[Intel-wired-lan] [next PATCH S75-V2 06/12] i40e: prevent snprintf format specifier truncation

[Alice Michael <alice.michael@intel.com>]

From: Jacob Keller <jacob.e.keller@intel.com>

Increase the size of the prefix buffer so that it can hold enough
characters for every possible input. Although 20 is enough for all
expected inputs, it is possible for the values to be larger than
expected, resulting in a possibly truncated string.

New versions of GCC starting at 7 now include warnings to prevent
truncation unless you handle the return code. At most 27 bytes can be
written here, so lets just increase the buffer size even if for all
expected hw->bus.* values we only needed 20.

Signed-off-by: Jacob Keller <jacob.e.keller@intel.com>
---
 drivers/net/ethernet/intel/i40e/i40e_common.c   | 4 ++--
 drivers/net/ethernet/intel/i40evf/i40e_common.c | 4 ++--
 2 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/net/ethernet/intel/i40e/i40e_common.c b/drivers/net/ethernet/intel/i40e/i40e_common.c
index 5c36a18..69d5cd8 100644
--- a/drivers/net/ethernet/intel/i40e/i40e_common.c
+++ b/drivers/net/ethernet/intel/i40e/i40e_common.c
@@ -328,9 +328,9 @@ void i40e_debug_aq(struct i40e_hw *hw, enum i40e_debug_mask mask, void *desc,
 			len = buf_len;
 		/* write the full 16-byte chunks */
 		if (hw->debug_mask & mask) {
-			char prefix[20];
+			char prefix[27];
 
-			snprintf(prefix, 20,
+			snprintf(prefix, 27,
 				 "i40e %02x:%02x.%x: \t0x",
 				 hw->bus.bus_id,
 				 hw->bus.device,
diff --git a/drivers/net/ethernet/intel/i40evf/i40e_common.c b/drivers/net/ethernet/intel/i40evf/i40e_common.c
index 1dd1938..d0fc662 100644
--- a/drivers/net/ethernet/intel/i40evf/i40e_common.c
+++ b/drivers/net/ethernet/intel/i40evf/i40e_common.c
@@ -333,9 +333,9 @@ void i40evf_debug_aq(struct i40e_hw *hw, enum i40e_debug_mask mask, void *desc,
 			len = buf_len;
 		/* write the full 16-byte chunks */
 		if (hw->debug_mask & mask) {
-			char prefix[20];
+			char prefix[27];
 
-			snprintf(prefix, 20,
+			snprintf(prefix, 27,
 				 "i40evf %02x:%02x.%x: \t0x",
 				 hw->bus.bus_id,
 				 hw->bus.device,
-- 
2.9.3