linux-kernel - [PATCH] drm: Fix possible memleak in drm_client_modeset

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Message-ID: <20211022012623.97631-1-heying24@huawei.com>
Date:   Thu, 21 Oct 2021 21:26:23 -0400
From:   He Ying <heying24@...wei.com>
To:     <maarten.lankhorst@...ux.intel.com>, <mripard@...nel.org>,
        <tzimmermann@...e.de>, <airlied@...ux.ie>, <daniel@...ll.ch>
CC:     <dri-devel@...ts.freedesktop.org>, <linux-kernel@...r.kernel.org>
Subject: [PATCH] drm: Fix possible memleak in drm_client_modeset_probe

I got memory leak as follows when doing fault injection test:

WARNING: CPU: 0 PID: 1214 at drm_mode_config_cleanup+0x689/0x890 [drm]
RIP: 0010:drm_mode_config_cleanup+0x689/0x890 [drm]
Call Trace:
 ? tracer_hardirqs_on+0x33/0x520
 ? drm_mode_config_reset+0x3f0/0x3f0 [drm]
 ? trace_event_raw_event_rcu_torture_read+0x2c0/0x2c0
 ? __sanitizer_cov_trace_pc+0x1d/0x50
 ? call_rcu+0x489/0x15e0
 ? trace_hardirqs_on+0x63/0x2d0
 ? write_comp_data+0x2a/0x90
 ? drm_mode_config_cleanup+0x890/0x890 [drm]
 drm_managed_release+0x1fa/0x4f0 [drm]
 drm_dev_release+0x72/0xb0 [drm]
 devm_drm_dev_init_release+0x81/0xa0 [drm]
 release_nodes+0xba/0x3b0
 ...
 entry_SYSCALL_64_after_hwframe+0x44/0xae

and then an error message:

[drm:drm_mode_config_cleanup [drm]] *ERROR* connector SPI-1 leaked!

When krealloc() in drm_client_modeset_probe() fails, it
goes to the label 'free_connectors'. However, krealloc()
is between drm_connector_list_iter_begin() and *_end().
Going to the label directly is not a good idea. Because
iter->conn is not cleaned up if so. Fix the problem by
going to the label outside drm_connector_list_iter_end().

Signed-off-by: He Ying <heying24@...wei.com>
---
 drivers/gpu/drm/drm_client_modeset.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/drm_client_modeset.c b/drivers/gpu/drm/drm_client_modeset.c
index ced09c7c06f9..7ac88ae93f38 100644
--- a/drivers/gpu/drm/drm_client_modeset.c
+++ b/drivers/gpu/drm/drm_client_modeset.c
@@ -789,7 +789,7 @@ int drm_client_modeset_probe(struct drm_client_dev *client, unsigned int width,
 		tmp = krealloc(connectors, (connector_count + 1) * sizeof(*connectors), GFP_KERNEL);
 		if (!tmp) {
 			ret = -ENOMEM;
-			goto free_connectors;
+			break;
 		}

 		connectors = tmp;
@@ -798,6 +798,9 @@ int drm_client_modeset_probe(struct drm_client_dev *client, unsigned int width,
 	}
 	drm_connector_list_iter_end(&conn_iter);

+	if (ret)
+		goto free_connectors;
+
 	if (!connector_count)
 		return 0;

-- 
2.17.1