ath10k: avoid possible string overflow

commit 6707ba0105a2d350710bc0a537a98f49eb4b895d upstream.

The way that 'strncat' is used here raised a warning in gcc-8:

drivers/net/wireless/ath/ath10k/wmi.c: In function 'ath10k_wmi_tpc_stats_final_disp_tables':
drivers/net/wireless/ath/ath10k/wmi.c:4649:4: error: 'strncat' output truncated before terminating nul copying as many bytes from a string as its length [-Werror=stringop-truncation]

Effectively, this is simply a strcat() but the use of strncat() suggests
some form of overflow check. Regardless of whether this might actually
overflow, using strlcat() instead of strncat() avoids the warning and
makes the code more robust.

Fixes: bc64d05220f3 ("ath10k: debugfs support to get final TPC stats for 10.4 variants")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
[sw0312.kim: cherry-pick from stable linux-4.14.y commit 0cc17a7a3203 for gcc 9 build]
Signed-off-by: Seung-Woo Kim <sw0312.kim@samsung.com>
Change-Id: I9e104bff8046c7ffa7f50b047dc4cd2e9fdb83e6

diff --git a/drivers/net/wireless/ath/ath10k/wmi.c b/drivers/net/wireless/ath/ath10k/wmi.c
index 8cb4785..ab8eb9c 100644 (file)
--- a/drivers/net/wireless/ath/ath10k/wmi.c
+++ b/drivers/net/wireless/ath/ath10k/wmi.c
@@ -4309,7 +4309,7 @@ static void ath10k_tpc_config_disp_tables(struct ath10k *ar,
                                                            rate_code[i],
                                                            type);
                        snprintf(buff, sizeof(buff), "%8d ", tpc[j]);
-                       strncat(tpc_value, buff, strlen(buff));
+                       strlcat(tpc_value, buff, sizeof(tpc_value));
                }
                tpc_stats->tpc_table[type].pream_idx[i] = pream_idx;
                tpc_stats->tpc_table[type].rate_code[i] = rate_code[i];