linux-kernel - Re: [patch] nfsd: oopses in cache

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Date:	Mon, 16 Jan 2012 10:50:31 -0500
From:	"J. Bruce Fields" <bfields@...ldses.org>
To:	Dan Carpenter <dan.carpenter@...cle.com>
Cc:	Sasha Levin <levinsasha928@...il.com>,
	linux-kernel@...r.kernel.org, Neil Brown <neilb@...e.de>,
	linux-nfs@...r.kernel.org
Subject: Re: [patch] nfsd: oopses in cache_parse()

On Mon, Jan 16, 2012 at 02:52:58PM +0300, Dan Carpenter wrote:
> We fixed expkey_parse() in b2ea70afad "nfsd: Fix oops when parsing a
> 0 length export" but there are other cache_parse() implimentations
> which have the same issue.
> 
> Signed-off-by: Dan Carpenter <dan.carpenter@...cle.com>
> ---
> Since half of the implimentations get this wrong, maybe we should
> just check for this in cache_do_downcall().  Is there ever a valid
> reason to pass a zero length string to cache_parse()?

I don't think so, no.  Checking in cache_do_downcall() sounds like a
good idea.

--b.

> 
> diff --git a/fs/nfsd/export.c b/fs/nfsd/export.c
> index cf8a6bd..1d147a8 100644
> --- a/fs/nfsd/export.c
> +++ b/fs/nfsd/export.c
> @@ -496,7 +496,7 @@ static int svc_export_parse(struct cache_detail *cd, char *mesg, int mlen)
>  	struct svc_export exp = {}, *expp;
>  	int an_int;
>  
> -	if (mesg[mlen-1] != '\n')
> +	if (mlen < 1 || mesg[mlen - 1] != '\n')
>  		return -EINVAL;
>  	mesg[mlen-1] = 0;
>  
> diff --git a/fs/nfs/dns_resolve.c b/fs/nfs/dns_resolve.c
> index a6e711a..d945d71 100644
> --- a/fs/nfs/dns_resolve.c
> +++ b/fs/nfs/dns_resolve.c
> @@ -217,7 +217,7 @@ static int nfs_dns_parse(struct cache_detail *cd, char *buf, int buflen)
>  	ssize_t len;
>  	int ret = -EINVAL;
>  
> -	if (buf[buflen-1] != '\n')
> +	if (buflen < 1 || buf[buflen - 1] != '\n')
>  		goto out;
>  	buf[buflen-1] = '\0';
>  
> diff --git a/fs/nfsd/nfs4idmap.c b/fs/nfsd/nfs4idmap.c
> index 9409627..f8456a4 100644
> --- a/fs/nfsd/nfs4idmap.c
> +++ b/fs/nfsd/nfs4idmap.c
> @@ -202,7 +202,7 @@ idtoname_parse(struct cache_detail *cd, char *buf, int buflen)
>  	int len;
>  	int error = -EINVAL;
>  
> -	if (buf[buflen - 1] != '\n')
> +	if (buflen < 1 || buf[buflen - 1] != '\n')
>  		return (-EINVAL);
>  	buf[buflen - 1]= '\0';
>  
> @@ -378,7 +378,7 @@ nametoid_parse(struct cache_detail *cd, char *buf, int buflen)
>  	char *buf1;
>  	int error = -EINVAL;
>  
> -	if (buf[buflen - 1] != '\n')
> +	if (buflen < 1 || buf[buflen - 1] != '\n')
>  		return (-EINVAL);
>  	buf[buflen - 1]= '\0';
>  
> 


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