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Commit b98b0bc8 authored by Eric Dumazet's avatar Eric Dumazet Committed by David S. Miller
Browse files

net: avoid signed overflows for SO_{SND|RCV}BUFFORCE 



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 82981930 ("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: default avatarEric Dumazet <edumazet@google.com>
Reported-by: default avatarAndrey Konovalov <andreyknvl@google.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 5b010147

net/core/sock.c

+2 −2
Original line number Diff line number Diff line
@@ -715,7 +715,7 @@ int sock_setsockopt(struct socket *sock, int level, int optname, 
		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;
@@ -751,7 +751,7 @@ int sock_setsockopt(struct socket *sock, int level, int optname, 
		 * 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: