Messages in this thread |  | | | Subject | Re: [PATCH] compat bug in sys_recvmsg, MSG_CMSG_COMPAT check missing | | From | Andreas Schwab <> | | Date | Sun, 06 Jun 2004 00:05:58 +0200 |
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"David S. Miller" <davem@redhat.com> writes:
> On Sat, 05 Jun 2004 23:47:22 +0200 > Andreas Schwab <schwab@suse.de> 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@suse.de SuSE Linux AG, Maxfeldstraße 5, 90409 Nürnberg, Germany Key fingerprint = 58CA 54C7 6D53 942B 1756 01D3 44D5 214B 8276 4ED5 "And now for something completely different." - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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