Commit 09b871ffd4 (parisc: Define access_ok() as macro) missed to mark uaddr
as used, which then gives compiler warnings about unused variables.
Fix it by comparing uaddr to uaddr which then gets optimized away by the
compiler.
Signed-off-by: Helge Deller <deller@gmx.de>
Fixes: 09b871ffd4 ("parisc: Define access_ok() as macro")
Define access_ok() as macro instead of static function. This fixes build
warnings in code where the second parameter is given as unsigned long.
Signed-off-by: Helge Deller <deller@gmx.de>
Pull uaccess fixes from Al Viro:
"Fixes for broken uaccess primitives - mostly lack of proper zeroing
in copy_from_user()/get_user()/__get_user(), but for several
architectures there's more (broken clear_user() on frv and
strncpy_from_user() on hexagon)"
* 'uaccess-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (28 commits)
avr32: fix copy_from_user()
microblaze: fix __get_user()
microblaze: fix copy_from_user()
m32r: fix __get_user()
blackfin: fix copy_from_user()
sparc32: fix copy_from_user()
sh: fix copy_from_user()
sh64: failing __get_user() should zero
score: fix copy_from_user() and friends
score: fix __get_user/get_user
s390: get_user() should zero on failure
ppc32: fix copy_from_user()
parisc: fix copy_from_user()
openrisc: fix copy_from_user()
nios2: fix __get_user()
nios2: copy_from_user() should zero the tail of destination
mn10300: copy_from_user() should zero on access_ok() failure...
mn10300: failing __get_user() and get_user() should zero
mips: copy_from_user() must zero the destination on access_ok() failure
ARC: uaccess: get_user to zero out dest in cause of fault
...
There are three usercopy warnings which are currently being silenced for
gcc 4.6 and newer:
1) "copy_from_user() buffer size is too small" compile warning/error
This is a static warning which happens when object size and copy size
are both const, and copy size > object size. I didn't see any false
positives for this one. So the function warning attribute seems to
be working fine here.
Note this scenario is always a bug and so I think it should be
changed to *always* be an error, regardless of
CONFIG_DEBUG_STRICT_USER_COPY_CHECKS.
2) "copy_from_user() buffer size is not provably correct" compile warning
This is another static warning which happens when I enable
__compiletime_object_size() for new compilers (and
CONFIG_DEBUG_STRICT_USER_COPY_CHECKS). It happens when object size
is const, but copy size is *not*. In this case there's no way to
compare the two at build time, so it gives the warning. (Note the
warning is a byproduct of the fact that gcc has no way of knowing
whether the overflow function will be called, so the call isn't dead
code and the warning attribute is activated.)
So this warning seems to only indicate "this is an unusual pattern,
maybe you should check it out" rather than "this is a bug".
I get 102(!) of these warnings with allyesconfig and the
__compiletime_object_size() gcc check removed. I don't know if there
are any real bugs hiding in there, but from looking at a small
sample, I didn't see any. According to Kees, it does sometimes find
real bugs. But the false positive rate seems high.
3) "Buffer overflow detected" runtime warning
This is a runtime warning where object size is const, and copy size >
object size.
All three warnings (both static and runtime) were completely disabled
for gcc 4.6 with the following commit:
2fb0815c9e ("gcc4: disable __compiletime_object_size for GCC 4.6+")
That commit mistakenly assumed that the false positives were caused by a
gcc bug in __compiletime_object_size(). But in fact,
__compiletime_object_size() seems to be working fine. The false
positives were instead triggered by #2 above. (Though I don't have an
explanation for why the warnings supposedly only started showing up in
gcc 4.6.)
So remove warning #2 to get rid of all the false positives, and re-enable
warnings #1 and #3 by reverting the above commit.
Furthermore, since #1 is a real bug which is detected at compile time,
upgrade it to always be an error.
Having done all that, CONFIG_DEBUG_STRICT_USER_COPY_CHECKS is no longer
needed.
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: "H . Peter Anvin" <hpa@zytor.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Byungchul Park <byungchul.park@lge.com>
Cc: Nilay Vaish <nilayvaish@gmail.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This patch simplifies the code for get_user() and put_user() a lot.
Instead of accessing kernel memory (%sr0) and userspace memory (%sr3)
hard-coded in the assembler instruction, we now preload %sr2 with either
%sr0 (for accessing KERNEL_DS) or with sr3 (to access USER_DS) and
use %sr2 in the load directly.
The generated code avoids a branch and speeds up execution by generating
less assembler instructions.
Signed-off-by: Helge Deller <deller@gmx.de>
Tested-by: Rolf Eike Beer <eike-kernel@sf-tec.de>
Update the comment to reflect the changes of commit 0de7985 (parisc: Use
generic extable search and sort routines).
Signed-off-by: Helge Deller <deller@gmx.de>
Handling exceptions from modules never worked on parisc.
It was just masked by the fact that exceptions from modules
don't happen during normal use.
When a module triggers an exception in get_user() we need to load the
main kernel dp value before accessing the exception_data structure, and
afterwards restore the original dp value of the module on exit.
Noticed-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Helge Deller <deller@gmx.de>
Cc: stable@vger.kernel.org
Switch to the generic extable search and sort routines which were introduced
with commit a272858 from Ard Biesheuvel. This saves quite some memory in the
vmlinux binary with the 64bit kernel.
Signed-off-by: Helge Deller <deller@gmx.de>
While working on arch/parisc/include/asm/uaccess.h, I noticed that some
macros within this header are made harder to read because they violate a
coding style rule: space is missing after comma.
Fix it up.
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Helge Deller <deller@gmx.de>
virtio wants to read bitwise types from userspace using get_user. At the
moment this triggers sparse errors, since the value is passed through an
integer.
Fix that up using __force.
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: Helge Deller <deller@gmx.de>
Signed-off-by: Helge Deller <deller@gmx.de>
This reverts commit 63379c1353.
It broke userspace and adding more checking is not needed.
Even checking if a syscall would access memory in page zero doesn't
makes sense since it may lead to some syscalls returning -EFAULT
where we would return other error codes on other platforms.
In summary, just drop this change and return to always return 1.
Signed-off-by: Helge Deller <deller@gmx.de>
Up to now PA-RISC could live with a trivial version of access_ok().
Our fault handlers can correctly handle fault cases.
But testcases showed that we need a better access check else we won't
always return correct errno failure codes to userspace.
Problem showed up during 32bit userspace tests in which writev() used a
32bit memory area and length which would then wrap around on 64bit
kernel.
Signed-off-by: Helge Deller <deller@gmx.de>
Provide a macro ASM_EXCEPTIONTABLE_ENTRY() to create exception table
entries and convert all open-coded places to use that macro.
This patch is a first step toward creating a exception table which only
holds 32bit pointers even on a 64bit kernel. That way in my own kernel
I was able to reduce the in-kernel exception table from 44kB to 22kB.
Signed-off-by: Helge Deller <deller@gmx.de>
When targetting 32-bit processors, __put_user emits a pair of stw
instructions for the 8-byte case. If the type of __val is a pointer, the
marshalling code casts it to the wider integer type of u64, resulting
in the following compiler warnings:
kernel/signal.c: In function 'copy_siginfo_to_user':
kernel/signal.c:2752:11: warning: cast from pointer to integer of different size [-Wpointer-to-int-cast]
kernel/signal.c:2752:11: warning: cast from pointer to integer of different size [-Wpointer-to-int-cast]
[...]
This patch fixes the warnings by removing the marshalling code and using
the correct output modifiers in the __put_{user,kernel}_asm64 macros
so that GCC will allocate the right registers without the need to
extract the two words explicitly.
Cc: Helge Deller <deller@gmx.de>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Helge Deller <deller@gmx.de>
Add CONFIG_DEBUG_STRICT_USER_COPY_CHECKS, copied from the x86
implementation. Tested with 32 and 64bit kernel.
Signed-off-by: Helge Deller <deller@gmx.de>
Signed-off-by: Kyle McMartin <kyle@mcmartin.ca>
The current asm-generic/page.h only contains the get_order
function, and asm-generic/uaccess.h only implements
unaligned accesses. This renames the file to getorder.h
and uaccess-unaligned.h to make room for new page.h
and uaccess.h file that will be usable by all simple
(e.g. nommu) architectures.
Signed-off-by: Remis Lima Baima <remis.developer@googlemail.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Fix those compile warnings:
uaccess.h:244: warning: `struct pt_regs' declared inside parameter list
uaccess.h:244: warning: its scope is only this definition or declaration, which is probably not what you want
Signed-off-by: Helge Deller <deller@gmx.de>
Signed-off-by: Kyle McMartin <kyle@mcmartin.ca>
On Wed, Dec 17, 2008 at 11:46:05PM +0100, Helge Deller wrote:
>
Honestly, I can't decide whether to apply this. It really should never
happen in the kernel, since the kernel can guarantee it won't get the
access rights failure (highest privilege level, and can set %sr and
%protid to whatever it wants.)
It really genuinely is a bug that probably should panic the kernel. The
only precedent I can easily see is x86 fixing up a bad iret with a
general protection fault, which is more or less analogous to code 27
here.
On the other hand, taking the exception on a userspace access really
isn't all that critical, and there's fundamentally little reason for the
kernel not to SIGSEGV the process, and continue...
Argh.
(btw, I've instrumented my do_sys_poll with a pile of assertions that
%cr8 << 1 == %sr3 == current->mm.context... let's see if where we're
getting corrupted is deterministic, though, I would guess that it won't
be.)
Signed-off-by: Kyle McMartin <kyle@mcmartin.ca>
