net/mlx5e: Correct snprintf truncation handling for fw_version buffer

snprintf returns the length of the formatted string, excluding the trailing
null, without accounting for truncation. This means that is the return
value is greater than or equal to the size parameter, the fw_version string
was truncated.

Reported-by: David Laight <David.Laight@ACULAB.COM>
Closes: https://lore.kernel.org/netdev/81cae734ee1b4cde9b380a9a31006c1a@AcuMS.aculab.com/
Link: https://docs.kernel.org/core-api/kernel-api.html#c.snprintf
Fixes: 41e63c2baa11 ("net/mlx5e: Check return value of snprintf writing to fw_version buffer")
Signed-off-by: Rahul Rameshbabu <rrameshbabu@nvidia.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>

diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en_ethtool.c b/drivers/net/ethernet/mellanox/mlx5/core/en_ethtool.c
index 792a0ea544cd39997378ff43cf61776cb0c69bdd..c7c1b667b105a082148b5d8e99bcf3dde042475d 100644 (file)
--- a/drivers/net/ethernet/mellanox/mlx5/core/en_ethtool.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/en_ethtool.c
@@ -49,7 +49,7 @@ void mlx5e_ethtool_get_drvinfo(struct mlx5e_priv *priv,
        count = snprintf(drvinfo->fw_version, sizeof(drvinfo->fw_version),
                         "%d.%d.%04d (%.16s)", fw_rev_maj(mdev),
                         fw_rev_min(mdev), fw_rev_sub(mdev), mdev->board_id);
-       if (count == sizeof(drvinfo->fw_version))
+       if (count >= sizeof(drvinfo->fw_version))
                snprintf(drvinfo->fw_version, sizeof(drvinfo->fw_version),
                         "%d.%d.%04d", fw_rev_maj(mdev),
                         fw_rev_min(mdev), fw_rev_sub(mdev));