2022-01-21 22:41:16

by Gustavo A. R. Silva

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Subject: [PATCH v2][next] ALSA: usb-audio: scarlett2: Use struct_size() helper in scarlett2_usb()

Make use of the struct_size() helper instead of an open-coded version,
in order to avoid any potential type mistakes or integer overflows that,
in the worst scenario, could lead to heap overflows.

Also, address the following sparse warnings:
sound/usb/mixer_scarlett_gen2.c:1064:28: warning: using sizeof on a flexible structure
sound/usb/mixer_scarlett_gen2.c:1065:29: warning: using sizeof on a flexible structure

Link: https://github.com/KSPP/linux/issues/174
Signed-off-by: Gustavo A. R. Silva <[email protected]>
---
Changes in v2:
- Use correct format specifier %zu for type size_t argument.

sound/usb/mixer_scarlett_gen2.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/sound/usb/mixer_scarlett_gen2.c b/sound/usb/mixer_scarlett_gen2.c
index 53ebabf42472..7ff8a4817c67 100644
--- a/sound/usb/mixer_scarlett_gen2.c
+++ b/sound/usb/mixer_scarlett_gen2.c
@@ -1061,9 +1061,9 @@ static int scarlett2_usb(
{
struct scarlett2_data *private = mixer->private_data;
struct usb_device *dev = mixer->chip->dev;
- u16 req_buf_size = sizeof(struct scarlett2_usb_packet) + req_size;
- u16 resp_buf_size = sizeof(struct scarlett2_usb_packet) + resp_size;
struct scarlett2_usb_packet *req, *resp = NULL;
+ size_t req_buf_size = struct_size(req, data, req_size);
+ size_t resp_buf_size = struct_size(resp, data, resp_size);
int err;

req = kmalloc(req_buf_size, GFP_KERNEL);
@@ -1111,7 +1111,7 @@ static int scarlett2_usb(
usb_audio_err(
mixer->chip,
"Scarlett Gen 2/3 USB response result cmd %x was %d "
- "expected %d\n",
+ "expected %zu\n",
cmd, err, resp_buf_size);
err = -EINVAL;
goto unlock;
--
2.27.0


2022-01-22 00:24:16

by Kees Cook

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Subject: Re: [PATCH v2][next] ALSA: usb-audio: scarlett2: Use struct_size() helper in scarlett2_usb()

On Thu, Jan 20, 2022 at 03:16:00PM -0600, Gustavo A. R. Silva wrote:
> Make use of the struct_size() helper instead of an open-coded version,
> in order to avoid any potential type mistakes or integer overflows that,
> in the worst scenario, could lead to heap overflows.
>
> Also, address the following sparse warnings:
> sound/usb/mixer_scarlett_gen2.c:1064:28: warning: using sizeof on a flexible structure
> sound/usb/mixer_scarlett_gen2.c:1065:29: warning: using sizeof on a flexible structure
>
> Link: https://github.com/KSPP/linux/issues/174
> Signed-off-by: Gustavo A. R. Silva <[email protected]>

Looks good to me!

Reviewed-by: Kees Cook <[email protected]>

> ---
> Changes in v2:
> - Use correct format specifier %zu for type size_t argument.
>
> sound/usb/mixer_scarlett_gen2.c | 6 +++---
> 1 file changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/sound/usb/mixer_scarlett_gen2.c b/sound/usb/mixer_scarlett_gen2.c
> index 53ebabf42472..7ff8a4817c67 100644
> --- a/sound/usb/mixer_scarlett_gen2.c
> +++ b/sound/usb/mixer_scarlett_gen2.c
> @@ -1061,9 +1061,9 @@ static int scarlett2_usb(
> {
> struct scarlett2_data *private = mixer->private_data;
> struct usb_device *dev = mixer->chip->dev;
> - u16 req_buf_size = sizeof(struct scarlett2_usb_packet) + req_size;
> - u16 resp_buf_size = sizeof(struct scarlett2_usb_packet) + resp_size;
> struct scarlett2_usb_packet *req, *resp = NULL;
> + size_t req_buf_size = struct_size(req, data, req_size);
> + size_t resp_buf_size = struct_size(resp, data, resp_size);
> int err;
>
> req = kmalloc(req_buf_size, GFP_KERNEL);
> @@ -1111,7 +1111,7 @@ static int scarlett2_usb(
> usb_audio_err(
> mixer->chip,
> "Scarlett Gen 2/3 USB response result cmd %x was %d "
> - "expected %d\n",
> + "expected %zu\n",
> cmd, err, resp_buf_size);
> err = -EINVAL;
> goto unlock;
> --
> 2.27.0
>

--
Kees Cook

2022-01-25 20:03:37

by Takashi Iwai

[permalink] [raw]
Subject: Re: [PATCH v2][next] ALSA: usb-audio: scarlett2: Use struct_size() helper in scarlett2_usb()

On Thu, 20 Jan 2022 22:16:00 +0100,
Gustavo A. R. Silva wrote:
>
> Make use of the struct_size() helper instead of an open-coded version,
> in order to avoid any potential type mistakes or integer overflows that,
> in the worst scenario, could lead to heap overflows.
>
> Also, address the following sparse warnings:
> sound/usb/mixer_scarlett_gen2.c:1064:28: warning: using sizeof on a flexible structure
> sound/usb/mixer_scarlett_gen2.c:1065:29: warning: using sizeof on a flexible structure
>
> Link: https://github.com/KSPP/linux/issues/174
> Signed-off-by: Gustavo A. R. Silva <[email protected]>
> ---
> Changes in v2:
> - Use correct format specifier %zu for type size_t argument.

Applied now. Thanks.


Takashi