[dpdk-dev] [PATCH] net/softnic: fix memory illegal access

[dpdk-dev] [PATCH] net/softnic: fix memory illegal access

[Jasvinder Singh]

While deleting the elements from the linked list, TAILQ_FOREACH causes
read from the freed pointer. Fixes the issue by using for loop instead
of TAILQ_FOREACH.

Coverity issue: 302867
Fixes: bef50bcb1c47 ("net/softnic: implement start and stop")

Signed-off-by: Jasvinder Singh <jasvinder.singh@intel.com>
Acked-by: Cristian Dumitrescu <cristian.dumitrescu@intel.com>
---
 drivers/net/softnic/rte_eth_softnic_swq.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/net/softnic/rte_eth_softnic_swq.c b/drivers/net/softnic/rte_eth_softnic_swq.c
index 1944fbb..a1f1899 100644
--- a/drivers/net/softnic/rte_eth_softnic_swq.c
+++ b/drivers/net/softnic/rte_eth_softnic_swq.c
@@ -36,9 +36,11 @@ softnic_swq_free(struct pmd_internals *p)
 void
 softnic_softnic_swq_free_keep_rxq_txq(struct pmd_internals *p)
 {
-	struct softnic_swq *swq;
+	struct softnic_swq *swq, *swq_next;
+
+	for (swq = TAILQ_FIRST(&p->swq_list); swq != NULL; swq = swq_next) {
+		swq_next = TAILQ_NEXT(swq, node);
 
-	TAILQ_FOREACH(swq, &p->swq_list, node) {
 		if ((strncmp(swq->name, "RXQ", strlen("RXQ")) == 0) ||
 			(strncmp(swq->name, "TXQ", strlen("TXQ")) == 0))
 			continue;
-- 
2.9.3

Re: [dpdk-dev] [PATCH] net/softnic: fix memory illegal access

[Bruce Richardson]

On Fri, Jul 20, 2018 at 10:44:39AM +0100, Jasvinder Singh wrote:
> While deleting the elements from the linked list, TAILQ_FOREACH causes
> read from the freed pointer. Fixes the issue by using for loop instead
> of TAILQ_FOREACH.
> 
> Coverity issue: 302867
> Fixes: bef50bcb1c47 ("net/softnic: implement start and stop")
> 
> Signed-off-by: Jasvinder Singh <jasvinder.singh@intel.com>
> Acked-by: Cristian Dumitrescu <cristian.dumitrescu@intel.com>
> ---
>  drivers/net/softnic/rte_eth_softnic_swq.c | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/net/softnic/rte_eth_softnic_swq.c b/drivers/net/softnic/rte_eth_softnic_swq.c
> index 1944fbb..a1f1899 100644
> --- a/drivers/net/softnic/rte_eth_softnic_swq.c
> +++ b/drivers/net/softnic/rte_eth_softnic_swq.c
> @@ -36,9 +36,11 @@ softnic_swq_free(struct pmd_internals *p)
>  void
>  softnic_softnic_swq_free_keep_rxq_txq(struct pmd_internals *p)
>  {
> -	struct softnic_swq *swq;
> +	struct softnic_swq *swq, *swq_next;
> +
> +	for (swq = TAILQ_FIRST(&p->swq_list); swq != NULL; swq = swq_next) {
> +		swq_next = TAILQ_NEXT(swq, node);
>  
> -	TAILQ_FOREACH(swq, &p->swq_list, node) {
>  		if ((strncmp(swq->name, "RXQ", strlen("RXQ")) == 0) ||
>  			(strncmp(swq->name, "TXQ", strlen("TXQ")) == 0))

TAILQ_FOREACH_SAFE is probably what you want to use here.

>From man page:

     The macros TAILQ_FOREACH, TAILQ_FOREACH_REVERSE, TAILQ_FOREACH_SAFE, and
     TAILQ_FOREACH_REVERSE_SAFE traverse the tail queue referenced by head in
     the forward or reverse direction direction, assigning each element in
     turn to var.

     The SAFE versions use tmp to hold the next element, so var may be freed
     or removed from the list.

Re: [dpdk-dev] [PATCH] net/softnic: fix memory illegal access

[Van Haaren, Harry]

> -----Original Message-----
> From: dev [mailto:dev-bounces@dpdk.org] On Behalf Of Jasvinder Singh
> Sent: Friday, July 20, 2018 10:45 AM
> To: dev@dpdk.org
> Cc: Dumitrescu, Cristian <cristian.dumitrescu@intel.com>
> Subject: [dpdk-dev] [PATCH] net/softnic: fix memory illegal access
> 
> While deleting the elements from the linked list, TAILQ_FOREACH causes
> read from the freed pointer. Fixes the issue by using for loop instead
> of TAILQ_FOREACH.
> 
> Coverity issue: 302867
> Fixes: bef50bcb1c47 ("net/softnic: implement start and stop")
> 
> Signed-off-by: Jasvinder Singh <jasvinder.singh@intel.com>
> Acked-by: Cristian Dumitrescu <cristian.dumitrescu@intel.com>
> ---
>  drivers/net/softnic/rte_eth_softnic_swq.c | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/net/softnic/rte_eth_softnic_swq.c
> b/drivers/net/softnic/rte_eth_softnic_swq.c
> index 1944fbb..a1f1899 100644
> --- a/drivers/net/softnic/rte_eth_softnic_swq.c
> +++ b/drivers/net/softnic/rte_eth_softnic_swq.c
> @@ -36,9 +36,11 @@ softnic_swq_free(struct pmd_internals *p)
>  void
>  softnic_softnic_swq_free_keep_rxq_txq(struct pmd_internals *p)
>  {
> -	struct softnic_swq *swq;
> +	struct softnic_swq *swq, *swq_next;
> +
> +	for (swq = TAILQ_FIRST(&p->swq_list); swq != NULL; swq = swq_next) {
> +		swq_next = TAILQ_NEXT(swq, node);
> 
> -	TAILQ_FOREACH(swq, &p->swq_list, node) {
>  		if ((strncmp(swq->name, "RXQ", strlen("RXQ")) == 0) ||
>  			(strncmp(swq->name, "TXQ", strlen("TXQ")) == 0))
>  			continue;


The TAILQ_FOREACH_SAFE() macro handles exactly this case. Although it is not
in the linux TAILQ header, DPDK provides it in rte_tailq.h:

http://git.dpdk.org/dpdk/tree/lib/librte_eal/common/include/rte_tailq.h#n130

I think it is cleaner to use the MACRO instead of manually doing the loop,
linked-list iter + delete is error prone enough already :)

Re: [dpdk-dev] [PATCH] net/softnic: fix memory illegal access

[Singh, Jasvinder]

> -----Original Message-----
> From: Van Haaren, Harry
> Sent: Friday, July 20, 2018 11:32 AM
> To: Singh, Jasvinder <jasvinder.singh@intel.com>; dev@dpdk.org
> Cc: Dumitrescu, Cristian <cristian.dumitrescu@intel.com>
> Subject: RE: [dpdk-dev] [PATCH] net/softnic: fix memory illegal access
> 
> > -----Original Message-----
> > From: dev [mailto:dev-bounces@dpdk.org] On Behalf Of Jasvinder Singh
> > Sent: Friday, July 20, 2018 10:45 AM
> > To: dev@dpdk.org
> > Cc: Dumitrescu, Cristian <cristian.dumitrescu@intel.com>
> > Subject: [dpdk-dev] [PATCH] net/softnic: fix memory illegal access
> >
> > While deleting the elements from the linked list, TAILQ_FOREACH causes
> > read from the freed pointer. Fixes the issue by using for loop instead
> > of TAILQ_FOREACH.
> >
> > Coverity issue: 302867
> > Fixes: bef50bcb1c47 ("net/softnic: implement start and stop")
> >
> > Signed-off-by: Jasvinder Singh <jasvinder.singh@intel.com>
> > Acked-by: Cristian Dumitrescu <cristian.dumitrescu@intel.com>
> > ---
> >  drivers/net/softnic/rte_eth_softnic_swq.c | 6 ++++--
> >  1 file changed, 4 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/net/softnic/rte_eth_softnic_swq.c
> > b/drivers/net/softnic/rte_eth_softnic_swq.c
> > index 1944fbb..a1f1899 100644
> > --- a/drivers/net/softnic/rte_eth_softnic_swq.c
> > +++ b/drivers/net/softnic/rte_eth_softnic_swq.c
> > @@ -36,9 +36,11 @@ softnic_swq_free(struct pmd_internals *p)  void
> > softnic_softnic_swq_free_keep_rxq_txq(struct pmd_internals *p)  {
> > -	struct softnic_swq *swq;
> > +	struct softnic_swq *swq, *swq_next;
> > +
> > +	for (swq = TAILQ_FIRST(&p->swq_list); swq != NULL; swq = swq_next) {
> > +		swq_next = TAILQ_NEXT(swq, node);
> >
> > -	TAILQ_FOREACH(swq, &p->swq_list, node) {
> >  		if ((strncmp(swq->name, "RXQ", strlen("RXQ")) == 0) ||
> >  			(strncmp(swq->name, "TXQ", strlen("TXQ")) == 0))
> >  			continue;
> 
> 
> The TAILQ_FOREACH_SAFE() macro handles exactly this case. Although it is not
> in the linux TAILQ header, DPDK provides it in rte_tailq.h:
> 
> http://git.dpdk.org/dpdk/tree/lib/librte_eal/common/include/rte_tailq.h#n13
> 0
> 
> I think it is cleaner to use the MACRO instead of manually doing the loop,
> linked-list iter + delete is error prone enough already :)

Macro lessens the confusion as well  :)  thanks, Harry!

[dpdk-dev] [PATCH v2] net/softnic: fix memory illegal access

[Jasvinder Singh]

While deleting the elements from the linked list, TAILQ_FOREACH causes
read from the freed pointer. Fixes the issue by using TAILQ_FOREACH_SAFE
instead.

Coverity issue: 302867
Fixes: bef50bcb1c47 ("net/softnic: implement start and stop")

Signed-off-by: Jasvinder Singh <jasvinder.singh@intel.com>
Acked-by: Cristian Dumitrescu <cristian.dumitrescu@intel.com>
---
 drivers/net/softnic/rte_eth_softnic_swq.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/net/softnic/rte_eth_softnic_swq.c b/drivers/net/softnic/rte_eth_softnic_swq.c
index 1944fbb..2083d0a 100644
--- a/drivers/net/softnic/rte_eth_softnic_swq.c
+++ b/drivers/net/softnic/rte_eth_softnic_swq.c
@@ -6,6 +6,7 @@
 #include <string.h>
 
 #include <rte_string_fns.h>
+#include <rte_tailq.h>
 
 #include "rte_eth_softnic_internals.h"
 
@@ -36,9 +37,9 @@ softnic_swq_free(struct pmd_internals *p)
 void
 softnic_softnic_swq_free_keep_rxq_txq(struct pmd_internals *p)
 {
-	struct softnic_swq *swq;
+	struct softnic_swq *swq, *tswq;
 
-	TAILQ_FOREACH(swq, &p->swq_list, node) {
+	TAILQ_FOREACH_SAFE(swq, &p->swq_list, node, tswq) {
 		if ((strncmp(swq->name, "RXQ", strlen("RXQ")) == 0) ||
 			(strncmp(swq->name, "TXQ", strlen("TXQ")) == 0))
 			continue;
-- 
2.9.3

Re: [dpdk-dev] [PATCH v2] net/softnic: fix memory illegal access

[Ferruh Yigit]

On 7/20/2018 12:05 PM, Jasvinder Singh wrote:
> While deleting the elements from the linked list, TAILQ_FOREACH causes
> read from the freed pointer. Fixes the issue by using TAILQ_FOREACH_SAFE
> instead.
> 
> Coverity issue: 302867
> Fixes: bef50bcb1c47 ("net/softnic: implement start and stop")
> 
> Signed-off-by: Jasvinder Singh <jasvinder.singh@intel.com>
> Acked-by: Cristian Dumitrescu <cristian.dumitrescu@intel.com>

Applied to dpdk-next-net/master, thanks.