ext4: fix memory leak in xattr code.

ext4: fix memory leak in xattr code.

[Dave Jones]

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 <davej@fedoraproject.org>

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;

Re: ext4: fix memory leak in xattr code.

[Eric Sandeen]

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 <davej@fedoraproject.org>

Looks right to me.

Reviewed-by: Eric Sandeen <sandeen@redhat.com>

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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Re: ext4: fix memory leak in xattr code.

[Theodore Ts'o]

Thanks, applied with a minor bug fix...

						- Ted

commit 8484764f97a840df851f4586079f28715f13318e
Author: Dave Jones <davej@redhat.com>
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 <davej@fedoraproject.org>
    Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
    Reviewed-by: Eric Sandeen <sandeen@redhat.com>

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;