2017-10-31 13:24:35 -04:00
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From b98b0bc8c431e3ceb4b26b0dfc8db509518fb290 Mon Sep 17 00:00:00 2001
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From: Eric Dumazet <edumazet@google.com>
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Date: Fri, 2 Dec 2016 09:44:53 -0800
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Subject: net: avoid signed overflows for SO_{SND|RCV}BUFFORCE
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CAP_NET_ADMIN users should not be allowed to set negative
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sk_sndbuf or sk_rcvbuf values, as it can lead to various memory
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corruptions, crashes, OOM...
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Note that before commit 82981930125a ("net: cleanups in
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sock_setsockopt()"), the bug was even more serious, since SO_SNDBUF
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and SO_RCVBUF were vulnerable.
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This needs to be backported to all known linux kernels.
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Again, many thanks to syzkaller team for discovering this gem.
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Signed-off-by: Eric Dumazet <edumazet@google.com>
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Reported-by: Andrey Konovalov <andreyknvl@google.com>
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Signed-off-by: David S. Miller <davem@davemloft.net>
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---
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net/core/sock.c | 4 ++--
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1 file changed, 2 insertions(+), 2 deletions(-)
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diff --git a/net/core/sock.c b/net/core/sock.c
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index 5e3ca41..00a074d 100644
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--- a/net/core/sock.c
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+++ b/net/core/sock.c
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@@ -715,7 +715,7 @@ int sock_setsockopt(struct socket *sock, int level, int optname,
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val = min_t(u32, val, sysctl_wmem_max);
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set_sndbuf:
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sk->sk_userlocks |= SOCK_SNDBUF_LOCK;
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- sk->sk_sndbuf = max_t(u32, val * 2, SOCK_MIN_SNDBUF);
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+ sk->sk_sndbuf = max_t(int, val * 2, SOCK_MIN_SNDBUF);
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/* Wake up sending tasks if we upped the value. */
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sk->sk_write_space(sk);
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break;
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@@ -751,7 +751,7 @@ set_rcvbuf:
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* returning the value we actually used in getsockopt
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* is the most desirable behavior.
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*/
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- sk->sk_rcvbuf = max_t(u32, val * 2, SOCK_MIN_RCVBUF);
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+ sk->sk_rcvbuf = max_t(int, val * 2, SOCK_MIN_RCVBUF);
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break;
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case SO_RCVBUFFORCE:
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--
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cgit v1.1
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