[PATCH v2 05/18] x86: remove __range_not_ok()

Arnd Bergmann
2022-02-16T13:16:49Z

From: Arnd Bergmann <arnd@arndb.de>

The __range_not_ok() helper is an x86 (and sparc64) specific interface
that does roughly the same thing as __access_ok(), but with different
calling conventions.

Change this to use the normal interface in order for consistency as we
clean up all access_ok() implementations.

This changes the limit from TASK_SIZE to TASK_SIZE_MAX, which Al points
out is the right thing do do here anyway.

The callers have to use __access_ok() instead of the normal access_ok()
though, because on x86 that contains a WARN_ON_IN_IRQ() check that cannot
be used inside of NMI context while tracing.

Suggested-by: Al Viro <viro@zeniv.linux.org.uk>
Suggested-by: Christoph Hellwig <hch@infradead.org>
Link: https://lore.kernel.org/lkml/YgsUKcXGR7r4nINj@zeniv-ca.linux.org.uk/
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
arch/x86/events/core.c | 2 +-
arch/x86/include/asm/uaccess.h | 10 ++++++----
arch/x86/kernel/dumpstack.c | 2 +-
arch/x86/kernel/stacktrace.c | 2 +-
arch/x86/lib/usercopy.c | 2 +-
5 files changed, 10 insertions(+), 8 deletions(-)

diff --git a/arch/x86/events/core.c b/arch/x86/events/core.c
index e686c5e0537b..eef816fc216d 100644
--- a/arch/x86/events/core.c
+++ b/arch/x86/events/core.c
@@ -2794,7 +2794,7 @@ perf_callchain_kernel(struct perf_callchain_entry_ctx *entry, struct pt_regs *re
static inline int
valid_user_frame(const void __user *fp, unsigned long size)
{
- return (__range_not_ok(fp, size, TASK_SIZE) == 0);
+ return __access_ok(fp, size);
}

static unsigned long get_segment_base(unsigned int segment)
diff --git a/arch/x86/include/asm/uaccess.h b/arch/x86/include/asm/uaccess.h
index ac96f9b2d64b..79c4869ccdd6 100644
--- a/arch/x86/include/asm/uaccess.h
+++ b/arch/x86/include/asm/uaccess.h
@@ -16,8 +16,10 @@
* 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, unsigned long limit)
+static inline bool __chk_range_not_ok(unsigned long addr, unsigned long size)
{
+ unsigned long limit = TASK_SIZE_MAX;
+
/*
* If we have used "sizeof()" for the size,
* we know it won't overflow the limit (but
@@ -35,10 +37,10 @@ static inline bool __chk_range_not_ok(unsigned long addr, unsigned long size, un
return unlikely(addr > limit);
}

-#define __range_not_ok(addr, size, limit) \
+#define __access_ok(addr, size) \
({ \
__chk_user_ptr(addr); \
- __chk_range_not_ok((unsigned long __force)(addr), size, limit); \
+ !__chk_range_not_ok((unsigned long __force)(addr), size); \
})

#ifdef CONFIG_DEBUG_ATOMIC_SLEEP
@@ -69,7 +71,7 @@ static inline bool pagefault_disabled(void);
#define access_ok(addr, size) \
({ \
WARN_ON_IN_IRQ(); \
- likely(!__range_not_ok(addr, size, TASK_SIZE_MAX)); \
+ likely(__access_ok(addr, size)); \
})

extern int __get_user_1(void);
diff --git a/arch/x86/kernel/dumpstack.c b/arch/x86/kernel/dumpstack.c
index 53de044e5654..da534fb7b5c6 100644
--- a/arch/x86/kernel/dumpstack.c
+++ b/arch/x86/kernel/dumpstack.c
@@ -85,7 +85,7 @@ static int copy_code(struct pt_regs *regs, u8 *buf, unsigned long src,
* Make sure userspace isn't trying to trick us into dumping kernel
* memory by pointing the userspace instruction pointer at it.
*/
- if (__chk_range_not_ok(src, nbytes, TASK_SIZE_MAX))
+ if (!__access_ok((void __user *)src, nbytes))
return -EINVAL;

/*
diff --git a/arch/x86/kernel/stacktrace.c b/arch/x86/kernel/stacktrace.c
index 15b058eefc4e..ee117fcf46ed 100644
--- a/arch/x86/kernel/stacktrace.c
+++ b/arch/x86/kernel/stacktrace.c
@@ -90,7 +90,7 @@ copy_stack_frame(const struct stack_frame_user __user *fp,
{
int ret;

- if (__range_not_ok(fp, sizeof(*frame), TASK_SIZE))
+ if (!__access_ok(fp, sizeof(*frame)))
return 0;

ret = 1;
diff --git a/arch/x86/lib/usercopy.c b/arch/x86/lib/usercopy.c
index c3e8a62ca561..ad0139d25401 100644
--- a/arch/x86/lib/usercopy.c
+++ b/arch/x86/lib/usercopy.c
@@ -32,7 +32,7 @@ copy_from_user_nmi(void *to, const void __user *from, unsigned long n)
{
unsigned long ret;

- if (__range_not_ok(from, n, TASK_SIZE))
+ if (!__access_ok(from, n))
return n;

if (!nmi_uaccess_okay())
--
2.29.2