From: Arnd Bergmann <arnd@xxxxxxxx>
The way that access_ok() is defined on x86 is slightly different from
most other architectures, and a bit more complex.
The generic version tends to result in the best output on all
architectures, as it results in single comparison against a constant
limit for calls with a known size.
There are a few callers of __range_not_ok(), all of which use TASK_SIZE
as the limit rather than TASK_SIZE_MAX, but I could not see any reason
for picking this. Changing these to call __access_ok() instead uses the
default limit, but keeps the behavior otherwise.
x86 is the only architecture with a WARN_ON_IN_IRQ() checking
access_ok(), but it's probably best to leave that in place.
Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx>
---
arch/x86/include/asm/uaccess.h | 25 +++----------------------
1 file changed, 3 insertions(+), 22 deletions(-)
diff --git a/arch/x86/include/asm/uaccess.h b/arch/x86/include/asm/uaccess.h
index 79c4869ccdd6..a59ba2578e64 100644
--- a/arch/x86/include/asm/uaccess.h
+++ b/arch/x86/include/asm/uaccess.h
@@ -16,33 +16,14 @@
* Test whether a block of memory is a valid user space address.
* Returns 0 if the range is valid, nonzero otherwise.
*/
-static inline bool __chk_range_not_ok(unsigned long addr, unsigned long size)
+static inline bool __access_ok(void __user *ptr, unsigned long size)
{
unsigned long limit = TASK_SIZE_MAX;
+ unsigned long addr = ptr;
- /*
- * If we have used "sizeof()" for the size,
- * we know it won't overflow the limit (but
- * it might overflow the 'addr', so it's
- * important to subtract the size from the
- * limit, not add it to the address).
- */
- if (__builtin_constant_p(size))
- return unlikely(addr > limit - size);
-
- /* Arbitrary sizes? Be careful about overflow */
- addr += size;
- if (unlikely(addr < size))
- return true;
- return unlikely(addr > limit);
+ return (size <= limit) && (addr <= (limit - size));
}
-#define __access_ok(addr, size) \
-({ \
- __chk_user_ptr(addr); \
- !__chk_range_not_ok((unsigned long __force)(addr), size); \
-})
-
#ifdef CONFIG_DEBUG_ATOMIC_SLEEP
static inline bool pagefault_disabled(void);
# define WARN_ON_IN_IRQ() \
--
2.29.2
