Re: [PATCH] kexec: avoid freeing NULL pointer in function kimage_crash_alloc

Simon Horman
2013-02-23T10:00:56Z

On Fri, Feb 22, 2013 at 12:50:50PM +0800, Zhang Yanfei wrote:
> Though there is no error if we free a NULL pointer, I think we could
> avoid this behaviour. Change the code a little in kimage_crash_alloc()
> could avoid this kind of unnecessary free.
>
> Cc: "Eric W. Biederman" <ebiederm@xmission.com>
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Signed-off-by: Zhang Yanfei <zhangyanfei@cn.fujitsu.com>

Reviewed-by: Simon Horman <horms@verge.net.au>

> ---
> kernel/kexec.c | 15 +++++++--------
> 1 files changed, 7 insertions(+), 8 deletions(-)
>
> diff --git a/kernel/kexec.c b/kernel/kexec.c
> index 5e4bd78..4e96fa7 100644
> --- a/kernel/kexec.c
> +++ b/kernel/kexec.c
> @@ -310,7 +310,7 @@ static int kimage_crash_alloc(struct kimage **rimage, unsigned long entry,
> mend = mstart + image->segment[i].memsz - 1;
> /* Ensure we are within the crash kernel limits */
> if ((mstart < crashk_res.start) || (mend > crashk_res.end))
> - goto out;
> + goto out_free;
> }
>
> /*
> @@ -323,16 +323,15 @@ static int kimage_crash_alloc(struct kimage **rimage, unsigned long entry,
> get_order(KEXEC_CONTROL_PAGE_SIZE));
> if (!image->control_code_page) {
> printk(KERN_ERR "Could not allocate control_code_buffer\n");
> - goto out;
> + goto out_free;
> }
>
> - result = 0;
> -out:
> - if (result == 0)
> - *rimage = image;
> - else
> - kfree(image);
> + *rimage = image;
> + return 0;
>
> +out_free:
> + kfree(image);
> +out:
> return result;
> }
>
> --
> 1.7.1
>
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> http://lists.infradead.org/mailman/listinfo/kexec
>

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