linux-kernel - Re: [Patch] fs/binfmt

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Date:	Sat, 3 May 2008 16:26:11 +0300 (EEST)
From:	Pekka J Enberg <penberg@...helsinki.fi>
To:	WANG Cong <xiyou.wangcong@...il.com>
cc:	LKML <linux-kernel@...r.kernel.org>,
	Eric Youngdale <ericy@...s.com>, viro@...iv.linux.org.uk,
	linux-fsdevel@...r.kernel.org, Andrew Morton <akpm@...l.org>
Subject: Re: [Patch] fs/binfmt_elf.c: fix a wrong free

On Sat, 3 May 2008, WANG Cong wrote:
> Fix a wrong free in fs/binfmt_elf.c::elf_core_dump().
> 
> Signed-off-by: WANG Cong <wangcong@...ux.org>
> Cc: Alexander Viro <viro@...iv.linux.org.uk>
> Cc: Eric Youngdale <ericy@...s.com>
> 
> ---
>  fs/binfmt_elf.c |    2 +-
>  1 files changed, 1 insertions(+), 1 deletions(-)
> 
> diff --git a/fs/binfmt_elf.c b/fs/binfmt_elf.c
> index b25707f..43254e3 100644
> --- a/fs/binfmt_elf.c
> +++ b/fs/binfmt_elf.c
> @@ -2032,10 +2032,10 @@ static int elf_core_dump(long signr, struct pt_regs *regs, struct file *file, un
>  
>  end_coredump:
>  	set_fs(fs);
> +	free_note_info(&info);
>  
>  cleanup:
>  	kfree(elf);
> -	free_note_info(&info);
>  	return has_dumped;
>  }

Looks like fill_note_info() requires that you call free_note_info() if it 
fails; otherwise we'll leak memory. So perhaps something like the 
following totally untested patch?

		Pekka

diff --git a/fs/binfmt_elf.c b/fs/binfmt_elf.c
index b25707f..febd208 100644
--- a/fs/binfmt_elf.c
+++ b/fs/binfmt_elf.c
@@ -1917,7 +1917,7 @@ static int elf_core_dump(long signr, struct pt_regs *regs, struct file *file, un
 	 */
 	if (!fill_note_info(elf, segs + 1, /* including notes section */
 			    &info, signr, regs))
-		goto cleanup;
+		goto cleanup_note;
 
 	has_dumped = 1;
 	current->flags |= PF_DUMPCORE;
@@ -2033,9 +2033,11 @@ static int elf_core_dump(long signr, struct pt_regs *regs, struct file *file, un
 end_coredump:
 	set_fs(fs);
 
+cleanup_note:
+	free_note_info(&info);
+
 cleanup:
 	kfree(elf);
-	free_note_info(&info);
 	return has_dumped;
 }
 
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