linux-kernel - Re: [PATCH] pid: fix uninitialized retval in alloc

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Message-ID: <e9eed2e9-5bcf-1978-3776-b8b25f92ac5b@nvidia.com>
Date:   Tue, 10 Mar 2020 20:33:31 -0700
From:   John Hubbard <jhubbard@...dia.com>
To:     Christian Brauner <christian.brauner@...ntu.com>
CC:     Stephen Rothwell <sfr@...b.auug.org.au>,
        Linux Next <linux-next@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] pid: fix uninitialized retval in alloc_pid()

On 3/10/20 8:30 PM, Christian Brauner wrote:
> On Tue, Mar 10, 2020 at 08:21:53PM -0700, John Hubbard wrote:
>> Commit 8deb24dcb89cb ("pid: make ENOMEM return value more obvious")
>> left the return value uninitialized in one error case. The justification
>> for the above commit included a statement that retval is "initialized on
>> ever[y] failure path in the loop". However, that is not quite good
>> enough because there is an earlier case that is before the loop. And
>> also, it's more maintenance and merge-safe to initialize it once at the
>> top, as evidenced by this build warning that we now have.
>>
>> Therefore, restore the top-level initialization of retval.
>>
>> Also move the descriptive comment up, and remove the now-redundant
>> later initialization of retval.
>>
>> Fixes: 8deb24dcb89cb ("pid: make ENOMEM return value more obvious")
>> Cc: Christian Brauner <christian.brauner@...ntu.com>
>> Signed-off-by: John Hubbard <jhubbard@...dia.com>
> 
> Thanks. I already have a fixed-up version in my tree after Stephen
> reported it earlier today:
> https://git.kernel.org/pub/scm/linux/kernel/git/brauner/linux.git/commit/?h=fixes&id=10dab84caf400f2f5f8b010ebb0c7c4272ec5093
> 
> (Fwiw, we can't just move the it back up. It needs to be set after the
> loop too because it can be set to EPERM before. See


OK, yes. Sounds good.

thanks,
-- 
John Hubbard
NVIDIA

> https://git.kernel.org/pub/scm/linux/kernel/git/brauner/linux.git/commit/?h=fixes&id=b26ebfe12f34f372cf041c6f801fa49c3fb382c5
> for the motiviation for the comment.)
> 
> Christian
>