Commit 97d9fba9 authored by Breno Leitao's avatar Breno Leitao Committed by Jakub Kicinski
Browse files

net: netconsole: Disable target before netpoll cleanup 



Currently, netconsole cleans up the netpoll structure before disabling
the target. This approach can lead to race conditions, as message
senders (write_ext_msg() and write_msg()) check if the target is
enabled before using netpoll. The sender can validate that the target is
enabled, but, the netpoll might be de-allocated already, causing
undesired behaviours.

This patch reverses the order of operations:
1. Disable the target
2. Clean up the netpoll structure

This change eliminates the potential race condition, ensuring that
no messages are sent through a partially cleaned-up netpoll structure.

Fixes: 2382b15b ("netconsole: take care of NETDEV_UNREGISTER event")
Cc: stable@vger.kernel.org
Signed-off-by: default avatarBreno Leitao <leitao@debian.org>
Reviewed-by: default avatarEric Dumazet <edumazet@google.com>
Link: https://patch.msgid.link/20240712143415.1141039-1-leitao@debian.org


Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
parent d657f5c7

drivers/net/netconsole.c

+1 −1
Original line number Diff line number Diff line
@@ -974,6 +974,7 @@ static int netconsole_netdev_event(struct notifier_block *this, 
				/* rtnl_lock already held

				 * we might sleep in __netpoll_cleanup()

				 */

				nt->enabled = false;

				spin_unlock_irqrestore(&target_list_lock, flags);



				__netpoll_cleanup(&nt->np);
@@ -981,7 +982,6 @@ static int netconsole_netdev_event(struct notifier_block *this, 
				spin_lock_irqsave(&target_list_lock, flags);

				netdev_put(nt->np.dev, &nt->np.dev_tracker);

				nt->np.dev = NULL;

				nt->enabled = false;

				stopped = true;

				netconsole_target_put(nt);

				goto restart;