Re: [PATCH] media: em28xx: Fix possible memory leak of em28xx struct

From: Shuah Khan
Date: Mon May 03 2021 - 16:06:16 EST

Hi Igor,

On 5/3/21 11:37 AM, Igor Matheus Andrade Torrente wrote:
The em28xx struct kref isn't being decreased after an error in the
em28xx_ir_init, leading to a possible memory leak.

A kref_put is added to the error handler code.

Signed-off-by: Igor Matheus Andrade Torrente <igormtorrente@xxxxxxxxx>
drivers/media/usb/em28xx/em28xx-input.c | 7 +++++--
1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/drivers/media/usb/em28xx/em28xx-input.c b/drivers/media/usb/em28xx/em28xx-input.c
index 5aa15a7a49de..b89527014cad 100644
--- a/drivers/media/usb/em28xx/em28xx-input.c
+++ b/drivers/media/usb/em28xx/em28xx-input.c
@@ -720,7 +720,8 @@ static int em28xx_ir_init(struct em28xx *dev)
dev->board.has_ir_i2c = 0;
"No i2c IR remote control device found.\n");
- return -ENODEV;
+ err = -ENODEV;
+ goto ref_put;

This doesn't look right. em28xx_init_buttons() is already happened and
em28xx_shutdown_buttons() needs to be done from fini. fini needs to run
with this ref. If ref is released here, device might be released before
em28xx_shutdown_buttons() can run leading to potential use-after-free

@@ -735,7 +736,7 @@ static int em28xx_ir_init(struct em28xx *dev)
ir = kzalloc(sizeof(*ir), GFP_KERNEL);
if (!ir)
- return -ENOMEM;
+ goto ref_put;

This doesn't look right. Same comment as above. fini accounts for null


/* skip detach on non attached boards */
if (!ir)
goto ref_put;

rc = rc_allocate_device(RC_DRIVER_SCANCODE);
if (!rc)
goto error;
@@ -839,6 +840,8 @@ static int em28xx_ir_init(struct em28xx *dev)
dev->ir = NULL;
+ kref_put(&dev->ref, em28xx_free_device);
return err;

-- Shuah