(cc in Eitan as he may be interested in the extra restrict cases)
On 02/03/2018 11:47, Konstantin Belousov wrote:
Author: kib
Date: Fri Mar 2 16:47:02 2018
New Revision: 330285
URL: https://svnweb.freebsd.org/changeset/base/330285
Log:
Remove _Nonnull attributes from user addresses arguments for
copyout(9) family.
The addresses are user-controllable, and if the process ABI allows
mapping at zero, then the zero address is meaningful, contradicting
the definition of _Nonnull. In any case, it does not require any
special code to handle NULL udaddr.
FWIW, the _Nonnull attributes didn't do much at all beyond producing a
warning.
They replaced the GNU __nonnull() attributes which were much more dangerous.
I am OK with seeing both gone here though.
It is not clear if __restrict makes sense as well, since kaddr and
udaddr point to different address spaces, so equal numeric values of
the pointers do not imply aliasing and a legitimate. But leave it for
later.
copyinstr(9) does not have its user address argument annotated.
I think use of _Nonnull attributes in the threading functions may also
be a waste (I introduced them mostly to be compatible with Android).
FWIW, Dragonfly sprinkled some restrict there recently:
http://gitweb.dragonflybsd.org/dragonfly.git/commit/d33005aaee6af52c80428b59b52aee522c002492
Just in case someone is considering more cleanups.
Cheers,
Pedro.
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
Modified:
head/sys/sys/systm.h
Modified: head/sys/sys/systm.h
==============================================================================
--- head/sys/sys/systm.h Fri Mar 2 16:31:23 2018 (r330284)
+++ head/sys/sys/systm.h Fri Mar 2 16:47:02 2018 (r330285)
@@ -277,14 +277,14 @@ int copystr(const void * _Nonnull __restrict kfaddr,
int copyinstr(const void * __restrict udaddr,
void * _Nonnull __restrict kaddr, size_t len,
size_t * __restrict lencopied);
-int copyin(const void * _Nonnull __restrict udaddr,
+int copyin(const void * __restrict udaddr,
void * _Nonnull __restrict kaddr, size_t len);
-int copyin_nofault(const void * _Nonnull __restrict udaddr,
+int copyin_nofault(const void * __restrict udaddr,
void * _Nonnull __restrict kaddr, size_t len);
int copyout(const void * _Nonnull __restrict kaddr,
- void * _Nonnull __restrict udaddr, size_t len);
+ void * __restrict udaddr, size_t len);
int copyout_nofault(const void * _Nonnull __restrict kaddr,
- void * _Nonnull __restrict udaddr, size_t len);
+ void * __restrict udaddr, size_t len);
int fubyte(volatile const void *base);
long fuword(volatile const void *base);
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