[PATCH 3.16 151/254] af_key: fix buffer overread in parse_exthdrs()

Ben Hutchings
2018-02-28T15:58:53Z

From: Eric Biggers <ebiggers@google.com>

commit 4e765b4972af7b07adcb1feb16e7a525ce1f6b28 upstream.

If a message sent to a PF_KEY socket ended with an incomplete extension
header (fewer than 4 bytes remaining), then parse_exthdrs() read past
the end of the message, into uninitialized memory. Fix it by returning
-EINVAL in this case.

Reproducer:

#include <linux/pfkeyv2.h>
#include <sys/socket.h>
#include <unistd.h>

int main()
{
int sock = socket(PF_KEY, SOCK_RAW, PF_KEY_V2);
char buf[17] = { 0 };
struct sadb_msg *msg = (void *)buf;

msg->sadb_msg_version = PF_KEY_V2;
msg->sadb_msg_type = SADB_DELETE;
msg->sadb_msg_len = 2;

write(sock, buf, 17);
}

Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
net/key/af_key.c | 3 +++
1 file changed, 3 insertions(+)

--- a/net/key/af_key.c
+++ b/net/key/af_key.c
@@ -513,6 +513,9 @@ static int parse_exthdrs(struct sk_buff
uint16_t ext_type;
int ext_len;

+ if (len < sizeof(*ehdr))
+ return -EINVAL;
+
ext_len = ehdr->sadb_ext_len;
ext_len *= sizeof(uint64_t);
ext_type = ehdr->sadb_ext_type;