Re: [ 05/11] ext4: fix memory leak in xattr

From: Dave Jones
Date: Mon Oct 21 2013 - 12:37:56 EST


On Fri, Oct 18, 2013 at 12:53:34PM -0700, Greg Kroah-Hartman wrote:
> 3.4-stable review patch. If anyone has any objections, please let me know.
>
> ------------------
>
> From: Dave Jones <davej@xxxxxxxxxx>
>
> commit 6e4ea8e33b2057b85d75175dd89b93f5e26de3bc upstream.
>
> If we take the 2nd retry path in ext4_expand_extra_isize_ea, we
> potentionally return from the function without having freed these
> allocations. If we don't do the return, we over-write the previous
> allocation pointers, so we leak either way.
>
> Spotted with Coverity.
>
> [ Fixed by tytso to set is and bs to NULL after freeing these
> pointers, in case in the retry loop we later end up triggering an
> error causing a jump to cleanup, at which point we could have a double
> free bug. -- Ted ]
>
> Signed-off-by: Dave Jones <davej@xxxxxxxxxxxxxxxxx>
> Signed-off-by: "Theodore Ts'o" <tytso@xxxxxxx>
> Reviewed-by: Eric Sandeen <sandeen@xxxxxxxxxx>
> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

I'm still waiting to hear if we also need this..

Ted ?

--

If we take the retry path here, we end up potentially overwriting bh, leaving
it with an elevated reference count.

Signed-off-by: Dave Jones <davej@xxxxxxxxxxxxxxxxx>

diff --git a/fs/ext4/xattr.c b/fs/ext4/xattr.c
index 03e9beb..1423c48 100644
--- a/fs/ext4/xattr.c
+++ b/fs/ext4/xattr.c
@@ -1352,6 +1352,7 @@ retry:
new_extra_isize = s_min_extra_isize;
kfree(is); is = NULL;
kfree(bs); bs = NULL;
+ brelse(bh);
goto retry;
}
error = -1;

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