net/mlx5e: Correct snprintf truncation handling for fw_version buffer

[ Upstream commit ad436b9c1270c40554e274f067f1b78fcc06a004 ]

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>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en_ethtool.c b/drivers/net/ethernet/mellanox/mlx5/core/en_ethtool.c
index 7c66bd73ddfa25713c2136fba5985dff1ce13c2a..38263d5c98b344adcf702f5b6c2310337020b147 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));