net: 4 bytes kernel memory disclosure in SO_BSDCOMPAT gsopt try #2
In function sock_getsockopt() located in net/core/sock.c, optval v.val
is not correctly initialized and directly returned in userland in case
we have SO_BSDCOMPAT option set.
This dummy code should trigger the bug:
int main(void)
{
unsigned char buf[4] = { 0, 0, 0, 0 };
int len;
int sock;
sock = socket(33, 2, 2);
getsockopt(sock, 1, SO_BSDCOMPAT, &buf, &len);
printf("%x%x%x%x\n", buf[0], buf[1], buf[2], buf[3]);
close(sock);
}
Here is a patch that fix this bug by initalizing v.val just after its
declaration.
Signed-off-by: Clément Lecigne <clement.lecigne@netasq.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/core/sock.c b/net/core/sock.c
index f3a0d08..6f2e133 100644
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -696,6 +696,8 @@
if (len < 0)
return -EINVAL;
+ v.val = 0;
+
switch(optname) {
case SO_DEBUG:
v.val = sock_flag(sk, SOCK_DBG);