mm/gup.c provides a kernel interface that accepts user addresses and
manipulates user pages directly (for example get_user_pages, that is used
by the futex syscall). Here we also need to handle the case of tagged user
pointers.
Untag addresses passed to this interface.
Signed-off-by: Andrey Konov
This patch makes the untagged_addr macro accept all kinds of address types
(void *, unsigned long, etc.) and allows not to specify type casts in each
place where it is used. This is done by using __typeof__.
Signed-off-by: Andrey Konovalov
---
arch/arm64/include/asm/uaccess.h | 3 ++-
1 file cha
copy_from_user (and a few other similar functions) are used to copy data
from user memory into the kernel memory or vice versa. Since a user can
provided a tagged pointer to one of the syscalls that use copy_from_user,
we need to correctly handle such pointers.
Do this by untagging user pointers i
Memory subsystem syscalls accept user addresses as arguments, but don't use
copy_from_user and other similar functions, so we need to handle this case
separately.
Untag user pointers passed to madvise, mbind, get_mempolicy, mincore,
mlock, mlock2, brk, mmap_pgoff, old_mmap, munmap, remap_file_page
strncpy_from_user and strnlen_user accept user addresses as arguments, and
do not go through the same path as copy_from_user and others, so here we
need to separately handle the case of tagged user addresses as well.
Untag user pointers passed to these functions.
Signed-off-by: Andrey Konovalov
To allow arm64 syscalls accept tagged pointers from userspace, we must
untag them when they are passed to the kernel. Since untagging is done in
generic parts of the kernel (like the mm subsystem), the untagged_addr
macro should be defined for all architectures.
Define it as a noop for all other a
arm64 has a feature called Top Byte Ignore, which allows to embed pointer
tags into the top byte of each pointer. Userspace programs (such as
HWASan, a memory debugging tool [1]) might use this feature and pass
tagged user pointers to the kernel through syscalls or other interfaces.
This patch mak
On Fri, Mar 9, 2018 at 3:02 PM, Andrey Konovalov wrote:
> To allow arm64 syscalls accept tagged pointers from userspace, we must
> untag them when they are passed to the kernel. Since untagging is done in
> generic parts of the kernel (like the mm subsystem), the untagged_addr
> macro should be de
Hi Andrey,
On 09/03/18 14:01, Andrey Konovalov wrote:
arm64 has a feature called Top Byte Ignore, which allows to embed pointer
tags into the top byte of each pointer. Userspace programs (such as
HWASan, a memory debugging tool [1]) might use this feature and pass
tagged user pointers to the ker
On 09/03/18 14:02, Andrey Konovalov wrote:
To allow arm64 syscalls accept tagged pointers from userspace, we must
untag them when they are passed to the kernel. Since untagging is done in
generic parts of the kernel (like the mm subsystem), the untagged_addr
macro should be defined for all archit
On Fri, Mar 9, 2018 at 3:16 PM, Robin Murphy wrote:
> On 09/03/18 14:02, Andrey Konovalov wrote:
>>
>> To allow arm64 syscalls accept tagged pointers from userspace, we must
>> untag them when they are passed to the kernel. Since untagging is done in
>> generic parts of the kernel (like the mm sub
On Fri, Mar 9, 2018 at 3:15 PM, Robin Murphy wrote:
> Hi Andrey,
>
> On 09/03/18 14:01, Andrey Konovalov wrote:
>>
>> arm64 has a feature called Top Byte Ignore, which allows to embed pointer
>> tags into the top byte of each pointer. Userspace programs (such as
>> HWASan, a memory debugging tool
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