[PATCH] fs: check pointer returned by get_fsdevice_by_path before dereferencing

[PATCH] fs: check pointer returned by get_fsdevice_by_path before dereferencing

[Gaël PORTAY]

In __canonicalize_path() we dereference the pointer returned by
get_fsdevice_by_path() without checking if the pointer is NULL or not.
When the pointer is NULL it leads to an Ooops.

	Ooops, address error on load or ifetch!

	$ 0   : 00000000 00000001 a0000026 a0811c10
	$ 4   : a0402e60 a0402e48 a0811c00 a0402e58
	$ 8   : 00000001 00000000 0000005a 00000023
	$12   : 00000000 00000002 00601021 00000000
	$16   : a0402e60 a0402e50 a0402e39 a0810000
	$20   : a0402e38 a0811420 a0811424 00000000
	$24   : 00000000 a080de10
	$28   : 87f87d40 a03ffa68 a0810000 a080ce30
	Hi    : 00000002
	Lo    : 00000000
	epc   : a080ce34
	ra    : a080ce30
	Status: 00000006
	Cause : 40008010
	Config: 80040483

	### ERROR ### Please RESET the board ###

Fixes: d79a81736 fs: Don't bother filesystems without link support with additional stat() calls

Signed-off-by: Gaël PORTAY <gael.portay@savoirfairelinux.com>
---
 fs/fs.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/fs.c b/fs/fs.c
index 88f0b1478..5135112c8 100644
--- a/fs/fs.c
+++ b/fs/fs.c
@@ -191,7 +191,7 @@ static char *__canonicalize_path(const char *_pathname, int level)
 		 * with an additional stat() call.
 		 */
 		fsdev = get_fsdevice_by_path(outpath);
-		if (!fsdev->driver->readlink)
+		if (!fsdev || !fsdev->driver->readlink)
 			continue;
 
 		ret = __lstat(outpath, &s);
-- 
2.16.1


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Re: [PATCH] fs: check pointer returned by get_fsdevice_by_path before dereferencing

[Sascha Hauer]

Hi Gaël,

On Sun, Mar 18, 2018 at 06:22:36PM -0400, Gaël PORTAY wrote:
> In __canonicalize_path() we dereference the pointer returned by
> get_fsdevice_by_path() without checking if the pointer is NULL or not.
> When the pointer is NULL it leads to an Ooops.
> 
> 	Ooops, address error on load or ifetch!
> 
> 	$ 0   : 00000000 00000001 a0000026 a0811c10
> 	$ 4   : a0402e60 a0402e48 a0811c00 a0402e58
> 	$ 8   : 00000001 00000000 0000005a 00000023
> 	$12   : 00000000 00000002 00601021 00000000
> 	$16   : a0402e60 a0402e50 a0402e39 a0810000
> 	$20   : a0402e38 a0811420 a0811424 00000000
> 	$24   : 00000000 a080de10
> 	$28   : 87f87d40 a03ffa68 a0810000 a080ce30
> 	Hi    : 00000002
> 	Lo    : 00000000
> 	epc   : a080ce34
> 	ra    : a080ce30
> 	Status: 00000006
> 	Cause : 40008010
> 	Config: 80040483
> 
> 	### ERROR ### Please RESET the board ###
> 
> Fixes: d79a81736 fs: Don't bother filesystems without link support with additional stat() calls
> 
> Signed-off-by: Gaël PORTAY <gael.portay@savoirfairelinux.com>
> ---
>  fs/fs.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)

Applied, thanks.

I wonder though what calls into the filesystem layer before / is
mounted in your case.

Sascha


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Re: [PATCH] fs: check pointer returned by get_fsdevice_by_path before dereferencing

[Gaël PORTAY]

Hi Sascha,

On Mon, Mar 19, 2018 at 09:36:29AM +0100, Sascha Hauer wrote:
> ...
> I wonder though what calls into the filesystem layer before / is
> mounted in your case.
>

The issue is trigger by function stat() in start_barebox(), right before
I expect to have a shell.

Here.

	if (IS_ENABLED(CONFIG_COMMAND_SUPPORT)) {
		pr_info("running /env/bin/init...\n");

		if (!stat("/env/bin/init", &s))
			run_command("source /env/bin/init");
		else
			pr_err("/env/bin/init not found\n");
	}

My configuration is very minimal for now. I do not have (yet) any FS
selected (excepted devfs) and I do not have any root device mounted
either in this configuration.

I guess this is why fs_dev_root is NULL and why get_fsdevice_by_path()
returns fs_dev_root (because there is nothing to iterate in list
fs_device_list).

Gael

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Re: [PATCH] fs: check pointer returned by get_fsdevice_by_path before dereferencing

[Antony Pavlov]

On Sun, 18 Mar 2018 18:22:36 -0400
Gaël PORTAY <gael.portay@savoirfairelinux.com> wrote:

> In __canonicalize_path() we dereference the pointer returned by
> get_fsdevice_by_path() without checking if the pointer is NULL or not.
> When the pointer is NULL it leads to an Ooops.
> 
> 	Ooops, address error on load or ifetch!
> 
> 	$ 0   : 00000000 00000001 a0000026 a0811c10
> 	$ 4   : a0402e60 a0402e48 a0811c00 a0402e58
> 	$ 8   : 00000001 00000000 0000005a 00000023
> 	$12   : 00000000 00000002 00601021 00000000
> 	$16   : a0402e60 a0402e50 a0402e39 a0810000
> 	$20   : a0402e38 a0811420 a0811424 00000000
> 	$24   : 00000000 a080de10
> 	$28   : 87f87d40 a03ffa68 a0810000 a080ce30
> 	Hi    : 00000002
> 	Lo    : 00000000
> 	epc   : a080ce34

Salut Gaël!

It looks like you use MIPS board.
Your epc == 0xa080ce34 is inside KSEG1 region (uncached memory).
May be there is no cache support in current barebox for your CPU.
Which CPU core you use?

Très cordialement,
  Antony Pavlov

> 	ra    : a080ce30
> 	Status: 00000006
> 	Cause : 40008010
> 	Config: 80040483
> 
> 	### ERROR ### Please RESET the board ###
> 
> Fixes: d79a81736 fs: Don't bother filesystems without link support with additional stat() calls
> 
> Signed-off-by: Gaël PORTAY <gael.portay@savoirfairelinux.com>
> ---
>  fs/fs.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/fs/fs.c b/fs/fs.c
> index 88f0b1478..5135112c8 100644
> --- a/fs/fs.c
> +++ b/fs/fs.c
> @@ -191,7 +191,7 @@ static char *__canonicalize_path(const char *_pathname, int level)
>  		 * with an additional stat() call.
>  		 */
>  		fsdev = get_fsdevice_by_path(outpath);
> -		if (!fsdev->driver->readlink)
> +		if (!fsdev || !fsdev->driver->readlink)
>  			continue;
>  
>  		ret = __lstat(outpath, &s);
> -- 
> 2.16.1
> 
> 
> _______________________________________________
> barebox mailing list
> barebox@lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/barebox


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