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powerpc/kprobes: refactor kprobe_lookup_name for safer string operations

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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>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
This commit is contained in:
Naveen N. Rao 2017-10-23 22:07:41 +05:30 committed by Michael Ellerman
parent 67ac0bfe29
commit acdfe93101
1 changed files with 20 additions and 27 deletions
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47
arch/powerpc/kernel/kprobes.c
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@ -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