[U-Boot] [PATCH] fs: ext4: Prevent infinite loop in ext4fs_iterate_dir

[U-Boot] [PATCH] fs: ext4: Prevent infinite loop in ext4fs_iterate_dir

[Thomas Fitzsimmons]

If the ext3 journal gets out of sync with what is written on disk, for
example because of an unexpected power cut, ext4fs_read_file can
return an all-zero directory entry.  In that case, ext4fs_iterate_dir
would infinite loop.

This patch detects when a directory entry's direntlen member is 0 and
returns a failure status, which breaks out of the infinite loop.  As a
result, U-Boot will not find files that may subsequently be recovered
when the journal is replayed.

This is better behaviour than hanging in an infinite loop, but as a
further improvement maybe U-Boot could interpret the ext3 journal and
actually find the unsynced entries.

Signed-off-by: Thomas Fitzsimmons <fitzsim@cisco.com>
---
 fs/ext4/ext4_common.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/fs/ext4/ext4_common.c b/fs/ext4/ext4_common.c
index 727a2f7..e73223a 100644
--- a/fs/ext4/ext4_common.c
+++ b/fs/ext4/ext4_common.c
@@ -1920,6 +1920,11 @@ int ext4fs_iterate_dir(struct ext2fs_node *dir, char *name,
 		if (status < 0)
 			return 0;
 
+		if (dirent.direntlen == 0) {
+			printf("Failed to iterate over directory %s\n", name);
+			return 0;
+		}
+
 		if (dirent.namelen != 0) {
 			char filename[dirent.namelen + 1];
 			struct ext2fs_node *fdiro;
-- 
1.8.3.1

[U-Boot] [PATCH] fs: ext4: Prevent infinite loop in ext4fs_iterate_dir

[Stefan Roese]

Hi Thomas,

On 18.11.2015 18:42, Thomas Fitzsimmons wrote:
> If the ext3 journal gets out of sync with what is written on disk, for
> example because of an unexpected power cut, ext4fs_read_file can
> return an all-zero directory entry.  In that case, ext4fs_iterate_dir
> would infinite loop.
>
> This patch detects when a directory entry's direntlen member is 0 and
> returns a failure status, which breaks out of the infinite loop.  As a
> result, U-Boot will not find files that may subsequently be recovered
> when the journal is replayed.
>
> This is better behaviour than hanging in an infinite loop, but as a
> further improvement maybe U-Boot could interpret the ext3 journal and
> actually find the unsynced entries.
>
> Signed-off-by: Thomas Fitzsimmons <fitzsim@cisco.com>
> ---
>   fs/ext4/ext4_common.c | 5 +++++
>   1 file changed, 5 insertions(+)
>
> diff --git a/fs/ext4/ext4_common.c b/fs/ext4/ext4_common.c
> index 727a2f7..e73223a 100644
> --- a/fs/ext4/ext4_common.c
> +++ b/fs/ext4/ext4_common.c
> @@ -1920,6 +1920,11 @@ int ext4fs_iterate_dir(struct ext2fs_node *dir, char *name,
>   		if (status < 0)
>   			return 0;
>
> +		if (dirent.direntlen == 0) {
> +			printf("Failed to iterate over directory %s\n", name);
> +			return 0;
> +		}
> +
>   		if (dirent.namelen != 0) {
>   			char filename[dirent.namelen + 1];
>   			struct ext2fs_node *fdiro;
>

Reviewed-by: Stefan Roese <sr@denx.de>

Thanks,
Stefan

[U-Boot] fs: ext4: Prevent infinite loop in ext4fs_iterate_dir

[Tom Rini]

On Wed, Nov 18, 2015 at 12:42:53PM -0500, Thomas Fitzsimmons wrote:

> If the ext3 journal gets out of sync with what is written on disk, for
> example because of an unexpected power cut, ext4fs_read_file can
> return an all-zero directory entry.  In that case, ext4fs_iterate_dir
> would infinite loop.
> 
> This patch detects when a directory entry's direntlen member is 0 and
> returns a failure status, which breaks out of the infinite loop.  As a
> result, U-Boot will not find files that may subsequently be recovered
> when the journal is replayed.
> 
> This is better behaviour than hanging in an infinite loop, but as a
> further improvement maybe U-Boot could interpret the ext3 journal and
> actually find the unsynced entries.
> 
> Signed-off-by: Thomas Fitzsimmons <fitzsim@cisco.com>
> Reviewed-by: Stefan Roese <sr@denx.de>

Applied to u-boot/master, thanks!

-- 
Tom
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