"David S. Miller" <davem@xxxxxxxxxx> writes:
> On Sat, 05 Jun 2004 23:47:22 +0200
> Andreas Schwab <schwab@xxxxxxx> wrote:
>
>> > Olaf's patch, it said:
>> >
>> > - if (flags & ~(MSG_PEEK|MSG_DONTWAIT|MSG_TRUNC))
>> > + if (flags & ~(MSG_PEEK|MSG_DONTWAIT|MSG_TRUNC|MSG_CMSG_COMPAT))
>>
>> Yes, and where is the problem?
>
> If MSG_CMSG_COMPAT is "ZERO", which it will be if CONFIG_COMPAT is
> not set, then "~0" is all bits, therefore if any bit (even the ones
> we want to accept) is set we will return failure. The test ends
> up amounting to:
>
> if (flags & ~0)
>
> which is true if any bit is set, that's not what we want.
Can you say DeMorgan?
> diff -Nru a/include/linux/socket.h b/include/linux/socket.h
> --- a/include/linux/socket.h 2004-06-05 14:53:34 -07:00
> +++ b/include/linux/socket.h 2004-06-05 14:53:34 -07:00
> @@ -241,8 +241,10 @@
>
> #if defined(CONFIG_COMPAT)
> #define MSG_CMSG_COMPAT 0x80000000 /* This message needs 32 bit
> fixups */
> +#define MSG_FLAGS_USER(X) ((X) & ~MSG_CMSG_COMPAT)
> #else
> #define MSG_CMSG_COMPAT 0 /* We never have 32 bit fixups
> */
> +#define MSG_FLAGS_USER(X) (X)
> #endif
>
>
> diff -Nru a/net/appletalk/ddp.c b/net/appletalk/ddp.c
> --- a/net/appletalk/ddp.c 2004-06-05 14:53:35 -07:00
> +++ b/net/appletalk/ddp.c 2004-06-05 14:53:35 -07:00
> @@ -1567,7 +1567,7 @@
> struct atalk_route *rt;
> int err;
>
> - if (flags & ~MSG_DONTWAIT)
> + if (MSG_FLAGS_USER(flags) & ~MSG_DONTWAIT)
> return -EINVAL;
>
> if (len > DDP_MAXSZ)
This is exactly equivalent to Olaf's version.
Andreas.
--
Andreas Schwab, SuSE Labs, schwab@xxxxxxx
SuSE Linux AG, Maxfeldstraße 5, 90409 Nürnberg, Germany
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"And now for something completely different."
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