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>

diff --git a/drivers/net/ethernet/intel/i40e/i40e_common.c b/drivers/net/ethernet/intel/i40e/i40e_common.c
index 5c36a18a31be9a0382184945ed4cbf123bea04d0..111426ba5fbcef4d856efeed10dec6ee34e95ed1 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 d69c2e44cd1a125890871465c72b00e4b7ea9d36..8d3a2bfe186af812115f9973598d0ac75cc4dc69 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,