[PATCH] af_unix: Add sockaddr length checks before accessing sa_family in bind and connect handlers

[Mateusz Jurczyk]

Verify that the caller-provided sockaddr structure is large enough to
contain the sa_family field, before accessing it in bind() and connect()
handlers of the AF_UNIX socket. Since neither syscall enforces a minimum
size of the corresponding memory region, very short sockaddrs (zero or
one byte long) result in operating on uninitialized memory while
referencing .sa_family.

Signed-off-by: Mateusz Jurczyk <mjurc...@google.com>
---
 net/unix/af_unix.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c
index 6a7fe7660551..1a0c961f4ffe 100644
--- a/net/unix/af_unix.c
+++ b/net/unix/af_unix.c
@@ -999,7 +999,8 @@ static int unix_bind(struct socket *sock, struct sockaddr 
*uaddr, int addr_len)
        struct path path = { };
 
        err = -EINVAL;
-       if (sunaddr->sun_family != AF_UNIX)
+       if (addr_len < offsetofend(struct sockaddr_un, sun_family) ||
+           sunaddr->sun_family != AF_UNIX)
                goto out;
 
        if (addr_len == sizeof(short)) {
@@ -1110,6 +1111,10 @@ static int unix_dgram_connect(struct socket *sock, 
struct sockaddr *addr,
        unsigned int hash;
        int err;
 
+       err = -EINVAL;
+       if (alen < offsetofend(struct sockaddr, sa_family))
+               goto out;
+
        if (addr->sa_family != AF_UNSPEC) {
                err = unix_mkname(sunaddr, alen, &hash);
                if (err < 0)
-- 
2.13.1.508.gb3defc5cc-goog