2022-09-12 17:09:33

by Nam Cao

Subject: [PATCH] staging: vt6655: fix some erroneous memory clean-up loops

In some initialization functions of this driver, memory is allocated with
'i' acting as an index variable and increasing from 0. The commit in
"Fixes" introduces some clean-up codes in case of allocation failure,
which free memory in reverse order with 'i' decreasing to 0. However,
there are some problems:
- The case i=0 is left out. Thus memory is leaked.
- In case memory allocation fails right from the start, the memory
freeing loops will start with i=-1 and invalid memory locations will
be accessed.

One of these loops has been fixed in commit c8ff91535880 ("staging:
vt6655: fix potential memory leak"). Fix the remaining erroneous loops.

Link: https://lore.kernel.org/linux-staging/Yx9H1zSpxmNqx6Xc@kadam/
Reported-by: Dan Carpenter <[email protected]>
Fixes: 5341ee0adb17 ("staging: vt6655: check for memory allocation failures")
Signed-off-by: Nam Cao <[email protected]>
---
drivers/staging/vt6655/device_main.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/staging/vt6655/device_main.c b/drivers/staging/vt6655/device_main.c
index 04d737012cef..56c3cf3ba53d 100644
--- a/drivers/staging/vt6655/device_main.c
+++ b/drivers/staging/vt6655/device_main.c
@@ -631,7 +631,7 @@ static int device_init_rd0_ring(struct vnt_private *priv)
kfree(desc->rd_info);

err_free_desc:
- while (--i) {
+ while (i--) {
desc = &priv->aRD0Ring[i];
device_free_rx_buf(priv, desc);
kfree(desc->rd_info);
@@ -677,7 +677,7 @@ static int device_init_rd1_ring(struct vnt_private *priv)
kfree(desc->rd_info);

err_free_desc:
- while (--i) {
+ while (i--) {
desc = &priv->aRD1Ring[i];
device_free_rx_buf(priv, desc);
kfree(desc->rd_info);
@@ -782,7 +782,7 @@ static int device_init_td1_ring(struct vnt_private *priv)
return 0;

err_free_desc:
- while (--i) {
+ while (i--) {
desc = &priv->apTD1Rings[i];
kfree(desc->td_info);
}
--
2.25.1

2022-09-12 19:28:47

by Philipp Hortmann

Subject: Re: [PATCH] staging: vt6655: fix some erroneous memory clean-up loops

On 9/12/22 19:04, Nam Cao wrote:
> In some initialization functions of this driver, memory is allocated with
> 'i' acting as an index variable and increasing from 0. The commit in
> "Fixes" introduces some clean-up codes in case of allocation failure,
> which free memory in reverse order with 'i' decreasing to 0. However,
> there are some problems:
> - The case i=0 is left out. Thus memory is leaked.
> - In case memory allocation fails right from the start, the memory
> freeing loops will start with i=-1 and invalid memory locations will
> be accessed.
>
> One of these loops has been fixed in commit c8ff91535880 ("staging:
> vt6655: fix potential memory leak"). Fix the remaining erroneous loops.
>
> Link: https://lore.kernel.org/linux-staging/Yx9H1zSpxmNqx6Xc@kadam/
> Reported-by: Dan Carpenter <[email protected]>
> Fixes: 5341ee0adb17 ("staging: vt6655: check for memory allocation failures")
> Signed-off-by: Nam Cao <[email protected]>
> ---
> drivers/staging/vt6655/device_main.c | 6 +++---
> 1 file changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/staging/vt6655/device_main.c b/drivers/staging/vt6655/device_main.c
> index 04d737012cef..56c3cf3ba53d 100644
> --- a/drivers/staging/vt6655/device_main.c
> +++ b/drivers/staging/vt6655/device_main.c
> @@ -631,7 +631,7 @@ static int device_init_rd0_ring(struct vnt_private *priv)
> kfree(desc->rd_info);
>
> err_free_desc:
> - while (--i) {
> + while (i--) {
> desc = &priv->aRD0Ring[i];
> device_free_rx_buf(priv, desc);
> kfree(desc->rd_info);
> @@ -677,7 +677,7 @@ static int device_init_rd1_ring(struct vnt_private *priv)
> kfree(desc->rd_info);
>
> err_free_desc:
> - while (--i) {
> + while (i--) {
> desc = &priv->aRD1Ring[i];
> device_free_rx_buf(priv, desc);
> kfree(desc->rd_info);
> @@ -782,7 +782,7 @@ static int device_init_td1_ring(struct vnt_private *priv)
> return 0;
>
> err_free_desc:
> - while (--i) {
> + while (i--) {
> desc = &priv->apTD1Rings[i];
> kfree(desc->td_info);
> }

Tested-by: Philipp Hortmann <[email protected]>