[PATCH net v3 3/4] rxrpc: Improve setsockopt() handling of malformed user input

[Michal Luczaj]

copy_from_sockptr() does not return negative value on error; instead, it
reports the number of bytes that failed to copy. Since it's deprecated,
switch to copy_safe_from_sockptr().

Note: Keeping the `optlen != sizeof(unsigned int)` check as
copy_safe_from_sockptr() by itself would also accept
optlen > sizeof(unsigned int). Which would allow a more lenient handling
of inputs.

Fixes: 17926a79320a ("[AF_RXRPC]: Provide secure RxRPC sockets for use by userspace and kernel both")
Signed-off-by: Michal Luczaj <mhal at rbox.co>
---
 net/rxrpc/af_rxrpc.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/net/rxrpc/af_rxrpc.c b/net/rxrpc/af_rxrpc.c
index f4844683e12039d636253cb06f622468593487eb..9d8bd0b37e41da9f99e2661ae4a29569f5eab650 100644
--- a/net/rxrpc/af_rxrpc.c
+++ b/net/rxrpc/af_rxrpc.c
@@ -707,9 +707,10 @@ static int rxrpc_setsockopt(struct socket *sock, int level, int optname,
 			ret = -EISCONN;
 			if (rx->sk.sk_state != RXRPC_UNBOUND)
 				goto error;
-			ret = copy_from_sockptr(&min_sec_level, optval,
-				       sizeof(unsigned int));
-			if (ret < 0)
+			ret = copy_safe_from_sockptr(&min_sec_level,
+						     sizeof(min_sec_level),
+						     optval, optlen);
+			if (ret)
 				goto error;
 			ret = -EINVAL;
 			if (min_sec_level > RXRPC_SECURITY_MAX)

-- 
2.46.2