2013-09-20 14:29:31

by Dave Jones

Subject: ext4: fix memory leak in xattr code.

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.

Signed-off-by: Dave Jones <[email protected]>

diff --git a/fs/ext4/xattr.c b/fs/ext4/xattr.c
index c081e34..f3a6220 100644
--- a/fs/ext4/xattr.c
+++ b/fs/ext4/xattr.c
@@ -1350,6 +1350,8 @@ retry:
s_min_extra_isize) {
tried_min_extra_isize++;
new_extra_isize = s_min_extra_isize;
+ kfree(is);
+ kfree(bs);
goto retry;
}
error = -1;

2013-09-20 16:09:01

by Eric Sandeen

Subject: Re: ext4: fix memory leak in xattr code.

On 9/20/13 9:29 AM, Dave Jones wrote:
> 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.
>
> Signed-off-by: Dave Jones <[email protected]>

Looks right to me.

Reviewed-by: Eric Sandeen <[email protected]>

Thanks!

-Eric

> diff --git a/fs/ext4/xattr.c b/fs/ext4/xattr.c
> index c081e34..f3a6220 100644
> --- a/fs/ext4/xattr.c
> +++ b/fs/ext4/xattr.c
> @@ -1350,6 +1350,8 @@ retry:
> s_min_extra_isize) {
> tried_min_extra_isize++;
> new_extra_isize = s_min_extra_isize;
> + kfree(is);
> + kfree(bs);
> goto retry;
> }
> error = -1;
> --
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>

2013-09-22 19:33:41

by Theodore Ts'o

Subject: Re: ext4: fix memory leak in xattr code.

Thanks, applied with a minor bug fix...

- Ted

commit 8484764f97a840df851f4586079f28715f13318e
Author: Dave Jones <[email protected]>
Date: Sun Sep 22 15:31:00 2013 -0400

ext4: fix memory leak in xattr

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 <[email protected]>
Signed-off-by: "Theodore Ts'o" <[email protected]>
Reviewed-by: Eric Sandeen <[email protected]>

diff --git a/fs/ext4/xattr.c b/fs/ext4/xattr.c
index c081e34..3c53192 100644
--- a/fs/ext4/xattr.c
+++ b/fs/ext4/xattr.c
@@ -1350,6 +1350,9 @@ retry:
s_min_extra_isize) {
tried_min_extra_isize++;
new_extra_isize = s_min_extra_isize;
+ kfree(is);
+ kfree(bs);
+ is = bs = NULL;
goto retry;
}
error = -1;