[PATCH] Prevent reading uninitialized memory with socket filters

[Dan Rosenberg <drosenberg@vsecurity.com>]

The "mem" array used as scratch space for socket filters is not
initialized, allowing unprivileged users to leak kernel stack bytes.

Signed-off-by: Dan Rosenberg <drosenberg@vsecurity.com>

---
 net/core/filter.c               |    2 ++
 1 file changed, 2 insertions(+), 0 deletions(-)

diff --git a/net/core/filter.c b/net/core/filter.c
index 7beaec3..2749ba0 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -121,6 +121,8 @@ unsigned int sk_run_filter(struct sk_buff *skb, struct sock_filter *filter, int
 	int k;
 	int pc;
 
+	memset(mem, 0, sizeof(mem));
+
 	/*
 	 * Process array of filter instructions.
 	 */