[PATCH 6.1 035/127] net: annotate data-races around sk->sk_reserved_mem

Greg Kroah-Hartman
2023-08-09T10:53:10Z

From: Eric Dumazet <edumazet@google.com>

[ Upstream commit fe11fdcb4207907d80cda2e73777465d68131e66 ]

sk_getsockopt() runs locklessly. This means sk->sk_reserved_mem
can be read while other threads are changing its value.

Add missing annotations where they are needed.

Fixes: 2bb2f5fb21b0 ("net: add new socket option SO_RESERVE_MEM")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Wei Wang <weiwan@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
net/core/sock.c | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/net/core/sock.c b/net/core/sock.c
index 0c1baa5517f11..9483820833c5b 100644
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -996,7 +996,7 @@ static void sock_release_reserved_memory(struct sock *sk, int bytes)
bytes = round_down(bytes, PAGE_SIZE);

WARN_ON(bytes > sk->sk_reserved_mem);
- sk->sk_reserved_mem -= bytes;
+ WRITE_ONCE(sk->sk_reserved_mem, sk->sk_reserved_mem - bytes);
sk_mem_reclaim(sk);
}

@@ -1033,7 +1033,8 @@ static int sock_reserve_memory(struct sock *sk, int bytes)
}
sk->sk_forward_alloc += pages << PAGE_SHIFT;

- sk->sk_reserved_mem += pages << PAGE_SHIFT;
+ WRITE_ONCE(sk->sk_reserved_mem,
+ sk->sk_reserved_mem + (pages << PAGE_SHIFT));

return 0;
}
@@ -1922,7 +1923,7 @@ int sk_getsockopt(struct sock *sk, int level, int optname,
break;

case SO_RESERVE_MEM:
- v.val = sk->sk_reserved_mem;
+ v.val = READ_ONCE(sk->sk_reserved_mem);
break;

case SO_TXREHASH:
--
2.40.1