From: Chen Gang <gang.chen@asianux•com>
To: Ben Hutchings <bhutchings@solarflare•com>
Cc: David Miller <davem@davemloft•net>,
"dhowells@redhat•com" <dhowells@redhat•com>,
"Eric W. Biederman" <ebiederm@xmission•com>,
Rusty Russell <rusty@rustcorp•com.au>,
Serge Hallyn <serge.hallyn@canonical•com>,
netdev <netdev@vger•kernel.org>
Subject: Re: [PATCH] Net: rxrpc: signed and unsigned issue, need type cast for n_elem.
Date: Tue, 23 Apr 2013 09:24:48 +0800 [thread overview]
Message-ID: <5175E2E0.1030901@asianux.com> (raw)
In-Reply-To: <1366659281.4016.7.camel@bwh-desktop.uk.solarflarecom.com>
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 --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) {
----------------------diff end--------------------------------------------------
> Ben.
>
>> return -EINVAL;
>> *_n_elem = n_elem;
>> if (n_elem > 0) {
>
--
Chen Gang
Asianux Corporation
prev parent reply other threads:[~2013-04-23 1:25 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-04-22 10:24 [PATCH] Net: rxrpc: signed and unsigned issue, need type cast for n_elem Chen Gang
2013-04-22 19:34 ` Ben Hutchings
2013-04-23 1:24 ` Chen Gang [this message]
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