summaryrefslogtreecommitdiff
path: root/include/net/inet_connection_sock.h
diff options
context:
space:
mode:
authorEric Dumazet <edumazet@google.com>2024-03-22 16:57:32 +0300
committerJakub Kicinski <kuba@kernel.org>2024-03-26 05:51:57 +0300
commit151c9c724d05d5b0dd8acd3e11cb69ef1f2dbada (patch)
tree2898f08d52d867b9e185380de9ce66d961469058 /include/net/inet_connection_sock.h
parentb11c81731c810efe592e510bb0110e0db6877419 (diff)
downloadlinux-151c9c724d05d5b0dd8acd3e11cb69ef1f2dbada.tar.xz
tcp: properly terminate timers for kernel sockets
We had various syzbot reports about tcp timers firing after the corresponding netns has been dismantled. Fortunately Josef Bacik could trigger the issue more often, and could test a patch I wrote two years ago. When TCP sockets are closed, we call inet_csk_clear_xmit_timers() to 'stop' the timers. inet_csk_clear_xmit_timers() can be called from any context, including when socket lock is held. This is the reason it uses sk_stop_timer(), aka del_timer(). This means that ongoing timers might finish much later. For user sockets, this is fine because each running timer holds a reference on the socket, and the user socket holds a reference on the netns. For kernel sockets, we risk that the netns is freed before timer can complete, because kernel sockets do not hold reference on the netns. This patch adds inet_csk_clear_xmit_timers_sync() function that using sk_stop_timer_sync() to make sure all timers are terminated before the kernel socket is released. Modules using kernel sockets close them in their netns exit() handler. Also add sock_not_owned_by_me() helper to get LOCKDEP support : inet_csk_clear_xmit_timers_sync() must not be called while socket lock is held. It is very possible we can revert in the future commit 3a58f13a881e ("net: rds: acquire refcount on TCP sockets") which attempted to solve the issue in rds only. (net/smc/af_smc.c and net/mptcp/subflow.c have similar code) We probably can remove the check_net() tests from tcp_out_of_resources() and __tcp_close() in the future. Reported-by: Josef Bacik <josef@toxicpanda.com> Closes: https://lore.kernel.org/netdev/20240314210740.GA2823176@perftesting/ Fixes: 26abe14379f8 ("net: Modify sk_alloc to not reference count the netns of kernel sockets.") Fixes: 8a68173691f0 ("net: sk_clone_lock() should only do get_net() if the parent is not a kernel socket") Link: https://lore.kernel.org/bpf/CANn89i+484ffqb93aQm1N-tjxxvb3WDKX0EbD7318RwRgsatjw@mail.gmail.com/ Signed-off-by: Eric Dumazet <edumazet@google.com> Tested-by: Josef Bacik <josef@toxicpanda.com> Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Link: https://lore.kernel.org/r/20240322135732.1535772-1-edumazet@google.com Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Diffstat (limited to 'include/net/inet_connection_sock.h')
-rw-r--r--include/net/inet_connection_sock.h1
1 files changed, 1 insertions, 0 deletions
diff --git a/include/net/inet_connection_sock.h b/include/net/inet_connection_sock.h
index 9ab4bf704e86..ccf171f7eb60 100644
--- a/include/net/inet_connection_sock.h
+++ b/include/net/inet_connection_sock.h
@@ -175,6 +175,7 @@ void inet_csk_init_xmit_timers(struct sock *sk,
void (*delack_handler)(struct timer_list *),
void (*keepalive_handler)(struct timer_list *));
void inet_csk_clear_xmit_timers(struct sock *sk);
+void inet_csk_clear_xmit_timers_sync(struct sock *sk);
static inline void inet_csk_schedule_ack(struct sock *sk)
{