linux-kernel - [PATCH RFC 1/1] ipmi: Fix double list

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Message-ID: <20260205144739.116409-2-k@mgml.me>
Date: Thu,  5 Feb 2026 23:47:39 +0900
From: Kenta Akagi <k@...l.me>
To: Corey Minyard <corey@...yard.net>
Cc: openipmi-developer@...ts.sourceforge.net, linux-kernel@...r.kernel.org,
        stable@...r.kernel.org, Kenta Akagi <k@...l.me>
Subject: [PATCH RFC 1/1] ipmi: Fix double list_add when sender returns an error

Since commit 9cf93a8fa951 ("ipmi: Allow an SMI sender to return an
error"), when the BMC does not respond, the sender returns an error, and
smi_work goes to restart.

However, curr_msg is not cleared during restart,
which results in a panic due to a double add to the list after restart.

[164050.860241] list_add double add: new=ffff8a5833cd0000, prev=ffff8a5833cd0000, next=ffff8a387b2491b0.
[164050.869744] ------------[ cut here ]------------
[164050.874698] kernel BUG at lib/list_debug.c:35!
[164050.879435] Oops: invalid opcode: 0000 [#1] SMP NOPTI
[164050.884742] CPU: 5 UID: 0 PID: 99228 Comm: kworker/5:2 Kdump: loaded Tainted: G S          E       6.18.7-20260127.el9.x86_64 #1 PREEMPT(voluntary)
[164050.899481] Tainted: [S]=CPU_OUT_OF_SPEC, [E]=UNSIGNED_MODULE
[164050.905470] Hardware name: Dell Inc. PowerEdge R640/0X45NX, BIOS 2.15.1 06/15/2022
[164050.913285] Workqueue: events smi_work [ipmi_msghandler]
[164050.918865] RIP: 0010:__list_add_valid_or_report+0xb6/0xc0
[164050.924609] Code: c7 e8 b1 c3 89 48 8b 16 48 89 f1 4c 89 e6 e8 e1 16 a9 ff 0f 0b 48 89 f2 4c 89 e1 48 89 fe 48 c7 c7 40 b2 c3 89 e8 ca 16 a9 ff <0f> 0b 0f 1f 84 00 00 00 00 00 90 90 90 90 90 90 90 90 90 90 90 90
[164050.943787] RSP: 0018:ffffceacac91fdc0 EFLAGS: 00010246
[164050.949271] RAX: 0000000000000058 RBX: ffff8a5833cd0000 RCX: 0000000000000000
[164050.956665] RDX: 0000000000000000 RSI: 0000000000000001 RDI: ffff8a773f89c1c0
[164050.964054] RBP: ffff8a5833cd0000 R08: 0000000000000000 R09: ffffceacac91fc78
[164050.971441] R10: ffffceacac91fc70 R11: ffffffff8a7e10c8 R12: ffff8a387b2491b0
[164050.978837] R13: 0000000000000000 R14: ffff8a387b249190 R15: ffff8a387b2491b0
[164050.986229] FS:  0000000000000000(0000) GS:ffff8a77b459d000(0000) knlGS:0000000000000000
[164050.994581] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[164051.000597] CR2: 00007ff95841be6c CR3: 000000063b022001 CR4: 00000000007726f0
[164051.007997] PKRU: 55555554
[164051.010970] Call Trace:
[164051.013690]  <TASK>
[164051.016055]  ? mutex_lock+0xe/0x30
[164051.019724]  deliver_response+0x59/0x100 [ipmi_msghandler]
[164051.025495]  smi_work+0xa0/0x370 [ipmi_msghandler]
[164051.030563]  process_one_work+0x19d/0x3d0
[164051.034844]  worker_thread+0x23e/0x360
[164051.038873]  ? __pfx_worker_thread+0x10/0x10
[164051.043423]  kthread+0xfb/0x230
[164051.046850]  ? __pfx_kthread+0x10/0x10
[164051.050872]  ? __pfx_kthread+0x10/0x10
[164051.054894]  ret_from_fork+0xe9/0x100
[164051.058826]  ? __pfx_kthread+0x10/0x10
[164051.062852]  ret_from_fork_asm+0x1a/0x30
[164051.067065]  </TASK>

This commit ensures that the next message is dequeued from the queue
upon restart.

Cc: stable@...r.kernel.org
Fixes: 9cf93a8fa951 ("ipmi: Allow an SMI sender to return an error")
Signed-off-by: Kenta Akagi <k@...l.me>
---
 drivers/char/ipmi/ipmi_msghandler.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/char/ipmi/ipmi_msghandler.c b/drivers/char/ipmi/ipmi_msghandler.c
index 3f48fc6ab596..17242b3cf53d 100644
--- a/drivers/char/ipmi/ipmi_msghandler.c
+++ b/drivers/char/ipmi/ipmi_msghandler.c
@@ -4814,7 +4814,7 @@ static void smi_work(struct work_struct *t)
 	unsigned long flags = 0; /* keep us warning-free. */
 	struct ipmi_smi *intf = from_work(intf, t, smi_work);
 	int run_to_completion = READ_ONCE(intf->run_to_completion);
-	struct ipmi_smi_msg *newmsg = NULL;
+	struct ipmi_smi_msg *newmsg;
 	struct ipmi_recv_msg *msg, *msg2;
 	int cc;
 
@@ -4826,6 +4826,7 @@ static void smi_work(struct work_struct *t)
 	 * message delivery.
 	 */
 restart:
+	newmsg = NULL;
 	if (!run_to_completion)
 		spin_lock_irqsave(&intf->xmit_msgs_lock, flags);
 	if (intf->curr_msg == NULL && !intf->in_shutdown) {
@@ -4854,6 +4855,7 @@ static void smi_work(struct work_struct *t)
 						     newmsg->recv_msg, cc);
 			else
 				ipmi_free_smi_msg(newmsg);
+			intf->curr_msg = NULL;
 			goto restart;
 		}
 	}
-- 
2.50.1