Patchwork ext3: Fix a possible corruption in dx_probe.

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Submitter Tao Ma
Date Aug. 31, 2011, 3:57 p.m.
Message ID <1314806244-8434-1-git-send-email-tm@tao.ma>
Download mbox | patch
Permalink /patch/112602/
State Not Applicable
Headers show

Comments

Tao Ma - Aug. 31, 2011, 3:57 p.m.
From: Tao Ma <boyu.mt@taobao.com>

For all the callers of dx_probe, frame_in is passed in uninitialized.
So we should set frame->bh to NULL in the beginning of while, not
the end. Otherwise, the first "goto fail2" will try to brelse(frame->bh)
while frame->bh is still invalid.

Cc: Jan Kara <jack@suse.cz>
Signed-off-by: Tao Ma <boyu.mt@taobao.com>
---
 fs/ext3/namei.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
Jan Kara - Sept. 1, 2011, 4:43 p.m.
On Wed 31-08-11 23:57:24, Tao Ma wrote:
> From: Tao Ma <boyu.mt@taobao.com>
> 
> For all the callers of dx_probe, frame_in is passed in uninitialized.
> So we should set frame->bh to NULL in the beginning of while, not
> the end. Otherwise, the first "goto fail2" will try to brelse(frame->bh)
> while frame->bh is still invalid.
  I think this happens at the beginning of dx_probe().

								Honza
> 
> Cc: Jan Kara <jack@suse.cz>
> Signed-off-by: Tao Ma <boyu.mt@taobao.com>
> ---
>  fs/ext3/namei.c |    2 +-
>  1 files changed, 1 insertions(+), 1 deletions(-)
> 
> diff --git a/fs/ext3/namei.c b/fs/ext3/namei.c
> index 34b6d9b..45468b9 100644
> --- a/fs/ext3/namei.c
> +++ b/fs/ext3/namei.c
> @@ -404,6 +404,7 @@ dx_probe(struct qstr *entry, struct inode *dir,
>  	dxtrace (printk("Look up %x", hash));
>  	while (1)
>  	{
> +		frame->bh = NULL;
>  		count = dx_get_count(entries);
>  		if (!count || count > dx_get_limit(entries)) {
>  			ext3_warning(dir->i_sb, __func__,
> @@ -458,7 +459,6 @@ dx_probe(struct qstr *entry, struct inode *dir,
>  			goto fail2;
>  		}
>  		frame++;
> -		frame->bh = NULL;
>  	}
>  fail2:
>  	while (frame >= frame_in) {
> -- 
> 1.7.0.4
>

Patch

diff --git a/fs/ext3/namei.c b/fs/ext3/namei.c
index 34b6d9b..45468b9 100644
--- a/fs/ext3/namei.c
+++ b/fs/ext3/namei.c
@@ -404,6 +404,7 @@  dx_probe(struct qstr *entry, struct inode *dir,
 	dxtrace (printk("Look up %x", hash));
 	while (1)
 	{
+		frame->bh = NULL;
 		count = dx_get_count(entries);
 		if (!count || count > dx_get_limit(entries)) {
 			ext3_warning(dir->i_sb, __func__,
@@ -458,7 +459,6 @@  dx_probe(struct qstr *entry, struct inode *dir,
 			goto fail2;
 		}
 		frame++;
-		frame->bh = NULL;
 	}
 fail2:
 	while (frame >= frame_in) {