Patchwork Net: rxrpc: signed and unsigned issue, need type cast for n_elem.

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Submitter Chen Gang
Date April 23, 2013, 1:24 a.m.
Message ID <5175E2E0.1030901@asianux.com>
Download mbox | patch
Permalink /patch/238704/
State RFC
Delegated to: David Miller
Headers show

Comments

Chen Gang - April 23, 2013, 1:24 a.m.
On 2013年04月23日 03:34, Ben Hutchings wrote:
> On Mon, 2013-04-22 at 18:24 +0800, Chen Gang wrote:
>> n_elem is unsigned int which never < 0.
>>   but it seems, we realy need check it whether < 0.
>>   so need a type cast for it.
>>
>>   find it by EXTRA_CFLAGS=-W
>>
>>
>> Signed-off-by: Chen Gang <gang.chen@asianux.com>
>> ---
>>  net/rxrpc/ar-key.c |    2 +-
>>  1 files changed, 1 insertions(+), 1 deletions(-)
>>
>> diff --git a/net/rxrpc/ar-key.c b/net/rxrpc/ar-key.c
>> index 7633a75..ba0b722 100644
>> --- a/net/rxrpc/ar-key.c
>> +++ b/net/rxrpc/ar-key.c
>> @@ -346,7 +346,7 @@ static int rxrpc_krb5_decode_tagged_array(struct krb5_tagged_data **_td,
>>  
>>  	n_elem = ntohl(*xdr++);
>>  	toklen -= 4;
>> -	if (n_elem < 0 || n_elem > max_n_elem)
>> +	if ((int)n_elem < 0 || n_elem > max_n_elem)
> 
> (int)n_elem < 0 is equivalent to n_elem >= 0x80000000, and if that is
> true then n_elem > max_n_elem (because max_n_elem <= 0xff).
> 

  ok, thanks, my subject and the comments are incorrect.

  but I still prefer to improve the original code like below.
    (also need change the subject and the comments)

----------------------diff begin------------------------------------------------


----------------------diff end--------------------------------------------------

> Ben.
> 
>>  		return -EINVAL;
>>  	*_n_elem = n_elem;
>>  	if (n_elem > 0) {
>

Patch

diff --git a/net/rxrpc/ar-key.c b/net/rxrpc/ar-key.c
index 7633a75..cde682f 100644
--- a/net/rxrpc/ar-key.c
+++ b/net/rxrpc/ar-key.c
@@ -346,7 +346,7 @@  static int rxrpc_krb5_decode_tagged_array(struct krb5_tagged_data **_td,
 
 	n_elem = ntohl(*xdr++);
 	toklen -= 4;
-	if (n_elem < 0 || n_elem > max_n_elem)
+	if (n_elem > max_n_elem)
 		return -EINVAL;
 	*_n_elem = n_elem;
 	if (n_elem > 0) {