linux-kernel - [PATCH v4 4/7] powerpc/kprobes: Use safer string functions in kprobe_lookup

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Date:   Fri, 21 Apr 2017 18:03:20 +0530
From:   "Naveen N. Rao" <naveen.n.rao@...ux.vnet.ibm.com>
To:     Michael Ellerman <mpe@...erman.id.au>,
        Masami Hiramatsu <mhiramat@...nel.org>
Cc:     Ananth N Mavinakayanahalli <ananth@...ux.vnet.ibm.com>,
        Ingo Molnar <mingo@...nel.org>, linuxppc-dev@...ts.ozlabs.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH v4 4/7] powerpc/kprobes: Use safer string functions in kprobe_lookup_name()

Convert usage of strchr()/strncpy()/strncat() to
strnchr()/memcpy()/strlcat() for simpler and safer string manipulation.

Reported-by: David Laight <David.Laight@...LAB.COM>
Signed-off-by: Naveen N. Rao <naveen.n.rao@...ux.vnet.ibm.com>
---
Changes: Additionally convert the strchr().


 arch/powerpc/kernel/kprobes.c | 13 ++++++-------
 1 file changed, 6 insertions(+), 7 deletions(-)

diff --git a/arch/powerpc/kernel/kprobes.c b/arch/powerpc/kernel/kprobes.c
index 97b5eed1f76d..c73fb6e3b43f 100644
--- a/arch/powerpc/kernel/kprobes.c
+++ b/arch/powerpc/kernel/kprobes.c
@@ -65,28 +65,27 @@ kprobe_opcode_t *kprobe_lookup_name(const char *name, unsigned int offset)
 	char dot_name[MODULE_NAME_LEN + 1 + KSYM_NAME_LEN];
 	const char *modsym;
 	bool dot_appended = false;
-	if ((modsym = strchr(name, ':')) != NULL) {
+	if ((modsym = strnchr(name, ':', MODULE_NAME_LEN)) != NULL) {
 		modsym++;
 		if (*modsym != '\0' && *modsym != '.') {
 			/* Convert to <module:.symbol> */
-			strncpy(dot_name, name, modsym - name);
+			memcpy(dot_name, name, modsym - name);
 			dot_name[modsym - name] = '.';
 			dot_name[modsym - name + 1] = '\0';
-			strncat(dot_name, modsym,
-				sizeof(dot_name) - (modsym - name) - 2);
+			strlcat(dot_name, modsym, sizeof(dot_name));
 			dot_appended = true;
 		} else {
 			dot_name[0] = '\0';
-			strncat(dot_name, name, sizeof(dot_name) - 1);
+			strlcat(dot_name, name, sizeof(dot_name));
 		}
 	} else if (name[0] != '.') {
 		dot_name[0] = '.';
 		dot_name[1] = '\0';
-		strncat(dot_name, name, KSYM_NAME_LEN - 2);
+		strlcat(dot_name, name, sizeof(dot_name));
 		dot_appended = true;
 	} else {
 		dot_name[0] = '\0';
-		strncat(dot_name, name, KSYM_NAME_LEN - 1);
+		strlcat(dot_name, name, sizeof(dot_name));
 	}
 	addr = (kprobe_opcode_t *)kallsyms_lookup_name(dot_name);
 	if (!addr && dot_appended) {
-- 
2.12.1