net: avoid signed overflows for SO_{SND|RCV}BUFFORCE
[ Upstream commit b98b0bc8c431e3ceb4b26b0dfc8db509518fb290 ]
CAP_NET_ADMIN users should not be allowed to set negative
sk_sndbuf or sk_rcvbuf values, as it can lead to various memory
corruptions, crashes, OOM...
Note that before commit 82981930125a ("net: cleanups in
sock_setsockopt()"), the bug was even more serious, since SO_SNDBUF
and SO_RCVBUF were vulnerable.
This needs to be backported to all known linux kernels.
Again, many thanks to syzkaller team for discovering this gem.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: Andrey Konovalov <andreyknvl@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/net/core/sock.c b/net/core/sock.c
index 88f01785..f4c0917 100644
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -745,7 +745,7 @@
val = min_t(u32, val, sysctl_wmem_max);
set_sndbuf:
sk->sk_userlocks |= SOCK_SNDBUF_LOCK;
- sk->sk_sndbuf = max_t(u32, val * 2, SOCK_MIN_SNDBUF);
+ sk->sk_sndbuf = max_t(int, val * 2, SOCK_MIN_SNDBUF);
/* Wake up sending tasks if we upped the value. */
sk->sk_write_space(sk);
break;
@@ -781,7 +781,7 @@
* returning the value we actually used in getsockopt
* is the most desirable behavior.
*/
- sk->sk_rcvbuf = max_t(u32, val * 2, SOCK_MIN_RCVBUF);
+ sk->sk_rcvbuf = max_t(int, val * 2, SOCK_MIN_RCVBUF);
break;
case SO_RCVBUFFORCE:
