2020-05-14 08:06:53

by Macpaul Lin

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Subject: [PATCH] usb: gadget: u_serial: fix coverity warning: negative index at array

This issue has been reported by coverity scanner.
Replace "int portnum" by "unsigned int", this void negative index at
array.

Signed-off-by: Stan Lu <[email protected]>
Signed-off-by: Macpaul Lin <[email protected]>
---
drivers/usb/gadget/function/u_serial.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/usb/gadget/function/u_serial.c b/drivers/usb/gadget/function/u_serial.c
index 8167d37..53951f2 100644
--- a/drivers/usb/gadget/function/u_serial.c
+++ b/drivers/usb/gadget/function/u_serial.c
@@ -587,7 +587,7 @@ static int gs_start_io(struct gs_port *port)
*/
static int gs_open(struct tty_struct *tty, struct file *file)
{
- int port_num = tty->index;
+ unsigned int port_num = tty->index;
struct gs_port *port;
int status = 0;

@@ -1211,7 +1211,7 @@ int gserial_alloc_line_no_console(unsigned char *line_num)
struct gs_port *port;
struct device *tty_dev;
int ret;
- int port_num;
+ unsigned int port_num;

coding.dwDTERate = cpu_to_le32(9600);
coding.bCharFormat = 8;
--
1.7.9.5


2020-05-14 09:43:03

by Felipe Balbi

[permalink] [raw]
Subject: Re: [PATCH] usb: gadget: u_serial: fix coverity warning: negative index at array

Macpaul Lin <[email protected]> writes:

> This issue has been reported by coverity scanner.
> Replace "int portnum" by "unsigned int", this void negative index at
> array.
>
> Signed-off-by: Stan Lu <[email protected]>
> Signed-off-by: Macpaul Lin <[email protected]>

please rebase on testing/fixes

error: patch failed: drivers/usb/gadget/function/u_serial.c:587
error: drivers/usb/gadget/function/u_serial.c: patch does not apply
hint: Use 'git am --show-current-patch=diff' to see the failed patch
Applying: usb: gadget: u_serial: fix coverity warning: negative index at array
Patch failed at 0001 usb: gadget: u_serial: fix coverity warning: negative index at array
When you have resolved this problem, run "git am --continue".
If you prefer to skip this patch, run "git am --skip" instead.
To restore the original branch and stop patching, run "git am --abort".

--
balbi


Attachments:
signature.asc (847.00 B)

2020-05-14 14:24:34

by Alan Stern

[permalink] [raw]
Subject: Re: [PATCH] usb: gadget: u_serial: fix coverity warning: negative index at array

On Thu, May 14, 2020 at 04:05:00PM +0800, Macpaul Lin wrote:
> This issue has been reported by coverity scanner.
> Replace "int portnum" by "unsigned int", this void negative index at
> array.

Can you please explain this more fully? Why does coverity think the
code might use a negative array index? Is there some possibility that
the portnum value might actually be negative?

It's noticeable that your patch doesn't actually change any values, only
the type. This means that if the code was buggy before, it's still
buggy. Alternatively, if the code wasn't buggy before then coverity got
a false positive, so no change should be needed.

Alan Stern

> Signed-off-by: Stan Lu <[email protected]>
> Signed-off-by: Macpaul Lin <[email protected]>
> ---
> drivers/usb/gadget/function/u_serial.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/usb/gadget/function/u_serial.c b/drivers/usb/gadget/function/u_serial.c
> index 8167d37..53951f2 100644
> --- a/drivers/usb/gadget/function/u_serial.c
> +++ b/drivers/usb/gadget/function/u_serial.c
> @@ -587,7 +587,7 @@ static int gs_start_io(struct gs_port *port)
> */
> static int gs_open(struct tty_struct *tty, struct file *file)
> {
> - int port_num = tty->index;
> + unsigned int port_num = tty->index;
> struct gs_port *port;
> int status = 0;
>
> @@ -1211,7 +1211,7 @@ int gserial_alloc_line_no_console(unsigned char *line_num)
> struct gs_port *port;
> struct device *tty_dev;
> int ret;
> - int port_num;
> + unsigned int port_num;
>
> coding.dwDTERate = cpu_to_le32(9600);
> coding.bCharFormat = 8;
> --
> 1.7.9.5