Re: [PATCH v2] livepatch: Reorder to use before freeing a pointer

From: Petr Mladek
Date: Wed Mar 23 2022 - 11:53:17 EST


On Sat 2022-03-19 18:51:43, trix@xxxxxxxxxx wrote:
> From: Tom Rix <trix@xxxxxxxxxx>
>
> Clang static analysis reports this issue
> livepatch-shadow-fix1.c:113:2: warning: Use of
> memory after it is freed
> pr_info("%s: dummy @ %p, prevented leak @ %p\n",
> ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>
> The pointer is freed in the previous statement.
> Reorder the pr_info to report before the free.
>
> Similar issue in livepatch-shadow-fix2.c

I have added the following paragraph:

<snip>
Note that it is a false positive. pr_info() just prints the address.
The freed memory is not accessed. Well, the static analyzer could not
know this easily.
</snip>

> Signed-off-by: Tom Rix <trix@xxxxxxxxxx>

and pushed the patch into livepatching/livepatching.git,
branch for-5.18/selftests-fixes.

IMHO, the patch is so trivial and can be added even in this merge
window. There is no need to create more dances around it ;-)

Let me know if you disagree. I am going to send the pull request
on Friday or Monday.

Best Regards,
Petr