[PATCH v2] media: meson: vdec: Fix memory leak in error path of vdec_open

[PATCH v2] media: meson: vdec: Fix memory leak in error path of vdec_open

[Anand Moon]

The vdec_open and vdec_close functions in the Meson VDEC driver failed
to release several resources, leading to memory leaks and potential
use-after-free scenarios.

This patch addresses:
- Missing v4l2_ctrl_handler_free() in both the close path and error
  exit of the open path, preventing control memory leaks.
- A leak of the M2M context if vdec_init_ctrls() failed.

The error labels in vdec_open() have been reordered to ensure a proper
Last-In-First-Out (LIFO) teardown of all initialized resources.

This was identified via kmemleak:
unreferenced object 0xffff0000205d6878 (size 8):
  comm "v4l_id", pid 5289, jiffies 4294938580
  hex dump (first 8 bytes):
    40 d2 49 18 00 00 ff ff                          @.I.....
  backtrace (crc d3204599):
    kmemleak_alloc+0xc8/0xf0
    __kvmalloc_node_noprof+0x60c/0x850
    v4l2_ctrl_handler_init_class+0x1b4/0x2e8 [videodev]
    vdec_open+0x1f4/0x788 [meson_vdec]
    v4l2_open+0x144/0x460 [videodev]
    chrdev_open+0x1ac/0x500
    do_dentry_open+0x3f0/0xfe8
    vfs_open+0x68/0x320
    do_open+0x2d8/0x9a8
    path_openat+0x1d0/0x4f0
    do_filp_open+0x190/0x380
    do_sys_openat2+0xf8/0x1b0
    __arm64_sys_openat+0x13c/0x1e8
    invoke_syscall+0xdc/0x268
    el0_svc_common.constprop.0+0x178/0x258
    do_el0_svc+0x4c/0x70

Cc: Nicolas Dufresne <nicolas@ndufresne.ca>
Fixes: 3e7f51bd9607 ("media: meson: add v4l2 m2m video decoder driver")
Signed-off-by: Anand Moon <linux.amoon@gmail.com>
---
v1: https://lore.kernel.org/all/20260304100557.126488-1-linux.amoon@gmail.com/
   tried to address the issue reported by Nicolas
   improve the commit message.
---
 drivers/staging/media/meson/vdec/vdec.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/drivers/staging/media/meson/vdec/vdec.c b/drivers/staging/media/meson/vdec/vdec.c
index 4b77ec1af5a76..3a5e4ebe0b34c 100644
--- a/drivers/staging/media/meson/vdec/vdec.c
+++ b/drivers/staging/media/meson/vdec/vdec.c
@@ -877,7 +877,7 @@ static int vdec_open(struct file *file)
 	if (IS_ERR(sess->m2m_dev)) {
 		dev_err(dev, "Fail to v4l2_m2m_init\n");
 		ret = PTR_ERR(sess->m2m_dev);
-		goto err_free_sess;
+		goto err_m2m_release;
 	}
 
 	sess->m2m_ctx = v4l2_m2m_ctx_init(sess->m2m_dev, sess, m2m_queue_init);
@@ -889,7 +889,7 @@ static int vdec_open(struct file *file)
 
 	ret = vdec_init_ctrls(sess);
 	if (ret)
-		goto err_m2m_release;
+		goto err_m2m_ctx_release;
 
 	sess->pixfmt_cap = formats[0].pixfmts_cap[0];
 	sess->fmt_out = &formats[0];
@@ -913,9 +913,11 @@ static int vdec_open(struct file *file)
 
 	return 0;
 
+err_m2m_ctx_release:
+	v4l2_m2m_ctx_release(sess->m2m_ctx);
 err_m2m_release:
 	v4l2_m2m_release(sess->m2m_dev);
-err_free_sess:
+	v4l2_ctrl_handler_free(&sess->ctrl_handler);
 	kfree(sess);
 	return ret;
 }
@@ -926,6 +928,7 @@ static int vdec_close(struct file *file)
 
 	v4l2_m2m_ctx_release(sess->m2m_ctx);
 	v4l2_m2m_release(sess->m2m_dev);
+	v4l2_ctrl_handler_free(&sess->ctrl_handler);
 	v4l2_fh_del(&sess->fh, file);
 	v4l2_fh_exit(&sess->fh);
 

base-commit: a0c83177734ab98623795e1ba2cf4b72c23de5e7
-- 
2.50.1