[PATCH net] igb: Fix Null-pointer dereference in igb_reset_q_vector

[PATCH net] igb: Fix Null-pointer dereference in igb_reset_q_vector

[Christoph Paasch]

When igb_set_interrupt_capability() calls
igb_reset_interrupt_capability() (e.g., because CONFIG_PCI_MSI is unset),
num_q_vectors has been set but no vector has yet been allocated.

igb_reset_interrupt_capability() will then call igb_reset_q_vector,
which assumes that the vector is allocated. As this is not the case, we
are accessing a NULL-pointer.

This patch fixes it by checking that q_vector is indeed different from
NULL.

Fixes: 02ef6e1d0b0023 (igb: Fix queue allocation method to accommodate changing during runtime)
Cc: Carolyn Wyborny <carolyn.wyborny@intel.com>
Signed-off-by: Christoph Paasch <christoph.paasch@uclouvain.be>
---
 drivers/net/ethernet/intel/igb/igb_main.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/drivers/net/ethernet/intel/igb/igb_main.c b/drivers/net/ethernet/intel/igb/igb_main.c
index 46d31a49f5ea..bfcf192ee87d 100644
--- a/drivers/net/ethernet/intel/igb/igb_main.c
+++ b/drivers/net/ethernet/intel/igb/igb_main.c
@@ -1014,6 +1014,12 @@ static void igb_reset_q_vector(struct igb_adapter *adapter, int v_idx)
 {
 	struct igb_q_vector *q_vector = adapter->q_vector[v_idx];
 
+	/* Coming from igb_set_interrupt_capability, the vectors are not yet
+	 * allocated. So, q_vector is NULL so we should stop here.
+	 */
+	if (!q_vector)
+		return;
+
 	if (q_vector->tx.ring)
 		adapter->tx_ring[q_vector->tx.ring->queue_index] = NULL;
 
-- 
1.8.3.2

Re: [PATCH net] igb: Fix Null-pointer dereference in igb_reset_q_vector

[David Miller]

From: Christoph Paasch <christoph.paasch@uclouvain.be>
Date: Tue, 18 Feb 2014 14:06:57 +0100

> When igb_set_interrupt_capability() calls
> igb_reset_interrupt_capability() (e.g., because CONFIG_PCI_MSI is unset),
> num_q_vectors has been set but no vector has yet been allocated.
> 
> igb_reset_interrupt_capability() will then call igb_reset_q_vector,
> which assumes that the vector is allocated. As this is not the case, we
> are accessing a NULL-pointer.
> 
> This patch fixes it by checking that q_vector is indeed different from
> NULL.
> 
> Fixes: 02ef6e1d0b0023 (igb: Fix queue allocation method to accommodate changing during runtime)
> Cc: Carolyn Wyborny <carolyn.wyborny@intel.com>
> Signed-off-by: Christoph Paasch <christoph.paasch@uclouvain.be>

Intel folks, please queue this up, thanks.

Re: [PATCH net] igb: Fix Null-pointer dereference in igb_reset_q_vector

[Brown, Aaron F]

On Tue, 2014-02-18 at 14:06 +0100, Christoph Paasch wrote:
> When igb_set_interrupt_capability() calls
> igb_reset_interrupt_capability() (e.g., because CONFIG_PCI_MSI is unset),
> num_q_vectors has been set but no vector has yet been allocated.
> 
> igb_reset_interrupt_capability() will then call igb_reset_q_vector,
> which assumes that the vector is allocated. As this is not the case, we
> are accessing a NULL-pointer.
> 
> This patch fixes it by checking that q_vector is indeed different from
> NULL.
> 
> Fixes: 02ef6e1d0b0023 (igb: Fix queue allocation method to accommodate changing during runtime)
> Cc: Carolyn Wyborny <carolyn.wyborny@intel.com>
> Signed-off-by: Christoph Paasch <christoph.paasch@uclouvain.be>
> ---
>  drivers/net/ethernet/intel/igb/igb_main.c | 6 ++++++
>  1 file changed, 6 insertions(+)

Thanks Christoph, I have added this to our Jeff's internal queue.