From: "Naveen N. Rao" <naveen.n.rao@linux.vnet.ibm.com>
To: Michael Ellerman <mpe@ellerman.id.au>
Cc: Masami Hiramatsu <mhiramat@kernel.org>,
David Laight <David.Laight@ACULAB.COM>,
Paul Clarke <pc@us.ibm.com>,
Ananth N Mavinakayanahalli <ananth@linux.vnet.ibm.com>,
linuxppc-dev@lists.ozlabs.org
Subject: [PATCH] powerpc/kprobes: refactor kprobe_lookup_name for safer string operations
Date: Tue, 25 Apr 2017 21:37:11 +0530 [thread overview]
Message-ID: <20170425160711.15332-1-naveen.n.rao@linux.vnet.ibm.com> (raw)
Use safer string manipulation functions when dealing with a
user-provided string in kprobe_lookup_name().
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 | 47 ++++++++++++++++++-------------------------
1 file changed, 20 insertions(+), 27 deletions(-)
diff --git a/arch/powerpc/kernel/kprobes.c b/arch/powerpc/kernel/kprobes.c
index 160ae0fa7d0d..5a17e6467be9 100644
--- a/arch/powerpc/kernel/kprobes.c
+++ b/arch/powerpc/kernel/kprobes.c
@@ -53,7 +53,7 @@ bool arch_within_kprobe_blacklist(unsigned long addr)
kprobe_opcode_t *kprobe_lookup_name(const char *name, unsigned int offset)
{
- kprobe_opcode_t *addr;
+ kprobe_opcode_t *addr = NULL;
#ifdef PPC64_ELF_ABI_v2
/* PPC64 ABIv2 needs local entry point */
@@ -85,36 +85,29 @@ kprobe_opcode_t *kprobe_lookup_name(const char *name, unsigned int offset)
* Also handle <module:symbol> format.
*/
char dot_name[MODULE_NAME_LEN + 1 + KSYM_NAME_LEN];
- const char *modsym;
bool dot_appended = false;
- if ((modsym = strchr(name, ':')) != NULL) {
- modsym++;
- if (*modsym != '\0' && *modsym != '.') {
- /* Convert to <module:.symbol> */
- strncpy(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);
- dot_appended = true;
- } else {
- dot_name[0] = '\0';
- strncat(dot_name, name, sizeof(dot_name) - 1);
- }
- } else if (name[0] != '.') {
- dot_name[0] = '.';
- dot_name[1] = '\0';
- strncat(dot_name, name, KSYM_NAME_LEN - 2);
+ const char *c;
+ ssize_t ret = 0;
+ int len = 0;
+
+ if ((c = strnchr(name, MODULE_NAME_LEN, ':')) != NULL) {
+ c++;
+ len = c - name;
+ memcpy(dot_name, name, len);
+ } else
+ c = name;
+
+ if (*c != '\0' && *c != '.') {
+ dot_name[len++] = '.';
dot_appended = true;
- } else {
- dot_name[0] = '\0';
- strncat(dot_name, name, KSYM_NAME_LEN - 1);
}
- addr = (kprobe_opcode_t *)kallsyms_lookup_name(dot_name);
- if (!addr && dot_appended) {
- /* Let's try the original non-dot symbol lookup */
+ ret = strscpy(dot_name + len, c, KSYM_NAME_LEN);
+ if (ret >= 0)
+ addr = (kprobe_opcode_t *)kallsyms_lookup_name(dot_name);
+
+ /* Fallback to the original non-dot symbol lookup */
+ if (!addr && dot_appended)
addr = (kprobe_opcode_t *)kallsyms_lookup_name(name);
- }
#else
addr = (kprobe_opcode_t *)kallsyms_lookup_name(name);
#endif
--
2.12.1
next reply other threads:[~2017-04-25 16:08 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-04-25 16:07 Naveen N. Rao [this message]
2017-04-26 4:41 ` [PATCH] powerpc/kprobes: refactor kprobe_lookup_name for safer string operations Masami Hiramatsu
2017-04-26 18:42 ` Naveen N. Rao
2017-04-27 11:31 ` Michael Ellerman
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