linux-kernel - Re: [PATCH] nfsd: wrong index used in inner loop

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Message-ID: <4D79A183.8090306@cn.fujitsu.com>
Date:	Fri, 11 Mar 2011 12:13:55 +0800
From:	Mi Jinlong <mijinlong@...fujitsu.com>
To:	"J. Bruce Fields" <bfields@...ldses.org>
CC:	roel <roel.kluin@...il.com>, Neil Brown <neilb@...e.de>,
	linux-nfs@...r.kernel.org,
	Andrew Morton <akpm@...ux-foundation.org>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] nfsd: wrong index used in inner loop



J. Bruce Fields:
> On Tue, Mar 08, 2011 at 10:32:26PM +0100, roel wrote:
>> Index i was already used in the outer loop
>>
>> Signed-off-by: Roel Kluin <roel.kluin@...il.com>
>> ---
>>  fs/nfsd/nfs4xdr.c |    4 ++--
>>  1 files changed, 2 insertions(+), 2 deletions(-)
>>
>> Not 100% sure this one is needed but it looks suspicious.
> 
> Looks bad to me, thanks.
> 
> nfsd4_decode_create_session should probably really be broken up a little
> bit; if it wasn't so long this would have been more obvious.
> 
> I'll see if I can slip this into 2.6.38 with a couple other last-minute
> patches....  Otherwise, it'll be in 2.6.39.
> 
> --b.
> 
>> diff --git a/fs/nfsd/nfs4xdr.c b/fs/nfsd/nfs4xdr.c
>> index 1275b86..615f0a9 100644
>> --- a/fs/nfsd/nfs4xdr.c
>> +++ b/fs/nfsd/nfs4xdr.c
>> @@ -1142,7 +1142,7 @@ nfsd4_decode_create_session(struct nfsd4_compoundargs *argp,
>>  
>>  	u32 dummy;
>>  	char *machine_name;
>> -	int i;
>> +	int i, j;
>>  	int nr_secflavs;
>>  
>>  	READ_BUF(16);
>> @@ -1215,7 +1215,7 @@ nfsd4_decode_create_session(struct nfsd4_compoundargs *argp,
>>  			READ_BUF(4);
>>  			READ32(dummy);
>>  			READ_BUF(dummy * 4);
>> -			for (i = 0; i < dummy; ++i)
>> +			for (j = 0; j < dummy; ++j)
>>  				READ32(dummy);

  We must not use dummy for index here.
  After the first index, READ32(dummy) will change dummy!!!!

  The following patch fix this problem.

--
thanks,
Mi Jinlong
============================================================

We must not use dummy for index.
After the first index, READ32(dummy) will change dummy!!!!

Signed-off-by: Mi Jinlong <mijinlong@...fujitsu.com>
---
 fs/nfsd/nfs4xdr.c |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/fs/nfsd/nfs4xdr.c b/fs/nfsd/nfs4xdr.c
index 615f0a9..8dd70d0 100644
--- a/fs/nfsd/nfs4xdr.c
+++ b/fs/nfsd/nfs4xdr.c
@@ -1140,7 +1140,7 @@ nfsd4_decode_create_session(struct nfsd4_compoundargs *argp,
 {
 	DECODE_HEAD;
 
-	u32 dummy;
+	u32 dummy, tmp;
 	char *machine_name;
 	int i, j;
 	int nr_secflavs;
@@ -1216,7 +1216,7 @@ nfsd4_decode_create_session(struct nfsd4_compoundargs *argp,
 			READ32(dummy);
 			READ_BUF(dummy * 4);
 			for (j = 0; j < dummy; ++j)
-				READ32(dummy);
+				READ32(tmp);
 			break;
 		case RPC_AUTH_GSS:
 			dprintk("RPC_AUTH_GSS callback secflavor "
-- 
1.7.4.1


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