On 7/24/20 2:14 PM, Jacob Keller wrote:
On 7/23/2020 12:35 PM, Eric Dumazet wrote:
On 7/23/20 11:21 AM, Mark Salyzyn wrote:
Many of the nla_get_* inlines fail to check attribute's length before
copying the content resulting in possible out-of-boundary accesses.
Adjust the inlines to perform nla_len checking, for the most part
using the nla_memcpy function to faciliate since these are not
necessarily performance critical and do not need a likely fast path.
Signed-off-by: Mark Salyzyn <saly...@android.com>
Cc: netdev@vger.kernel.org
Cc: linux-ker...@vger.kernel.org
Cc: kernel-t...@android.com
Cc: "David S. Miller" <da...@davemloft.net>
Cc: Jakub Kicinski <k...@kernel.org>
Cc: Thomas Graf <tg...@suug.ch>
Fixes: bfa83a9e03cf ("[NETLINK]: Type-safe netlink messages/attributes
interface")
---
include/net/netlink.h | 66 +++++++++++++++++++++++++++++++++++--------
1 file changed, 54 insertions(+), 12 deletions(-)
diff --git a/include/net/netlink.h b/include/net/netlink.h
index c0411f14fb53..11c0f153be7c 100644
--- a/include/net/netlink.h
+++ b/include/net/netlink.h
@@ -1538,7 +1538,11 @@ static inline int nla_put_bitfield32(struct sk_buff
*skb, int attrtype,
*/
static inline u32 nla_get_u32(const struct nlattr *nla)
{
- return *(u32 *) nla_data(nla);
+ u32 tmp;
+
+ nla_memcpy(&tmp, nla, sizeof(tmp));
+
+ return tmp;
I believe this will hide bugs, that syzbot was able to catch.
Instead, you could perhaps introduce a CONFIG_DEBUG_NETLINK option,
and add a WARN_ON_ONCE(nla_len(nla) < sizeof(u32)) so that we can detect bugs
in callers.
I also think this is a better approach.
We (another engineer here) are looking into that and will get back to
everyone.
Sincerely -- Mark Salyzyn
