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Re: [xfs-masters] Re: [PATCH][XFS][resend] fix memory leak in xfs_inactive()

To: Linux Kernel Mailing List <linux-kernel@...>
Cc: David Chinner <dgc@...>, <xfs-masters@...>, <xfs@...>, Andrew Morton <akpm@...>, Jesper Juhl <jesper.juhl@...>
Date: Saturday, June 30, 2007 - 7:16 pm

(this is back from May 16 2007, resending since it doesn't look like
the patch ever made it in anywhere)

The Coverity checker found a memory leak in xfs_inactive().

The offending code is this bit :

1671 tp = xfs_trans_alloc(mp, XFS_TRANS_INACTIVE);

At conditional (1): "truncate != 0" taking true path

1672 if (truncate) {
1673 /*
1674 * Do the xfs_itruncate_start() call before
1675 * reserving any log space because itruncate_start
1676 * will call into the buffer cache and we can't
1677 * do that within a transaction.
1678 */
1679 xfs_ilock(ip, XFS_IOLOCK_EXCL);
1680
1681 error = xfs_itruncate_start(ip, XFS_ITRUNC_DEFINITE, 0);

At conditional (2): "error != 0" taking true path

1682 if (error) {
1683 xfs_iunlock(ip, XFS_IOLOCK_EXCL);

Event leaked_storage: Returned without freeing storage "tp"
Also see events: [alloc_fn][var_assign]

1684 return VN_INACTIVE_CACHE;
1685 }

So, the code allocates a transaction, but in the case where 'truncate' is !=0 and xfs_itruncate_start(ip, XFS_ITRUNC_DEFINITE, 0); happens to return an error, we'll just return from the function without dealing with the memory allocated byxfs_trans_alloc() and assigned to 'tp', thus it'll be orphaned/leaked - not good.

The bug was introduced by this commit:
http://git2.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=comm...

The patch below is

From: Dave Chinner <dgc@sgi.com>
Signed-off-by: Jesper Juhl <jesper.juhl@gmail.com>
---
fs/xfs/xfs_vnodeops.c | 1 +
1 file changed, 1 insertion(+)

Index: 2.6.x-xfs-new/fs/xfs/xfs_vnodeops.c
===================================================================
--- 2.6.x-xfs-new.orig/fs/xfs/xfs_vnodeops.c 2007-05-11 16:0...

To: Jesper Juhl <jesper.juhl@...>
Cc: Linux Kernel Mailing List <linux-kernel@...>, David Chinner <dgc@...>, <xfs-masters@...>, <xfs@...>, Andrew Morton <akpm@...>
Date: Sunday, July 1, 2007 - 6:31 pm

http://oss.sgi.com/cgi-bin/cvsweb.cgi/linux-2.6-xfs/fs/xfs/xfs_vnodeops....

Will get merged in 2.6.23-rc1 window.

Cheers,

Dave.
--
Dave Chinner
Principal Engineer
SGI Australian Software Group
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To: <xfs-masters@...>
Cc: Jesper Juhl <jesper.juhl@...>, Linux Kernel Mailing List <linux-kernel@...>, David Chinner <dgc@...>, <xfs@...>, Andrew Morton <akpm@...>
Date: Sunday, July 1, 2007 - 9:23 pm

Also, in our master branch of oss git tree (used by Andrew)..
git pull git://oss.sgi.com:8090/xfs/xfs-2.6.git master

commit 1ccb0a872f9cb5056b534fc80c746a68154e08c0
Author: Jesper Juhl <jesper.juhl@gmail.com>
Date: Thu Jun 28 16:43:14 2007 +1000

[XFS] Cancel transactions on xfs_itruncate_start error.

SGI-PV: 966502
SGI-Modid: xfs-linux-melb:xfs-kern:28943a

Signed-off-by: Jesper Juhl <jesper.juhl@gmail.com>
Signed-off-by: David Chinner <dgc@sgi.com>
Signed-off-by: Tim Shimmin <tes@sgi.com>

--Tim

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To: David Chinner <dgc@...>
Cc: Linux Kernel Mailing List <linux-kernel@...>, <xfs-masters@...>, <xfs@...>, Andrew Morton <akpm@...>
Date: Sunday, July 1, 2007 - 9:06 pm

Ok, good to know, I thought it had been forgotten :-)

--
Jesper Juhl <jesper.juhl@gmail.com>
Don't top-post http://www.catb.org/~esr/jargon/html/T/top-post.html
Plain text mails only, please http://www.expita.com/nomime.html
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