netdev - [PATCH AUTOSEL 4.9 83/91] net: fix possible overflow in __sk_mem_raise

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Date:   Fri, 22 Nov 2019 01:01:21 -0500
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Eric Dumazet <edumazet@...gle.com>,
        "David S . Miller" <davem@...emloft.net>,
        Sasha Levin <sashal@...nel.org>, netdev@...r.kernel.org
Subject: [PATCH AUTOSEL 4.9 83/91] net: fix possible overflow in __sk_mem_raise_allocated()

From: Eric Dumazet <edumazet@...gle.com>

[ Upstream commit 5bf325a53202b8728cf7013b72688c46071e212e ]

With many active TCP sockets, fat TCP sockets could fool
__sk_mem_raise_allocated() thanks to an overflow.

They would increase their share of the memory, instead
of decreasing it.

Signed-off-by: Eric Dumazet <edumazet@...gle.com>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 include/net/sock.h | 2 +-
 net/core/sock.c    | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/include/net/sock.h b/include/net/sock.h
index d8d14ae8892a7..aed436567d70b 100644
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -1201,7 +1201,7 @@ static inline void sk_sockets_allocated_inc(struct sock *sk)
 	percpu_counter_inc(sk->sk_prot->sockets_allocated);
 }
 
-static inline int
+static inline u64
 sk_sockets_allocated_read_positive(struct sock *sk)
 {
 	return percpu_counter_read_positive(sk->sk_prot->sockets_allocated);
diff --git a/net/core/sock.c b/net/core/sock.c
index d224933514074..41794a698da66 100644
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -2156,7 +2156,7 @@ int __sk_mem_schedule(struct sock *sk, int size, int kind)
 	}
 
 	if (sk_has_memory_pressure(sk)) {
-		int alloc;
+		u64 alloc;
 
 		if (!sk_under_memory_pressure(sk))
 			return 1;
-- 
2.20.1