[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 at 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 at 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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