From c08ec55617cb9674a060a3392ea08391ab2a4f74 Mon Sep 17 00:00:00 2001 From: Corey Minyard Date: Tue, 27 Jan 2026 07:22:35 -0600 Subject: [PATCH] ipmi: Fix use-after-free and list corruption on sender error commit 594c11d0e1d445f580898a2b8c850f2e3f099368 upstream. The analysis from Breno: When the SMI sender returns an error, smi_work() delivers an error response but then jumps back to restart without cleaning up properly: 1. intf->curr_msg is not cleared, so no new message is pulled 2. newmsg still points to the message, causing sender() to be called again with the same message 3. If sender() fails again, deliver_err_response() is called with the same recv_msg that was already queued for delivery This causes list_add corruption ("list_add double add") because the recv_msg is added to the user_msgs list twice. Subsequently, the corrupted list leads to use-after-free when the memory is freed and reused, and eventually a NULL pointer dereference when accessing recv_msg->done. The buggy sequence: sender() fails -> deliver_err_response(recv_msg) // recv_msg queued for delivery -> goto restart // curr_msg not cleared! sender() fails again (same message!) -> deliver_err_response(recv_msg) // tries to queue same recv_msg -> LIST CORRUPTION Fix this by freeing the message and setting it to NULL on a send error. Also, always free the newmsg on a send error, otherwise it will leak. Reported-by: Breno Leitao Closes: https://lore.kernel.org/lkml/20260127-ipmi-v1-0-ba5cc90f516f@debian.org/ Fixes: 9cf93a8fa9513 ("ipmi: Allow an SMI sender to return an error") Cc: stable@vger.kernel.org # 4.18 Reviewed-by: Breno Leitao Signed-off-by: Corey Minyard Signed-off-by: Breno Leitao Signed-off-by: Greg Kroah-Hartman --- drivers/char/ipmi/ipmi_msghandler.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-) diff --git a/drivers/char/ipmi/ipmi_msghandler.c b/drivers/char/ipmi/ipmi_msghandler.c index 0a886399f9da..5ed8e95589fb 100644 --- a/drivers/char/ipmi/ipmi_msghandler.c +++ b/drivers/char/ipmi/ipmi_msghandler.c @@ -4848,8 +4848,15 @@ restart: if (newmsg->recv_msg) deliver_err_response(intf, newmsg->recv_msg, cc); - else - ipmi_free_smi_msg(newmsg); + if (!run_to_completion) + spin_lock_irqsave(&intf->xmit_msgs_lock, + flags); + intf->curr_msg = NULL; + if (!run_to_completion) + spin_unlock_irqrestore(&intf->xmit_msgs_lock, + flags); + ipmi_free_smi_msg(newmsg); + newmsg = NULL; goto restart; } }