2019-05-28 14:31:24

by Geert Uytterhoeven

Subject: [PATCH 5/5] [RFC] devlink: Fix uninitialized error code in devlink_fmsg_prepare_skb()

With gcc 4.1:

net/core/devlink.c: In function ‘devlink_fmsg_prepare_skb’:
net/core/devlink.c:4325: warning: ‘err’ may be used uninitialized in this function

Indeed, if the list has less than *start entries, an uninitialized error
code will be returned.

Fix this by preinitializing err to zero.

Fixes: 1db64e8733f65381 ("devlink: Add devlink formatted message (fmsg) API")
Signed-off-by: Geert Uytterhoeven <[email protected]>
---
I don't know if this can really happen, and if this is the right fix.
Perhaps err should be initialized to some valid error code instead?
---
net/core/devlink.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/core/devlink.c b/net/core/devlink.c
index d43bc52b8840d76b..91377e4eae9a43c1 100644
--- a/net/core/devlink.c
+++ b/net/core/devlink.c
@@ -4321,8 +4321,8 @@ devlink_fmsg_prepare_skb(struct devlink_fmsg *fmsg, struct sk_buff *skb,
{
struct devlink_fmsg_item *item;
struct nlattr *fmsg_nlattr;
+ int err = 0;
int i = 0;
- int err;

fmsg_nlattr = nla_nest_start_noflag(skb, DEVLINK_ATTR_FMSG);
if (!fmsg_nlattr)
--
2.17.1

2019-05-28 14:41:38

by Eran Ben Elisha

Subject: Re: [PATCH 5/5] [RFC] devlink: Fix uninitialized error code in devlink_fmsg_prepare_skb()

On 5/28/2019 5:24 PM, Geert Uytterhoeven wrote:
> With gcc 4.1:
>
> net/core/devlink.c: In function ‘devlink_fmsg_prepare_skb’:
> net/core/devlink.c:4325: warning: ‘err’ may be used uninitialized in this function
>
> Indeed, if the list has less than *start entries, an uninitialized error
> code will be returned.

The logic guarantees that start is smaller than the length of the list.
but I guess that the compiler can't detect that.

Reviewed-by: Eran Ben Elisha <[email protected]>

>
> Fix this by preinitializing err to zero.
>
> Fixes: 1db64e8733f65381 ("devlink: Add devlink formatted message (fmsg) API")
> Signed-off-by: Geert Uytterhoeven <[email protected]>
> ---
> I don't know if this can really happen, and if this is the right fix.
> Perhaps err should be initialized to some valid error code instead?
> ---
> net/core/devlink.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/net/core/devlink.c b/net/core/devlink.c
> index d43bc52b8840d76b..91377e4eae9a43c1 100644
> --- a/net/core/devlink.c
> +++ b/net/core/devlink.c
> @@ -4321,8 +4321,8 @@ devlink_fmsg_prepare_skb(struct devlink_fmsg *fmsg, struct sk_buff *skb,
> {
> struct devlink_fmsg_item *item;
> struct nlattr *fmsg_nlattr;
> + int err = 0;
> int i = 0;
> - int err;
>
> fmsg_nlattr = nla_nest_start_noflag(skb, DEVLINK_ATTR_FMSG);
> if (!fmsg_nlattr)
>

2019-05-29 08:06:30

by Jiri Pirko

Subject: Re: [PATCH 5/5] [RFC] devlink: Fix uninitialized error code in devlink_fmsg_prepare_skb()

Tue, May 28, 2019 at 04:24:24PM CEST, [email protected] wrote:
>With gcc 4.1:
>
> net/core/devlink.c: In function ‘devlink_fmsg_prepare_skb’:
> net/core/devlink.c:4325: warning: ‘err’ may be used uninitialized in this function
>
>Indeed, if the list has less than *start entries, an uninitialized error
>code will be returned.
>
>Fix this by preinitializing err to zero.
>
>Fixes: 1db64e8733f65381 ("devlink: Add devlink formatted message (fmsg) API")
>Signed-off-by: Geert Uytterhoeven <[email protected]>
>---
>I don't know if this can really happen, and if this is the right fix.
>Perhaps err should be initialized to some valid error code instead?

0 is correct here.
Acked-by: Jiri Pirko <[email protected]>

Thanks!

>---
> net/core/devlink.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
>diff --git a/net/core/devlink.c b/net/core/devlink.c
>index d43bc52b8840d76b..91377e4eae9a43c1 100644
>--- a/net/core/devlink.c
>+++ b/net/core/devlink.c
>@@ -4321,8 +4321,8 @@ devlink_fmsg_prepare_skb(struct devlink_fmsg *fmsg, struct sk_buff *skb,
> {
> struct devlink_fmsg_item *item;
> struct nlattr *fmsg_nlattr;
>+ int err = 0;
> int i = 0;
>- int err;
>
> fmsg_nlattr = nla_nest_start_noflag(skb, DEVLINK_ATTR_FMSG);
> if (!fmsg_nlattr)
>--
>2.17.1
>