Re: [PATCH] iio: multiplexer: add NULL check on devm_kzalloc() return value

From: Gustavo A. R. Silva
Date: Fri Jul 07 2017 - 00:52:13 EST

Quoting Peter Rosin <peda@xxxxxxxxxx>:

On 2017-07-07 06:35, Gustavo A. R. Silva wrote:
Hi Peter,

Quoting Peter Rosin <peda@xxxxxxxxxx>:

On 2017-07-07 00:08, Gustavo A. R. Silva wrote:
Check return value from call to devm_kzalloc()
in order to prevent a NULL pointer dereference.

Right, thanks for finding that one! There's another one inside the
for loop that is just starting in the context of this patch. Care
to fix checking the return value of that devm_kmemdup as well?

Sure, I'll send a new patch shortly.

And someone should perhaps teach Coccinelle about devm_kmemdup...

Good catch, I just implemented that script.

This issue was detected using Coccinelle and the following semantic patch:

expression x;
identifier fld;

* x = devm_kzalloc(...);
... when != x == NULL

One of these blank lines should perhaps be a "Fixes:" tag?

mmm, I don't get this...

If you add a Fixes-tag, like below, you help the stable kernel maintainers
decide what to look at. In this case it might be overkill since the thing
you fix is so fresh and does not apply to any old kernel. But I think it
is a good habit...

Fixes: 7ba9df54b091 ("iio: multiplexer: new iio category and iio-mux driver")

(and it is a bit unusual to see two blank lines before the SoB-tag)

Sorry for not spelling it out the first time.

Oh, I get it now. Thank you very much for clarifying. I will definitely keep that in mind for future fixes when that could apply.

Gustavo A. R. Silva