linux-kernel - Re: [PATCH] Propagate CRAMFS uncompression errors

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <1234238761.17414.2.camel@cuplxvomd02.corp.sa.net>
Date:	Mon, 09 Feb 2009 20:06:01 -0800
From:	David VomLehn <dvomlehn@...co.com>
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] Propagate CRAMFS uncompression errors


On Mon, 2009-02-09 at 19:48 -0800, Andrew Morton wrote:
...
> 
> umm...
> 
> Nope, it's still not right.  We'll treat this case:
> 
> 		if (compr_len == 0)
> 			; /* hole */
> 
> as an IO error.  grr.
> 
> --- a/fs/cramfs/inode.c~cramfs-propagate-uncompression-errors
> +++ a/fs/cramfs/inode.c
> @@ -477,7 +477,7 @@ static int cramfs_readpage(struct file *
>  		mutex_unlock(&read_mutex);
>  		pgdata = kmap(page);
>  		if (compr_len == 0)
> -			; /* hole */
> +			goto out; /* hole */
>  		else if (compr_len > (PAGE_CACHE_SIZE << 1))
>  			printk(KERN_ERR "cramfs: bad compressed blocksize %u\n", compr_len);
>  		else {
> @@ -488,12 +488,20 @@ static int cramfs_readpage(struct file *
>  				 compr_len);
>  			mutex_unlock(&read_mutex);
>  		}
> -	} else
> -		pgdata = kmap(page);
> -	memset(pgdata + bytes_filled, 0, PAGE_CACHE_SIZE - bytes_filled);
> -	kunmap(page);
> -	flush_dcache_page(page);
> -	SetPageUptodate(page);
> +
> +		if (bytes_filled == 0) {
> +			/* Decompression error */
> +			ClearPageUptodate(page);
> +			SetPageError(page);
> +		} else {
> +			memset(pgdata + bytes_filled, 0,
> +					PAGE_CACHE_SIZE - bytes_filled);
> +			flush_dcache_page(page);
> +			SetPageUptodate(page);
> +		}
> +		kunmap(page);
> +	}
> +out:
>  	unlock_page(page);
>  	return 0;
>  }

Is that actually an error. The comment in the code is, uh, a bit terse,
but I took it to mean that there was a deliberate hole, just like holes
in files that should read as all zeroes. But even if it's actually an
error, we still need to kunmap the page
-- 
David VomLehn, dvomlehn@...co.com




     - - - - -                              Cisco                            - - - - -         
This e-mail and any attachments may contain information which is confidential, 
proprietary, privileged or otherwise protected by law. The information is solely 
intended for the named addressee (or a person responsible for delivering it to 
the addressee). If you are not the intended recipient of this message, you are 
not authorized to read, print, retain, copy or disseminate this message or any 
part of it. If you have received this e-mail in error, please notify the sender 
immediately by return e-mail and delete it from your computer.

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/