[PATCH AUTOSEL 4.14 112/127] net: fix possible overflow in __sk_mem_raise_allocated()

Sasha Levin
2019-11-22T05:58:48Z

From: Eric Dumazet <edumazet@google.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@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.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 780c6c0a86f04..0af46cbd3649c 100644
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -1232,7 +1232,7 @@ 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 7ccbcd853cbce..90ccbbf9e6b00 100644
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -2357,7 +2357,7 @@ int __sk_mem_raise_allocated(struct sock *sk, int size, int amt, int kind)
}

if (sk_has_memory_pressure(sk)) {
- int alloc;
+ u64 alloc;

if (!sk_under_memory_pressure(sk))
return 1;
--
2.20.1