From: Pablo Neira <[email protected]>
3.12-stable review patch. If anyone has any objections, please let me know.
===============
[ Upstream commit 8b7b932434f5eee495b91a2804f5b64ebb2bc835 ]
nla_strcmp compares the string length plus one, so it's implicitly
including the nul-termination in the comparison.
int nla_strcmp(const struct nlattr *nla, const char *str)
{
int len = strlen(str) + 1;
...
d = memcmp(nla_data(nla), str, len);
However, if NLA_STRING is used, userspace can send us a string without
the nul-termination. This is a problem since the string
comparison will not match as the last byte may be not the
nul-termination.
Fix this by skipping the comparison of the nul-termination if the
attribute data is nul-terminated. Suggested by Thomas Graf.
Cc: Florian Westphal <[email protected]>
Cc: Thomas Graf <[email protected]>
Signed-off-by: Pablo Neira Ayuso <[email protected]>
Signed-off-by: David S. Miller <[email protected]>
Signed-off-by: Jiri Slaby <[email protected]>
---
lib/nlattr.c | 10 ++++++++--
1 file changed, 8 insertions(+), 2 deletions(-)
diff --git a/lib/nlattr.c b/lib/nlattr.c
index 18eca7809b08..fc6754720ced 100644
--- a/lib/nlattr.c
+++ b/lib/nlattr.c
@@ -303,9 +303,15 @@ int nla_memcmp(const struct nlattr *nla, const void *data,
*/
int nla_strcmp(const struct nlattr *nla, const char *str)
{
- int len = strlen(str) + 1;
- int d = nla_len(nla) - len;
+ int len = strlen(str);
+ char *buf = nla_data(nla);
+ int attrlen = nla_len(nla);
+ int d;
+ if (attrlen > 0 && buf[attrlen - 1] == '\0')
+ attrlen--;
+
+ d = attrlen - len;
if (d == 0)
d = memcmp(nla_data(nla), str, len);
--
1.9.2
--
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