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Date: Fri, 02 Dec 2016 09:44:53 -0800 From: Eric Dumazet <eric.dumazet@...il.com> To: David Miller <davem@...emloft.net> Cc: netdev <netdev@...r.kernel.org>, Andrey Konovalov <andreyknvl@...gle.com> Subject: [PATCH net] net: avoid signed overflows for SO_{SND|RCV}BUFFORCE From: Eric Dumazet <edumazet@...gle.com> 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@...gle.com> Reported-by: Andrey Konovalov <andreyknvl@...gle.com> --- net/core/sock.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/net/core/sock.c b/net/core/sock.c index 5e3ca414357e2404db28eeacc5e9306051161493..00a074dbfe9bf169c2b81498e6ae265199745b22 100644 --- a/net/core/sock.c +++ b/net/core/sock.c @@ -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:
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