[PATCH 5.16 0600/1017] bpf, sockmap: Fix memleak in tcp_bpf_sendmsg while sk msg is full

Greg Kroah-Hartman
2022-04-05T12:56:51Z

From: Wang Yufen <wangyufen@huawei.com>

[ Upstream commit 9c34e38c4a870eb30b13f42f5b44f42e9d19ccb8 ]

If tcp_bpf_sendmsg() is running while sk msg is full. When sk_msg_alloc()
returns -ENOMEM error, tcp_bpf_sendmsg() goes to wait_for_memory. If partial
memory has been alloced by sk_msg_alloc(), that is, msg_tx->sg.size is
greater than osize after sk_msg_alloc(), memleak occurs. To fix we use
sk_msg_trim() to release the allocated memory, then goto wait for memory.

Other call paths of sk_msg_alloc() have the similar issue, such as
tls_sw_sendmsg(), so handle sk_msg_trim logic inside sk_msg_alloc(),
as Cong Wang suggested.

This issue can cause the following info:
WARNING: CPU: 3 PID: 7950 at net/core/stream.c:208 sk_stream_kill_queues+0xd4/0x1a0
Call Trace:
<TASK>
inet_csk_destroy_sock+0x55/0x110
__tcp_close+0x279/0x470
tcp_close+0x1f/0x60
inet_release+0x3f/0x80
__sock_release+0x3d/0xb0
sock_close+0x11/0x20
__fput+0x92/0x250
task_work_run+0x6a/0xa0
do_exit+0x33b/0xb60
do_group_exit+0x2f/0xa0
get_signal+0xb6/0x950
arch_do_signal_or_restart+0xac/0x2a0
exit_to_user_mode_prepare+0xa9/0x200
syscall_exit_to_user_mode+0x12/0x30
do_syscall_64+0x46/0x80
entry_SYSCALL_64_after_hwframe+0x44/0xae
</TASK>

WARNING: CPU: 3 PID: 2094 at net/ipv4/af_inet.c:155 inet_sock_destruct+0x13c/0x260
Call Trace:
<TASK>
__sk_destruct+0x24/0x1f0
sk_psock_destroy+0x19b/0x1c0
process_one_work+0x1b3/0x3c0
kthread+0xe6/0x110
ret_from_fork+0x22/0x30
</TASK>

Fixes: 604326b41a6f ("bpf, sockmap: convert to generic sk_msg interface")
Signed-off-by: Wang Yufen <wangyufen@huawei.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/bpf/20220304081145.2037182-3-wangyufen@huawei.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
net/core/skmsg.c | 17 +++++++++++++----
1 file changed, 13 insertions(+), 4 deletions(-)

diff --git a/net/core/skmsg.c b/net/core/skmsg.c
index 929a2b096b04..cc381165ea08 100644
--- a/net/core/skmsg.c
+++ b/net/core/skmsg.c
@@ -27,6 +27,7 @@ int sk_msg_alloc(struct sock *sk, struct sk_msg *msg, int len,
int elem_first_coalesce)
{
struct page_frag *pfrag = sk_page_frag(sk);
+ u32 osize = msg->sg.size;
int ret = 0;

len -= msg->sg.size;
@@ -35,13 +36,17 @@ int sk_msg_alloc(struct sock *sk, struct sk_msg *msg, int len,
u32 orig_offset;
int use, i;

- if (!sk_page_frag_refill(sk, pfrag))
- return -ENOMEM;
+ if (!sk_page_frag_refill(sk, pfrag)) {
+ ret = -ENOMEM;
+ goto msg_trim;
+ }

orig_offset = pfrag->offset;
use = min_t(int, len, pfrag->size - orig_offset);
- if (!sk_wmem_schedule(sk, use))
- return -ENOMEM;
+ if (!sk_wmem_schedule(sk, use)) {
+ ret = -ENOMEM;
+ goto msg_trim;
+ }

i = msg->sg.end;
sk_msg_iter_var_prev(i);
@@ -71,6 +76,10 @@ int sk_msg_alloc(struct sock *sk, struct sk_msg *msg, int len,
}

return ret;
+
+msg_trim:
+ sk_msg_trim(sk, msg, osize);
+ return ret;
}
EXPORT_SYMBOL_GPL(sk_msg_alloc);

--
2.34.1