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Wed, 03 Jun 2026 05:23:57 -0700 (PDT) Date: Wed, 3 Jun 2026 07:23:53 -0500 From: Corey Minyard To: Wentao Liang Cc: openipmi-developer@lists.sourceforge.net, linux-kernel@vger.kernel.org, stable@vger.kernel.org Subject: Re: [PATCH] ipmi: fix refcount leak in i_ipmi_request() Message-ID: Reply-To: corey@minyard.net References: <20260603120634.3758747-1-vulab@iscas.ac.cn> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260603120634.3758747-1-vulab@iscas.ac.cn> On Wed, Jun 03, 2026 at 12:06:34PM +0000, Wentao Liang wrote: > When a caller provides a `supplied_recv` message to i_ipmi_request(), > the function increments the user's `nr_msgs` reference count. If an > error occurs later, the out_err cleanup path only frees the recv_msg > if the function allocated it itself (i.e., !supplied_recv). In the > supplied_recv case the cleanup is skipped, leaving the reference count > elevated. The caller ipmi_request_supply_msgs() does not release the > supplied_recv on error, so the reference is permanently leaked. > > Fix this by explicitly reverting the reference count operations when a > supplied recv_msg with a valid user pointer is present in the error > path: decrement nr_msgs and drop the user's kref. This looks correct, it's in my next queue. Thanks, -corey > > Cc: stable@vger.kernel.org > Fixes: b52da4054ee0 ("ipmi: Rework user message limit handling") > Signed-off-by: Wentao Liang > --- > drivers/char/ipmi/ipmi_msghandler.c | 8 ++++++++ > 1 file changed, 8 insertions(+) > > diff --git a/drivers/char/ipmi/ipmi_msghandler.c b/drivers/char/ipmi/ipmi_msghandler.c > index 869ac87a4b6a..5b9d914cc7a9 100644 > --- a/drivers/char/ipmi/ipmi_msghandler.c > +++ b/drivers/char/ipmi/ipmi_msghandler.c > @@ -2347,6 +2347,10 @@ static int i_ipmi_request(struct ipmi_user *user, > if (smi_msg == NULL) { > if (!supplied_recv) > ipmi_free_recv_msg(recv_msg); > + else if (recv_msg->user) { > + atomic_dec(&recv_msg->user->nr_msgs); > + kref_put(&recv_msg->user->refcount, free_ipmi_user); > + } > return -ENOMEM; > } > } > @@ -2420,6 +2424,10 @@ static int i_ipmi_request(struct ipmi_user *user, > ipmi_free_smi_msg(smi_msg); > if (!supplied_recv) > ipmi_free_recv_msg(recv_msg); > + else if (recv_msg->user) { > + atomic_dec(&recv_msg->user->nr_msgs); > + kref_put(&recv_msg->user->refcount, free_ipmi_user); > + } > } > return rv; > } > -- > 2.34.1 >