From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jeff Kirsher Subject: [net-next v2 06/15] fm10k: prevent null pointer dereference of msix_entries table Date: Tue, 5 Apr 2016 13:02:18 -0700 Message-ID: <1459886547-146445-7-git-send-email-jeffrey.t.kirsher@intel.com> References: <1459886547-146445-1-git-send-email-jeffrey.t.kirsher@intel.com> Cc: Jacob Keller , netdev@vger.kernel.org, nhorman@redhat.com, sassmann@redhat.com, jogreene@redhat.com, Jeff Kirsher To: davem@davemloft.net Return-path: Received: from mga09.intel.com ([134.134.136.24]:56328 "EHLO mga09.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759865AbcDEUCb (ORCPT ); Tue, 5 Apr 2016 16:02:31 -0400 In-Reply-To: <1459886547-146445-1-git-send-email-jeffrey.t.kirsher@intel.com> Sender: netdev-owner@vger.kernel.org List-ID: From: Jacob Keller According to the C standard dereferencing a variable before it is checked invokes undefined behavior, and thus compilers are free to assume the check for NULL isn't necessary. Prevent this by re-ordering the NULL check of msix_entries in fm10k_free_mbx_irq. Signed-off-by: Jacob Keller Tested-by: Krishneil Singh Signed-off-by: Jeff Kirsher --- drivers/net/ethernet/intel/fm10k/fm10k_pci.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/drivers/net/ethernet/intel/fm10k/fm10k_pci.c b/drivers/net/ethernet/intel/fm10k/fm10k_pci.c index 6190a81..8c23fb3d 100644 --- a/drivers/net/ethernet/intel/fm10k/fm10k_pci.c +++ b/drivers/net/ethernet/intel/fm10k/fm10k_pci.c @@ -1143,14 +1143,16 @@ static irqreturn_t fm10k_msix_mbx_pf(int __always_unused irq, void *data) void fm10k_mbx_free_irq(struct fm10k_intfc *interface) { - struct msix_entry *entry = &interface->msix_entries[FM10K_MBX_VECTOR]; struct fm10k_hw *hw = &interface->hw; + struct msix_entry *entry; int itr_reg; /* no mailbox IRQ to free if MSI-X is not enabled */ if (!interface->msix_entries) return; + entry = &interface->msix_entries[FM10K_MBX_VECTOR]; + /* disconnect the mailbox */ hw->mbx.ops.disconnect(hw, &hw->mbx); -- 2.5.5