[PATCH iwl-next v2] ixgbe: Fix possible skb NULL pointer dereference

[PATCH iwl-next v2] ixgbe: Fix possible skb NULL pointer dereference

[Piotr Kwapulinski]

The commit c824125cbb18 ("ixgbe: Fix passing 0 to ERR_PTR in
ixgbe_run_xdp()") stopped utilizing the ERR-like macros for xdp status
encoding. Propagate this logic to the ixgbe_put_rx_buffer().

The commit also relaxed the skb NULL pointer check - caught by Smatch.
Restore this check.

Fixes: c824125cbb18 ("ixgbe: Fix passing 0 to ERR_PTR in ixgbe_run_xdp()")
Reported-by: Dan Carpenter <dan.carpenter@linaro.org>
Signed-off-by: Piotr Kwapulinski <piotr.kwapulinski@intel.com>
---
 drivers/net/ethernet/intel/ixgbe/ixgbe_main.c | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c b/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
index 7236f20..c682c3d 100644
--- a/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
+++ b/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
@@ -2098,14 +2098,14 @@ static struct ixgbe_rx_buffer *ixgbe_get_rx_buffer(struct ixgbe_ring *rx_ring,
 
 static void ixgbe_put_rx_buffer(struct ixgbe_ring *rx_ring,
 				struct ixgbe_rx_buffer *rx_buffer,
-				struct sk_buff *skb,
-				int rx_buffer_pgcnt)
+				struct sk_buff *skb, int rx_buffer_pgcnt,
+				int xdp_res)
 {
 	if (ixgbe_can_reuse_rx_page(rx_buffer, rx_buffer_pgcnt)) {
 		/* hand second half of page back to the ring */
 		ixgbe_reuse_rx_page(rx_ring, rx_buffer);
 	} else {
-		if (!IS_ERR(skb) && IXGBE_CB(skb)->dma == rx_buffer->dma) {
+		if (skb && !xdp_res && IXGBE_CB(skb)->dma == rx_buffer->dma) {
 			/* the page has been released from the ring */
 			IXGBE_CB(skb)->page_released = true;
 		} else {
@@ -2415,7 +2415,8 @@ static int ixgbe_clean_rx_irq(struct ixgbe_q_vector *q_vector,
 			break;
 		}
 
-		ixgbe_put_rx_buffer(rx_ring, rx_buffer, skb, rx_buffer_pgcnt);
+		ixgbe_put_rx_buffer(rx_ring, rx_buffer, skb, rx_buffer_pgcnt,
+				    xdp_res);
 		cleaned_count++;
 
 		/* place incomplete frames back on ring for completion */
-- 
v1 -> v2
  Provide extra details in commit message for motivation of this patch.

2.43.0

Re: [PATCH iwl-next v2] ixgbe: Fix possible skb NULL pointer dereference

[Maciej Fijalkowski]

On Fri, Jan 17, 2025 at 04:49:35PM +0100, Piotr Kwapulinski wrote:
> The commit c824125cbb18 ("ixgbe: Fix passing 0 to ERR_PTR in
> ixgbe_run_xdp()") stopped utilizing the ERR-like macros for xdp status
> encoding. Propagate this logic to the ixgbe_put_rx_buffer().
> 
> The commit also relaxed the skb NULL pointer check - caught by Smatch.
> Restore this check.
> 
> Fixes: c824125cbb18 ("ixgbe: Fix passing 0 to ERR_PTR in ixgbe_run_xdp()")
> Reported-by: Dan Carpenter <dan.carpenter@linaro.org>
> Signed-off-by: Piotr Kwapulinski <piotr.kwapulinski@intel.com>
> ---
>  drivers/net/ethernet/intel/ixgbe/ixgbe_main.c | 9 +++++----
>  1 file changed, 5 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c b/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
> index 7236f20..c682c3d 100644
> --- a/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
> +++ b/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
> @@ -2098,14 +2098,14 @@ static struct ixgbe_rx_buffer *ixgbe_get_rx_buffer(struct ixgbe_ring *rx_ring,
>  
>  static void ixgbe_put_rx_buffer(struct ixgbe_ring *rx_ring,
>  				struct ixgbe_rx_buffer *rx_buffer,
> -				struct sk_buff *skb,
> -				int rx_buffer_pgcnt)
> +				struct sk_buff *skb, int rx_buffer_pgcnt,
> +				int xdp_res)
>  {
>  	if (ixgbe_can_reuse_rx_page(rx_buffer, rx_buffer_pgcnt)) {
>  		/* hand second half of page back to the ring */
>  		ixgbe_reuse_rx_page(rx_ring, rx_buffer);
>  	} else {
> -		if (!IS_ERR(skb) && IXGBE_CB(skb)->dma == rx_buffer->dma) {
> +		if (skb && !xdp_res && IXGBE_CB(skb)->dma == rx_buffer->dma) {

xdp_res check is redundant here. skb ptr will be non-null only for xdp_res
== 0. so skb != NULL implies xdp_res == 0.

If I am not mistaken:D or ixgbe has some code path I missed.

Besides this, thanks for improving commit message!

>  			/* the page has been released from the ring */
>  			IXGBE_CB(skb)->page_released = true;
>  		} else {
> @@ -2415,7 +2415,8 @@ static int ixgbe_clean_rx_irq(struct ixgbe_q_vector *q_vector,
>  			break;
>  		}
>  
> -		ixgbe_put_rx_buffer(rx_ring, rx_buffer, skb, rx_buffer_pgcnt);
> +		ixgbe_put_rx_buffer(rx_ring, rx_buffer, skb, rx_buffer_pgcnt,
> +				    xdp_res);
>  		cleaned_count++;
>  
>  		/* place incomplete frames back on ring for completion */
> -- 
> v1 -> v2
>   Provide extra details in commit message for motivation of this patch.
> 
> 2.43.0
> 

RE: [PATCH iwl-next v2] ixgbe: Fix possible skb NULL pointer dereference

[Kwapulinski, Piotr]

>-----Original Message-----
>From: Fijalkowski, Maciej <maciej.fijalkowski@intel.com> 
>Sent: Monday, January 20, 2025 3:45 PM
>To: Kwapulinski, Piotr <piotr.kwapulinski@intel.com>
>Cc: intel-wired-lan@lists.osuosl.org; netdev@vger.kernel.org; dan.carpenter@linaro.org; yuehaibing@huawei.com; Kitszel, Przemyslaw <przemyslaw.kitszel@intel.com>
>Subject: Re: [PATCH iwl-next v2] ixgbe: Fix possible skb NULL pointer dereference
>
>On Fri, Jan 17, 2025 at 04:49:35PM +0100, Piotr Kwapulinski wrote:
>> The commit c824125cbb18 ("ixgbe: Fix passing 0 to ERR_PTR in
>> ixgbe_run_xdp()") stopped utilizing the ERR-like macros for xdp status 
>> encoding. Propagate this logic to the ixgbe_put_rx_buffer().
>> 
>> The commit also relaxed the skb NULL pointer check - caught by Smatch.
>> Restore this check.
>> 
>> Fixes: c824125cbb18 ("ixgbe: Fix passing 0 to ERR_PTR in 
>> ixgbe_run_xdp()")
>> Reported-by: Dan Carpenter <dan.carpenter@linaro.org>
>> Signed-off-by: Piotr Kwapulinski <piotr.kwapulinski@intel.com>
>> ---
>>  drivers/net/ethernet/intel/ixgbe/ixgbe_main.c | 9 +++++----
>>  1 file changed, 5 insertions(+), 4 deletions(-)
>> 
>> diff --git a/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c 
>> b/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
>> index 7236f20..c682c3d 100644
>> --- a/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
>> +++ b/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
>> @@ -2098,14 +2098,14 @@ static struct ixgbe_rx_buffer 
>> *ixgbe_get_rx_buffer(struct ixgbe_ring *rx_ring,
>>  
>>  static void ixgbe_put_rx_buffer(struct ixgbe_ring *rx_ring,
>>  				struct ixgbe_rx_buffer *rx_buffer,
>> -				struct sk_buff *skb,
>> -				int rx_buffer_pgcnt)
>> +				struct sk_buff *skb, int rx_buffer_pgcnt,
>> +				int xdp_res)
>>  {
>>  	if (ixgbe_can_reuse_rx_page(rx_buffer, rx_buffer_pgcnt)) {
>>  		/* hand second half of page back to the ring */
>>  		ixgbe_reuse_rx_page(rx_ring, rx_buffer);
>>  	} else {
>> -		if (!IS_ERR(skb) && IXGBE_CB(skb)->dma == rx_buffer->dma) {
>> +		if (skb && !xdp_res && IXGBE_CB(skb)->dma == rx_buffer->dma) {
>
>xdp_res check is redundant here. skb ptr will be non-null only for xdp_res == 0. so skb != NULL implies xdp_res == 0.
That was tempting but eventually the ixgbe_run_xdp() handles the error exclusively. I suggest to leave it as it is.
Thanks,
Piotr

>
>If I am not mistaken:D or ixgbe has some code path I missed.
>
>Besides this, thanks for improving commit message!
>
>>  			/* the page has been released from the ring */
>>  			IXGBE_CB(skb)->page_released = true;
>>  		} else {
>> @@ -2415,7 +2415,8 @@ static int ixgbe_clean_rx_irq(struct ixgbe_q_vector *q_vector,
>>  			break;
>>  		}
>>  
>> -		ixgbe_put_rx_buffer(rx_ring, rx_buffer, skb, rx_buffer_pgcnt);
>> +		ixgbe_put_rx_buffer(rx_ring, rx_buffer, skb, rx_buffer_pgcnt,
>> +				    xdp_res);
>>  		cleaned_count++;
>>  
>>  		/* place incomplete frames back on ring for completion */
>> --
>> v1 -> v2
>>   Provide extra details in commit message for motivation of this patch.
>> 
>> 2.43.0
>>

Re: [PATCH iwl-next v2] ixgbe: Fix possible skb NULL pointer dereference

[Maciej Fijalkowski]

On Thu, Jan 23, 2025 at 09:19:34AM +0100, Kwapulinski, Piotr wrote:
> >-----Original Message-----
> >From: Fijalkowski, Maciej <maciej.fijalkowski@intel.com> 
> >Sent: Monday, January 20, 2025 3:45 PM
> >To: Kwapulinski, Piotr <piotr.kwapulinski@intel.com>
> >Cc: intel-wired-lan@lists.osuosl.org; netdev@vger.kernel.org; dan.carpenter@linaro.org; yuehaibing@huawei.com; Kitszel, Przemyslaw <przemyslaw.kitszel@intel.com>
> >Subject: Re: [PATCH iwl-next v2] ixgbe: Fix possible skb NULL pointer dereference
> >
> >On Fri, Jan 17, 2025 at 04:49:35PM +0100, Piotr Kwapulinski wrote:
> >> The commit c824125cbb18 ("ixgbe: Fix passing 0 to ERR_PTR in
> >> ixgbe_run_xdp()") stopped utilizing the ERR-like macros for xdp status 
> >> encoding. Propagate this logic to the ixgbe_put_rx_buffer().
> >> 
> >> The commit also relaxed the skb NULL pointer check - caught by Smatch.
> >> Restore this check.
> >> 
> >> Fixes: c824125cbb18 ("ixgbe: Fix passing 0 to ERR_PTR in 
> >> ixgbe_run_xdp()")
> >> Reported-by: Dan Carpenter <dan.carpenter@linaro.org>
> >> Signed-off-by: Piotr Kwapulinski <piotr.kwapulinski@intel.com>
> >> ---
> >>  drivers/net/ethernet/intel/ixgbe/ixgbe_main.c | 9 +++++----
> >>  1 file changed, 5 insertions(+), 4 deletions(-)
> >> 
> >> diff --git a/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c 
> >> b/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
> >> index 7236f20..c682c3d 100644
> >> --- a/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
> >> +++ b/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
> >> @@ -2098,14 +2098,14 @@ static struct ixgbe_rx_buffer 
> >> *ixgbe_get_rx_buffer(struct ixgbe_ring *rx_ring,
> >>  
> >>  static void ixgbe_put_rx_buffer(struct ixgbe_ring *rx_ring,
> >>  				struct ixgbe_rx_buffer *rx_buffer,
> >> -				struct sk_buff *skb,
> >> -				int rx_buffer_pgcnt)
> >> +				struct sk_buff *skb, int rx_buffer_pgcnt,
> >> +				int xdp_res)
> >>  {
> >>  	if (ixgbe_can_reuse_rx_page(rx_buffer, rx_buffer_pgcnt)) {
> >>  		/* hand second half of page back to the ring */
> >>  		ixgbe_reuse_rx_page(rx_ring, rx_buffer);
> >>  	} else {
> >> -		if (!IS_ERR(skb) && IXGBE_CB(skb)->dma == rx_buffer->dma) {
> >> +		if (skb && !xdp_res && IXGBE_CB(skb)->dma == rx_buffer->dma) {
> >
> >xdp_res check is redundant here. skb ptr will be non-null only for xdp_res == 0. so skb != NULL implies xdp_res == 0.
> That was tempting but eventually the ixgbe_run_xdp() handles the error exclusively. I suggest to leave it as it is.

ixgbe_run_xdp() on error paths will still return one of our homegrown XDP
statuses:

#define IXGBE_XDP_PASS		0
#define IXGBE_XDP_CONSUMED	BIT(0)
#define IXGBE_XDP_TX		BIT(1)
#define IXGBE_XDP_REDIR		BIT(2)
#define IXGBE_XDP_EXIT		BIT(3)

Plus the case "!xdp_res && !skb" is explicitly checked before calling
ixgbe_put_rx_buffer() and you're gonna break the rx loop altogether. This
happens when you failed to alloc skb for IXGBE_XDP_PASS.

> Thanks,
> Piotr
> 
> >
> >If I am not mistaken:D or ixgbe has some code path I missed.
> >
> >Besides this, thanks for improving commit message!
> >
> >>  			/* the page has been released from the ring */
> >>  			IXGBE_CB(skb)->page_released = true;
> >>  		} else {
> >> @@ -2415,7 +2415,8 @@ static int ixgbe_clean_rx_irq(struct ixgbe_q_vector *q_vector,
> >>  			break;
> >>  		}
> >>  
> >> -		ixgbe_put_rx_buffer(rx_ring, rx_buffer, skb, rx_buffer_pgcnt);
> >> +		ixgbe_put_rx_buffer(rx_ring, rx_buffer, skb, rx_buffer_pgcnt,
> >> +				    xdp_res);
> >>  		cleaned_count++;
> >>  
> >>  		/* place incomplete frames back on ring for completion */
> >> --
> >> v1 -> v2
> >>   Provide extra details in commit message for motivation of this patch.
> >> 
> >> 2.43.0
> >>