[PATCH] net: ipv4: raw: don't agree to 0 sized headers

From: Sasha Levin
Date: Wed Jul 30 2014 - 09:25:15 EST

For raw sockets, we'd always assume that a header is supplied and will attempt
to copy it into the ip header space using memcpy_fromiovecend():

if (memcpy_fromiovecend((void *)iph, from, 0, length))
goto error_free;

The problem is that memcpy_fromiovecend() assumes that there are actual data
to read from the iovec and doesn't deal with cases where there are none:

int memcpy_fromiovecend(unsigned char *kdata, const struct iovec *iov,
int offset, int len)
/* Skip over the finished iovecs */
while (offset >= iov->iov_len) {
offset -= iov->iov_len;

So when offset == 0 and iov->iov_len == 0, we'll just run iov into random
kernel memory until it hits something bad and dies in a BUG/panic - either
killing the kernel or leaking memory and held locks.

Signed-off-by: Sasha Levin <sasha.levin@xxxxxxxxxx>
net/ipv4/raw.c | 4 ++++
1 file changed, 4 insertions(+)

diff --git a/net/ipv4/raw.c b/net/ipv4/raw.c
index 739db31..3af59ee 100644
--- a/net/ipv4/raw.c
+++ b/net/ipv4/raw.c
@@ -345,6 +345,10 @@ static int raw_send_hdrinc(struct sock *sk, struct flowi4 *fl4,
return -EMSGSIZE;
+ if (length == 0)
+ return -EINVAL;
if (flags&MSG_PROBE)
goto out;


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