[PATCH] nilfs2: fix dereferencing freed memory

[PATCH] nilfs2: fix dereferencing freed memory

[Ferry Meng]

Fix smatch warning:

fs/nilfs2/gcinode.c:103 nilfs_gccache_submit_read_data() error:
dereferencing freed memory 'bh'

Signed-off-by: Ferry Meng <mengferry-KPsoFbNs7GizrGE5bRqYAgC/G2K4zDHf@public.gmane.org>

diff --git a/fs/nilfs2/gcinode.c b/fs/nilfs2/gcinode.c
index 48fe71d309cb..6319e825f317 100644
--- a/fs/nilfs2/gcinode.c
+++ b/fs/nilfs2/gcinode.c
@@ -73,10 +73,8 @@ int nilfs_gccache_submit_read_data(struct inode *inode, sector_t blkoff,
 		struct the_nilfs *nilfs = inode->i_sb->s_fs_info;
 
 		err = nilfs_dat_translate(nilfs->ns_dat, vbn, &pbn);
-		if (unlikely(err)) { /* -EIO, -ENOMEM, -ENOENT */
-			brelse(bh);
+		if (unlikely(err)) /* -EIO, -ENOMEM, -ENOENT */
 			goto failed;
-		}
 	}
 
 	lock_buffer(bh);
@@ -102,6 +100,8 @@ int nilfs_gccache_submit_read_data(struct inode *inode, sector_t blkoff,
  failed:
 	unlock_page(bh->b_page);
 	put_page(bh->b_page);
+	if (err)
+		brelse(bh);
 	return err;
 }
 
-- 
2.19.1.6.gb485710b

Re: [PATCH] nilfs2: fix dereferencing freed memory

[Ryusuke Konishi]

On Fri, Aug 18, 2023 at 6:20 PM Ferry Meng wrote:
>
> Fix smatch warning:
>
> fs/nilfs2/gcinode.c:103 nilfs_gccache_submit_read_data() error:
> dereferencing freed memory 'bh'
>
> Signed-off-by: Ferry Meng <mengferry@linux.alibaba.com>
>
> diff --git a/fs/nilfs2/gcinode.c b/fs/nilfs2/gcinode.c
> index 48fe71d309cb..6319e825f317 100644
> --- a/fs/nilfs2/gcinode.c
> +++ b/fs/nilfs2/gcinode.c
> @@ -73,10 +73,8 @@ int nilfs_gccache_submit_read_data(struct inode *inode, sector_t blkoff,
>                 struct the_nilfs *nilfs = inode->i_sb->s_fs_info;
>
>                 err = nilfs_dat_translate(nilfs->ns_dat, vbn, &pbn);
> -               if (unlikely(err)) { /* -EIO, -ENOMEM, -ENOENT */
> -                       brelse(bh);
> +               if (unlikely(err)) /* -EIO, -ENOMEM, -ENOENT */
>                         goto failed;
> -               }
>         }
>
>         lock_buffer(bh);
> @@ -102,6 +100,8 @@ int nilfs_gccache_submit_read_data(struct inode *inode, sector_t blkoff,
>   failed:
>         unlock_page(bh->b_page);
>         put_page(bh->b_page);
> +       if (err)
> +               brelse(bh);
>         return err;
>  }
>
> --
> 2.19.1.6.gb485710b
>

Ah, this is almost identical to the patch Pan Bian sent me earlier.
After a closer look, I'll pick up his patch instead with a
"Reported-by" tag of your name on it.

Anyway, thanks for your feedback.

Regards,
Ryusuke Konishi