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Commit 8db7071f authored by Eric Dumazet's avatar Eric Dumazet Committed by Amit Pundir
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UPSTREAM: net: avoid signed overflows for SO_{SND|RCV}BUFFORCE 



(cherry picked from 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 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>
Change-Id: I2b621c28c02267af5b34a379b2970fe5fb61a4f6
Bug: 33363517
parent dbe53402

net/core/sock.c

+2 −2
Original line number Diff line number Diff line
@@ -733,7 +733,7 @@ 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;
@@ -769,7 +769,7 @@ set_rcvbuf: 
		 * 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: