BUG at fs/afs/file.c:137!

Anton Blanchard anton at samba.org
Wed Aug 26 23:43:58 EDT 2009


Hi David,

> Can you try the attached patch please?

Thanks! With the attached patch I can no longer hit it.

Anton

> David
> ---
> From: David Howells <dhowells at redhat.com>
> Subject: [PATCH] AFS: Stop readlink() on AFS crashing because file not passed to afs_readpage()
> 
> kAFS crashes when asked to read a symbolic link because page_getlink() passes a
> NULL file pointer to read_mapping_page(), but afs_readpage() expects a file
> pointer from which to extract a key.
> 
> Modify afs_readpage() to request the appropriate key from the calling
> process's keyrings if a file struct is not supplied with one attached.
> 
> Signed-off-by: David Howells <dhowells at redhat.com>
> ---
> 
>  fs/afs/file.c |   18 +++++++++++++++---
>  1 files changed, 15 insertions(+), 3 deletions(-)
> 
> 
> diff --git a/fs/afs/file.c b/fs/afs/file.c
> index 1586496..cbc746d 100644
> --- a/fs/afs/file.c
> +++ b/fs/afs/file.c
> @@ -136,9 +136,16 @@ static int afs_readpage(struct file *file, struct page *page)
>  
>  	inode = page->mapping->host;
>  
> -	ASSERT(file != NULL);
> -	key = file->private_data;
> -	ASSERT(key != NULL);
> +	if (file) {
> +		key = file->private_data;
> +		ASSERT(key != NULL);
> +	} else {
> +		key = afs_request_key(AFS_FS_S(inode->i_sb)->volume->cell);
> +		if (IS_ERR(key)) {
> +			ret = PTR_ERR(key);
> +			goto error_nokey;
> +		}
> +	}
>  
>  	_enter("{%x},{%lu},{%lu}", key_serial(key), inode->i_ino, page->index);
>  
> @@ -209,12 +216,17 @@ static int afs_readpage(struct file *file, struct page *page)
>  		unlock_page(page);
>  	}
>  
> +	if (!file)
> +		key_put(key);
>  	_leave(" = 0");
>  	return 0;
>  
>  error:
>  	SetPageError(page);
>  	unlock_page(page);
> +	if (!file)
> +		key_put(key);
> +error_nokey:
>  	_leave(" = %d", ret);
>  	return ret;
>  }



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