/rte_ip.h
> +++ b/lib/librte_net/rte_ip.h
> @@ -225,6 +225,7 @@ rte_raw_cksum_mbuf(const struct rte_mbuf *m,
> uint32_t off, uint32_t len,
>  			break;
>  		off -= seglen;
>  	}
> +	RTE_ASSERT(seg != NULL);

Is it better to return an error code?

>  	seglen -= off;
>  	buf = rte_pktmbuf_mtod_offset(seg, const char *, off);
>  	if (seglen >= len) {
> --
> 2.26.2
Chas Williams Sept. 29, 2020, 8:19 p.m. UTC | #2 
On 9/28/20 11:01 PM, wangyunjian wrote:
>> -----Original Message-----
>> From: dev [mailto:dev-bounces@dpdk.org] On Behalf Of Chas Williams
>> Sent: Monday, September 28, 2020 11:32 PM
>> To: dev@dpdk.org
>> Cc: olivier.matz@6wind.com; Chas Williams <3chas3@gmail.com>
>> Subject: [dpdk-dev] [PATCH] net: check that seg is valid before dereference
>>
>> If the overall pkt_len and segment lengths are out of agreement, it is possible
>> for the seg to be NULL after the loop. Add assert to check this condition in
>> debug builds.
>>
>> Fixes: c442fed81bb9 ("net: add function to calculate checksum in mbuf")
>>
>> Signed-off-by: Chas Williams <3chas3@gmail.com>
>> ---
>>   lib/librte_net/rte_ip.h | 1 +
>>   1 file changed, 1 insertion(+)
>>
>> diff --git a/lib/librte_net/rte_ip.h b/lib/librte_net/rte_ip.h index
>> fcd1eb342..6b3e4cdda 100644
>> --- a/lib/librte_net/rte_ip.h
>> +++ b/lib/librte_net/rte_ip.h
>> @@ -225,6 +225,7 @@ rte_raw_cksum_mbuf(const struct rte_mbuf *m,
>> uint32_t off, uint32_t len,
>>                      break;
>>              off -= seglen;
>>      }
>> +    RTE_ASSERT(seg != NULL);
>
> Is it better to return an error code?

Maybe. However, to get into this state your mbuf chain is already badly broken.
Personally, I would prefer an immediate failure in the application so
I can track
down the source of this error.

No one is checking the return code now, so returning one wouldn't
really help unless I also fix the callers. Lastly, would everyone
be happy with an extra branch in the virtio RX path?


>
>>      seglen -= off;
>>      buf = rte_pktmbuf_mtod_offset(seg, const char *, off);
>>      if (seglen >= len) {
>> --
>> 2.26.2
>
diff mbox series

Patch

diff --git a/lib/librte_net/rte_ip.h b/lib/librte_net/rte_ip.h
index fcd1eb342..6b3e4cdda 100644
--- a/lib/librte_net/rte_ip.h
+++ b/lib/librte_net/rte_ip.h
@@ -225,6 +225,7 @@  rte_raw_cksum_mbuf(const struct rte_mbuf *m, uint32_t off, uint32_t len,
 			break;
 		off -= seglen;
 	}
+	RTE_ASSERT(seg != NULL);
 	seglen -= off;
 	buf = rte_pktmbuf_mtod_offset(seg, const char *, off);
 	if (seglen >= len) {