[NET]: Reject socket filter if division by constant zero is attempted.

This way we don't have to check it in sk_run_filter().

Signed-off-by: Kris Katterjohn <kjak@users.sourceforge.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 4 insertions, 2 deletions

diff --git a/net/core/filter.c b/net/core/filter.c
index 079c2edff789..2841bfce29d6 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -116,8 +116,6 @@ int sk_run_filter(struct sk_buff *skb, struct sock_filter *filter, int flen)
                         A /= X;
                         continue;
                 case BPF_ALU|BPF_DIV|BPF_K:
-                        if (fentry->k == 0)
-                                return 0;
                         A /= fentry->k;
                         continue;
                 case BPF_ALU|BPF_AND|BPF_X:
@@ -320,6 +318,10 @@ int sk_chk_filter(struct sock_filter *filter, int flen)
                         }
                 }
 
+                /* check for division by zero   -Kris Katterjohn 2005-10-30 */
+                if (ftest->code == (BPF_ALU|BPF_DIV|BPF_K) && ftest->k == 0)
+                        return -EINVAL;
+
                 /* check that memory operations use valid addresses. */
                 if (ftest->k >= BPF_MEMWORDS) {
                         /* but it might not be a memory operation... */