linux-kernel - Re: [PATCH 1/5] lightnvm: Fix uninitialized pointer in nvm_remove

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Message-ID: <4b666e32-04b6-228a-691d-0745fa48a57f@lightnvm.io>
Date:   Wed, 29 May 2019 10:08:24 +0200
From:   Matias Bjørling <mb@...htnvm.io>
To:     Geert Uytterhoeven <geert@...ux-m68k.org>,
        Igor Konopko <igor.j.konopko@...el.com>,
        David Howells <dhowells@...hat.com>,
        "Mohit P . Tahiliani" <tahiliani@...k.edu.in>,
        Takashi Sakamoto <o-takashi@...amocchi.jp>,
        Eran Ben Elisha <eranbe@...lanox.com>,
        Jiri Pirko <jiri@...lanox.com>,
        "David S . Miller" <davem@...emloft.net>,
        Jamal Hadi Salim <jhs@...atatu.com>,
        Cong Wang <xiyou.wangcong@...il.com>,
        Clemens Ladisch <clemens@...isch.de>,
        Jaroslav Kysela <perex@...ex.cz>,
        Takashi Iwai <tiwai@...e.com>, Joe Perches <joe@...ches.com>,
        Arnd Bergmann <arnd@...db.de>,
        Dan Carpenter <dan.carpenter@...cle.com>
Cc:     linux-block@...r.kernel.org, netdev@...r.kernel.org,
        linux-afs@...ts.infradead.org, alsa-devel@...a-project.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/5] lightnvm: Fix uninitialized pointer in
 nvm_remove_tgt()

On 5/28/19 4:24 PM, Geert Uytterhoeven wrote:
> With gcc 4.1:
> 
>      drivers/lightnvm/core.c: In function ‘nvm_remove_tgt’:
>      drivers/lightnvm/core.c:510: warning: ‘t’ is used uninitialized in this function
> 
> Indeed, if no NVM devices have been registered, t will be an
> uninitialized pointer, and may be dereferenced later.  A call to
> nvm_remove_tgt() can be triggered from userspace by issuing the
> NVM_DEV_REMOVE ioctl on the lightnvm control device.
> 
> Fix this by preinitializing t to NULL.
> 
> Fixes: 843f2edbdde085b4 ("lightnvm: do not remove instance under global lock")
> Signed-off-by: Geert Uytterhoeven <geert@...ux-m68k.org>
> ---
>   drivers/lightnvm/core.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/lightnvm/core.c b/drivers/lightnvm/core.c
> index 0df7454832efe082..aa017f48eb8c588c 100644
> --- a/drivers/lightnvm/core.c
> +++ b/drivers/lightnvm/core.c
> @@ -492,7 +492,7 @@ static void __nvm_remove_target(struct nvm_target *t, bool graceful)
>    */
>   static int nvm_remove_tgt(struct nvm_ioctl_remove *remove)
>   {
> -	struct nvm_target *t;
> +	struct nvm_target *t = NULL;
>   	struct nvm_dev *dev;
>   
>   	down_read(&nvm_lock);
> 

Thanks Geert. Would you like me to carry the patch?