Commit c5167248 authored by Eric Dumazet's avatar Eric Dumazet Committed by Ben Hutchings

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

commit b98b0bc8 upstream.

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>
Signed-off-by: default avatarBen Hutchings <ben@decadent.org.uk>
parent e30250c9
...@@ -541,7 +541,7 @@ int sock_setsockopt(struct socket *sock, int level, int optname, ...@@ -541,7 +541,7 @@ int sock_setsockopt(struct socket *sock, int level, int optname,
val = min_t(u32, val, sysctl_wmem_max); val = min_t(u32, val, sysctl_wmem_max);
set_sndbuf: set_sndbuf:
sk->sk_userlocks |= SOCK_SNDBUF_LOCK; 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. */ /* Wake up sending tasks if we upped the value. */
sk->sk_write_space(sk); sk->sk_write_space(sk);
break; break;
...@@ -577,7 +577,7 @@ int sock_setsockopt(struct socket *sock, int level, int optname, ...@@ -577,7 +577,7 @@ int sock_setsockopt(struct socket *sock, int level, int optname,
* returning the value we actually used in getsockopt * returning the value we actually used in getsockopt
* is the most desirable behavior. * 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; break;
case SO_RCVBUFFORCE: case SO_RCVBUFFORCE:
......
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