linux-kernel - Re: [PATCH] staging: lustre: llite: Fix variable length array warning

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Date:   Sat, 6 May 2017 13:16:29 -0700
From:   Guru Das Srinagesh <gurooodas@...il.com>
To:     Joe Perches <joe@...ches.com>
Cc:     oleg.drokin@...el.com, andreas.dilger@...el.com,
        jsimmons@...radead.org, gregkh@...uxfoundation.org,
        john.hammond@...el.com, lustre-devel@...ts.lustre.org,
        devel@...verdev.osuosl.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] staging: lustre: llite: Fix variable length array warning

On Fri, May 05, 2017 at 01:52:36AM -0700, Joe Perches wrote:
> On Thu, 2017-05-04 at 23:41 -0700, Guru Das Srinagesh wrote:
> > Fix sparse warning "warning: Variable length array is used." by using
> > kmalloc_array to allocate the required amount of memory instead and
> > kfree to deallocate memory after use.
> []
> > diff --git a/drivers/staging/lustre/lustre/llite/xattr.c b/drivers/staging/lustre/lustre/llite/xattr.c
> []
> > @@ -86,7 +86,8 @@ ll_xattr_set_common(const struct xattr_handler *handler,
> >  		    const char *name, const void *value, size_t size,
> >  		    int flags)
> >  {
> > -	char fullname[strlen(handler->prefix) + strlen(name) + 1];
> > +	int fullname_len = strlen(handler->prefix) + strlen(name) + 1;
> > +	char *fullname = kmalloc_array(fullname_len, sizeof(char), GFP_KERNEL);
> 
> What happens when this allocation fails?
> 
Thanks for rightly pointing out the omission of kmalloc_array failure case
handling code. I could check for fullname being NULL and then return -ENOMEM
right there in both functions. I'll go ahead and send a v2 of this patch, with
this modification incorporated, unless there are any more comments or concerns.
Could you please let me know? Thank you.