Bluetooth: RFCOMM: Fix not validating setsockopt user input

[ Upstream commit a97de7bff13b1cc825c1b1344eaed8d6c2d3e695 ]

syzbot reported rfcomm_sock_setsockopt_old() is copying data without
checking user input length.

BUG: KASAN: slab-out-of-bounds in copy_from_sockptr_offset
include/linux/sockptr.h:49 [inline]
BUG: KASAN: slab-out-of-bounds in copy_from_sockptr
include/linux/sockptr.h:55 [inline]
BUG: KASAN: slab-out-of-bounds in rfcomm_sock_setsockopt_old
net/bluetooth/rfcomm/sock.c:632 [inline]
BUG: KASAN: slab-out-of-bounds in rfcomm_sock_setsockopt+0x893/0xa70
net/bluetooth/rfcomm/sock.c:673
Read of size 4 at addr ffff8880209a8bc3 by task syz-executor632/5064

Fixes: 9f2c8a03fbb3 ("Bluetooth: Replace RFCOMM link mode with security level")
Fixes: bb23c0ab8246 ("Bluetooth: Add support for deferring RFCOMM connection setup")
Reported-by: syzbot <syzkaller@googlegroups.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/net/bluetooth/rfcomm/sock.c b/net/bluetooth/rfcomm/sock.c
index b54e8a530f55a1ff9547a2a5546db34059ebd672..29aa07e9db9d7122bac6ac0c6dfcd76765f11cb8 100644 (file)
--- a/net/bluetooth/rfcomm/sock.c
+++ b/net/bluetooth/rfcomm/sock.c
@@ -629,7 +629,7 @@ static int rfcomm_sock_setsockopt_old(struct socket *sock, int optname,
 
        switch (optname) {
        case RFCOMM_LM:
-               if (copy_from_sockptr(&opt, optval, sizeof(u32))) {
+               if (bt_copy_from_sockptr(&opt, sizeof(opt), optval, optlen)) {
                        err = -EFAULT;
                        break;
                }
@@ -664,7 +664,6 @@ static int rfcomm_sock_setsockopt(struct socket *sock, int level, int optname,
        struct sock *sk = sock->sk;
        struct bt_security sec;
        int err = 0;
-       size_t len;
        u32 opt;
 
        BT_DBG("sk %p", sk);
@@ -686,11 +685,9 @@ static int rfcomm_sock_setsockopt(struct socket *sock, int level, int optname,
 
                sec.level = BT_SECURITY_LOW;
 
-               len = min_t(unsigned int, sizeof(sec), optlen);
-               if (copy_from_sockptr(&sec, optval, len)) {
-                       err = -EFAULT;
+               err = bt_copy_from_sockptr(&sec, sizeof(sec), optval, optlen);
+               if (err)
                        break;
-               }
 
                if (sec.level > BT_SECURITY_HIGH) {
                        err = -EINVAL;
@@ -706,10 +703,9 @@ static int rfcomm_sock_setsockopt(struct socket *sock, int level, int optname,
                        break;
                }
 
-               if (copy_from_sockptr(&opt, optval, sizeof(u32))) {
-                       err = -EFAULT;
+               err = bt_copy_from_sockptr(&opt, sizeof(opt), optval, optlen);
+               if (err)
                        break;
-               }
 
                if (opt)
                        set_bit(BT_SK_DEFER_SETUP, &bt_sk(sk)->flags);