xiaomi-sm8450/android_kernel_xiaomi_sm8450
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

x86: remove address space overrides using set_fs()

Browse Source 
Stop providing the possibility to override the address space using
set_fs() now that there is no need for that any more.  To properly
handle the TASK_SIZE_MAX checking for 4 vs 5-level page tables on
x86 a new alternative is introduced, which just like the one in
entry_64.S has to use the hardcoded virtual address bits to escape
the fact that TASK_SIZE_MAX isn't actually a constant when 5-level
page tables are enabled.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Christoph Hellwig
2020-09-03 16:22:40 +02:00
committed by Al Viro
parent a1d826d475
commit 47058bb54b
8 changed files with 39 additions and 77 deletions
Download Patch File Download Diff File Expand all files Collapse all files

26
arch/x86/include/asm/uaccess.h
View File

@@ -12,30 +12,6 @@
#include <asm/smap.h>
#include <asm/extable.h>
/*
* The fs value determines whether argument validity checking should be
* performed or not. If get_fs() == USER_DS, checking is performed, with
* get_fs() == KERNEL_DS, checking is bypassed.
*
* For historical reasons, these macros are grossly misnamed.
*/
#define MAKE_MM_SEG(s) ((mm_segment_t) { (s) })
#define KERNEL_DS MAKE_MM_SEG(-1UL)
#define USER_DS MAKE_MM_SEG(TASK_SIZE_MAX)
#define get_fs() (current->thread.addr_limit)
static inline void set_fs(mm_segment_t fs)
{
current->thread.addr_limit = fs;
/* On user-mode return, check fs is correct */
set_thread_flag(TIF_FSCHECK);
}
#define uaccess_kernel() (get_fs().seg == KERNEL_DS.seg)
#define user_addr_max() (current->thread.addr_limit.seg)
/*
* Test whether a block of memory is a valid user space address.
* Returns 0 if the range is valid, nonzero otherwise.
@@ -93,7 +69,7 @@ static inline bool pagefault_disabled(void);
#define access_ok(addr, size) \
({ \
WARN_ON_IN_IRQ(); \
likely(!__range_not_ok(addr, size, user_addr_max())); \
likely(!__range_not_ok(addr, size, TASK_SIZE_MAX)); \
})
/*