linux-kernel - Re: [PATCH] userns: suppress kmemleak message

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Message-ID: <20161103140427.5620dde3@jkicinski-Precision-T1700>
Date:   Thu, 3 Nov 2016 14:04:27 +0000
From:   Jakub Kicinski <jakub.kicinski@...ronome.com>
To:     Dmitry Torokhov <dmitry.torokhov@...il.com>
Cc:     "Eric W. Biederman" <ebiederm@...ssion.com>,
        linux-kernel@...r.kernel.org, Kees Cook <keescook@...omium.org>,
        Johannes Berg <johannes@...solutions.net>,
        Maciej Żenczykowski <zenczykowski@...il.com>
Subject: Re: [PATCH] userns: suppress kmemleak message

On Wed, 2 Nov 2016 22:39:48 -0700, Dmitry Torokhov wrote:
> We do not ever intend to unregister "user" sysctl table, unfortunately
> it leads kmemleak to believe that we are leaking memory:
> 
> unreferenced object 0xffff8807383bfd48 (size 96):
>   comm "swapper/0", pid 1, jiffies 4294894636 (age 278.320s)
>   hex dump (first 32 bytes):
>     a0 b4 b0 ba ff ff ff ff 00 00 00 00 01 00 00 00  ................
>     01 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
>   backtrace:
>     [<ffffffffb7de59e8>] kmemleak_alloc+0x28/0x50
>     [<ffffffffb676e2f6>] __kmalloc+0x206/0x5a0
>     [<ffffffffb69be2d3>] __register_sysctl_table+0xb3/0x1130
>     [<ffffffffb69bf36b>] register_sysctl+0x1b/0x20
>     [<ffffffffba840de1>] user_namespace_sysctl_init+0x17/0x4c
>     [<ffffffffb60022b7>] do_one_initcall+0xb7/0x2a0
>     [<ffffffffba7eb102>] kernel_init_freeable+0x597/0x636
>     [<ffffffffb7de0433>] kernel_init+0x13/0x140
>     [<ffffffffb7dfb36a>] ret_from_fork+0x2a/0x40t show
>     [<ffffffffffffffff>] 0xffffffffffffffff
> 
> Let's annotate the pointer as kmemleak_not_leak() to suppress the
> kmemleak false positive.
> 
> Reported-by: Jakub Kicinski <kubakici@...pl>
> Signed-off-by: Dmitry Torokhov <dmitry.torokhov@...il.com>
> ---
> 
> This was only compiled; Jakub, could you give it a spin?

Tested-by: Jakub Kicinski <jakub.kicinski@...ronome.com>

Thanks!