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-4.4.y commit a1402232e193 for gcc 9 build]
Signed-off-by: Seung-Woo Kim <sw0312.kim@samsung.com>
Change-Id: Idd3506f5ee90d7ff4811294d8590478a28d5ea1e

diff --git a/drivers/net/wireless/ath/ath10k/wmi.c b/drivers/net/wireless/ath/ath10k/wmi.c
index f201e50447d8950c6681e50b3454bd42e22cf083..b867875aa6e66cfe017a59c8b38fd54284c4719f 100644 (file)
--- a/drivers/net/wireless/ath/ath10k/wmi.c
+++ b/drivers/net/wireless/ath/ath10k/wmi.c
@@ -4065,7 +4065,7 @@ 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];