i40e: prevent snprintf format specifier truncation

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. Additionally, lets
use sizeof(prefix) in order to ensure we use the correct size if we need
to change the array length in the future.

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>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Orabug: 26785018
(cherry picked from commit b5d5504aa1e961fc1f87ee7b092bf5ce1a7bf0de)
Signed-off-by: Jack Vogel <jack.vogel@oracle.com>
Reviewed-by: Kyle Fortin <kyle.fortin@oracle.com>

diff --git a/drivers/net/ethernet/intel/i40e/i40e_common.c b/drivers/net/ethernet/intel/i40e/i40e_common.c
index c052c913a2541a7a055d52c479eeda8204679144..5e053b948a9025281fb0b69489af7ab734facab3 100644 (file)
--- 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, sizeof(prefix),
                                 "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 bcaf4a690403f415e7719f131dd3485ccbeff9f6..0a9a54b5515c688784771dbb670ca7e77cb75dbe 100644 (file)
--- 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, sizeof(prefix),
                                 "i40evf %02x:%02x.%x: \t0x",
                                 hw->bus.bus_id,
                                 hw->bus.device,