linux-kernel - [PATCH v3] mach-omap2: fixing wrong strcat for Non-NULL terminated string

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Date:   Mon, 05 Dec 2016 10:57:13 +0530
From:   Maninder Singh <maninder1.s@...sung.com>
To:     bcousson@...libre.com, paul@...an.com, tony@...mide.com,
        linux@...linux.org.uk
Cc:     linux-omap@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-kernel@...r.kernel.org, pankaj.m@...sung.com,
        ajeet.y@...sung.com, Maninder Singh <maninder1.s@...sung.com>,
        Vaneet Narang <v.narang@...sung.com>
Subject: [PATCH v3] mach-omap2: fixing wrong strcat for Non-NULL terminated
 string

Issue caught with static analysis tool:
"Dangerous usage of 'name' (strncpy doesn't always 0-terminate it)"

Use strlcpy _includes_ the NUL terminator, and  strlcat() which ensures 
that it won't overflow the buffer.

Reported-by: Maninder Singh <maninder1.s@...sung.com>
Signed-off-by: Vaneet Narang <v.narang@...sung.com>
Signed-off-by: Russell King <linux@...linux.org.uk>
---
v1 -> v2: changed strncpy to strlcpy
v2 -> v3: use of strlcat as suggested by Russell to
	  make change clearer and simpler.

 arch/arm/mach-omap2/omap_hwmod.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/arch/arm/mach-omap2/omap_hwmod.c b/arch/arm/mach-omap2/omap_hwmod.c
index 759e1d4..e8b9887 100644
--- a/arch/arm/mach-omap2/omap_hwmod.c
+++ b/arch/arm/mach-omap2/omap_hwmod.c
@@ -741,14 +741,14 @@ static int _init_main_clk(struct omap_hwmod *oh)
 	int ret = 0;
 	char name[MOD_CLK_MAX_NAME_LEN];
 	struct clk *clk;
+	static const char modck[] = "_mod_ck";
 
-	/* +7 magic comes from '_mod_ck' suffix */
-	if (strlen(oh->name) + 7 > MOD_CLK_MAX_NAME_LEN)
+	if (strlen(oh->name) >= MOD_CLK_MAX_NAME_LEN - strlen(modck))
 		pr_warn("%s: warning: cropping name for %s\n", __func__,
 			oh->name);
 
-	strncpy(name, oh->name, MOD_CLK_MAX_NAME_LEN - 7);
-	strcat(name, "_mod_ck");
+	strlcpy(name, oh->name, MOD_CLK_MAX_NAME_LEN - strlen(modck));
+	strlcat(name, modck, MOD_CLK_MAX_NAME_LEN);
 
 	clk = clk_get(NULL, name);
 	if (!IS_ERR(clk)) {
-- 
1.9.1