* [PATCH] USB: serial: mos7720: improve handling of a kmalloc failure in read_mos_reg()
@ 2021-01-11 22:09 trix
2021-01-11 22:31 ` Nathan Chancellor
2021-01-12 8:57 ` Johan Hovold
0 siblings, 2 replies; 3+ messages in thread
From: trix @ 2021-01-11 22:09 UTC (permalink / raw)
To: johan, gregkh, natechancellor, ndesaulniers
Cc: linux-usb, linux-kernel, clang-built-linux, Tom Rix
From: Tom Rix <trix@redhat.com>
clang static analysis reports this problem
mos7720.c:352:2: warning: Undefined or garbage value returned to caller
return d;
^~~~~~~~
In the parport_mos7715_read_data()'s call to read_mos_reg(), 'd' is
only set after the alloc block.
buf = kmalloc(1, GFP_KERNEL);
if (!buf)
return -ENOMEM;
Although the problem is reported in parport_most7715_read_data(),
none of the callee's of read_mos_reg() check the return status.
So move the clearing of data to before the malloc.
Fixes: 0d130367abf5 ("USB: serial: mos7720: fix control-message error handling")
Signed-off-by: Tom Rix <trix@redhat.com>
---
drivers/usb/serial/mos7720.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/usb/serial/mos7720.c b/drivers/usb/serial/mos7720.c
index 41ee2984a0df..23e8162c768b 100644
--- a/drivers/usb/serial/mos7720.c
+++ b/drivers/usb/serial/mos7720.c
@@ -214,6 +214,7 @@ static int read_mos_reg(struct usb_serial *serial, unsigned int serial_portnum,
u8 *buf;
int status;
+ *data = 0;
buf = kmalloc(1, GFP_KERNEL);
if (!buf)
return -ENOMEM;
@@ -227,7 +228,6 @@ static int read_mos_reg(struct usb_serial *serial, unsigned int serial_portnum,
"mos7720: usb_control_msg() failed: %d\n", status);
if (status >= 0)
status = -EIO;
- *data = 0;
}
kfree(buf);
--
2.27.0
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH] USB: serial: mos7720: improve handling of a kmalloc failure in read_mos_reg()
2021-01-11 22:09 [PATCH] USB: serial: mos7720: improve handling of a kmalloc failure in read_mos_reg() trix
@ 2021-01-11 22:31 ` Nathan Chancellor
2021-01-12 8:57 ` Johan Hovold
1 sibling, 0 replies; 3+ messages in thread
From: Nathan Chancellor @ 2021-01-11 22:31 UTC (permalink / raw)
To: trix
Cc: johan, gregkh, ndesaulniers, linux-usb, linux-kernel, clang-built-linux
On Mon, Jan 11, 2021 at 02:09:04PM -0800, trix@redhat.com wrote:
> From: Tom Rix <trix@redhat.com>
>
> clang static analysis reports this problem
>
> mos7720.c:352:2: warning: Undefined or garbage value returned to caller
> return d;
> ^~~~~~~~
>
> In the parport_mos7715_read_data()'s call to read_mos_reg(), 'd' is
> only set after the alloc block.
>
> buf = kmalloc(1, GFP_KERNEL);
> if (!buf)
> return -ENOMEM;
>
> Although the problem is reported in parport_most7715_read_data(),
> none of the callee's of read_mos_reg() check the return status.
>
> So move the clearing of data to before the malloc.
>
> Fixes: 0d130367abf5 ("USB: serial: mos7720: fix control-message error handling")
> Signed-off-by: Tom Rix <trix@redhat.com>
Reviewed-by: Nathan Chancellor <natechancellor@gmail.com>
> ---
> drivers/usb/serial/mos7720.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/usb/serial/mos7720.c b/drivers/usb/serial/mos7720.c
> index 41ee2984a0df..23e8162c768b 100644
> --- a/drivers/usb/serial/mos7720.c
> +++ b/drivers/usb/serial/mos7720.c
> @@ -214,6 +214,7 @@ static int read_mos_reg(struct usb_serial *serial, unsigned int serial_portnum,
> u8 *buf;
> int status;
>
> + *data = 0;
> buf = kmalloc(1, GFP_KERNEL);
> if (!buf)
> return -ENOMEM;
> @@ -227,7 +228,6 @@ static int read_mos_reg(struct usb_serial *serial, unsigned int serial_portnum,
> "mos7720: usb_control_msg() failed: %d\n", status);
> if (status >= 0)
> status = -EIO;
> - *data = 0;
> }
>
> kfree(buf);
> --
> 2.27.0
>
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] USB: serial: mos7720: improve handling of a kmalloc failure in read_mos_reg()
2021-01-11 22:09 [PATCH] USB: serial: mos7720: improve handling of a kmalloc failure in read_mos_reg() trix
2021-01-11 22:31 ` Nathan Chancellor
@ 2021-01-12 8:57 ` Johan Hovold
1 sibling, 0 replies; 3+ messages in thread
From: Johan Hovold @ 2021-01-12 8:57 UTC (permalink / raw)
To: trix
Cc: johan, gregkh, natechancellor, ndesaulniers, linux-usb,
linux-kernel, clang-built-linux
On Mon, Jan 11, 2021 at 02:09:04PM -0800, trix@redhat.com wrote:
> From: Tom Rix <trix@redhat.com>
>
> clang static analysis reports this problem
>
> mos7720.c:352:2: warning: Undefined or garbage value returned to caller
> return d;
> ^~~~~~~~
>
> In the parport_mos7715_read_data()'s call to read_mos_reg(), 'd' is
> only set after the alloc block.
>
> buf = kmalloc(1, GFP_KERNEL);
> if (!buf)
> return -ENOMEM;
>
> Although the problem is reported in parport_most7715_read_data(),
> none of the callee's of read_mos_reg() check the return status.
>
> So move the clearing of data to before the malloc.
>
> Fixes: 0d130367abf5 ("USB: serial: mos7720: fix control-message error handling")
> Signed-off-by: Tom Rix <trix@redhat.com>
> ---
> drivers/usb/serial/mos7720.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/usb/serial/mos7720.c b/drivers/usb/serial/mos7720.c
> index 41ee2984a0df..23e8162c768b 100644
> --- a/drivers/usb/serial/mos7720.c
> +++ b/drivers/usb/serial/mos7720.c
> @@ -214,6 +214,7 @@ static int read_mos_reg(struct usb_serial *serial, unsigned int serial_portnum,
> u8 *buf;
> int status;
>
> + *data = 0;
> buf = kmalloc(1, GFP_KERNEL);
> if (!buf)
> return -ENOMEM;
I added a clearing of the buffer to this error path instead to avoid the
redundant assignment for every call due to something which will
basically never happen.
> @@ -227,7 +228,6 @@ static int read_mos_reg(struct usb_serial *serial, unsigned int serial_portnum,
> "mos7720: usb_control_msg() failed: %d\n", status);
> if (status >= 0)
> status = -EIO;
> - *data = 0;
> }
>
> kfree(buf);
Johan
^ permalink raw reply [flat|nested] 3+ messages in thread
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2021-01-11 22:09 [PATCH] USB: serial: mos7720: improve handling of a kmalloc failure in read_mos_reg() trix
2021-01-11 22:31 ` Nathan Chancellor
2021-01-12 8:57 ` Johan Hovold
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