[v3,4/7] powerpc: kprobes: use safer string functions in kprobe_lookup_name()

Submitted by Naveen N. Rao on April 19, 2017, 12:51 p.m.

Details

Message ID d8a1de28324a2350483a961be078a6343111632b.1492604782.git.naveen.n.rao@linux.vnet.ibm.com
State Superseded
Headers show

Commit Message

Naveen N. Rao April 19, 2017, 12:51 p.m.
Convert usage of strncpy()/strncat() to memcpy()/strlcat() for simpler
and safer string manipulation.

Reported-by: David Laight <David.Laight@ACULAB.COM>
Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
---
 arch/powerpc/kernel/kprobes.c | 11 +++++------
 1 file changed, 5 insertions(+), 6 deletions(-)

Comments

David Laight April 21, 2017, 3:06 p.m.
From: Naveen N. Rao
> Sent: 19 April 2017 13:51
...
>  			dot_name[0] = '\0';
> -			strncat(dot_name, name, sizeof(dot_name) - 1);
> +			strlcat(dot_name, name, sizeof(dot_name));
...

Is that really zeroing the first byte just so it can append to it?

	David

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diff --git a/arch/powerpc/kernel/kprobes.c b/arch/powerpc/kernel/kprobes.c
index 97b5eed1f76d..d743bacefa8c 100644
--- a/arch/powerpc/kernel/kprobes.c
+++ b/arch/powerpc/kernel/kprobes.c
@@ -69,24 +69,23 @@  kprobe_opcode_t *kprobe_lookup_name(const char *name, unsigned int offset)
 		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) {