Commit 1f65c13e authored Sep 24, 2013 by AKASHI Takahiro Committed by Catalin Marinas Sep 25, 2013

arm64: avoid multiple evaluation of ptr in get_user/put_user()



get_user() is defined as a function macro in arm64, and trace_get_user()
calls it as followed:
     get_user(ch, ptr++);
Since the second parameter occurs twice in the definition, 'ptr++' is
unexpectedly evaluated twice and trace_get_user() will generate a bogus
string from user-provided one. As a result, some ftrace sysfs operations,
like "echo FUNCNAME > set_ftrace_filter," hit this case and eventually fail.
This patch fixes the issue both in get_user() and put_user().

Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>
[catalin.marinas@arm.com: added __user type annotation and s/optr/__p/]
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

parent 25804e6a

arch/arm64/include/asm/uaccess.h

+6 −4

Original line number	Diff line number	Diff line
		@@ -166,9 +166,10 @@ do { \

		#define get_user(x, ptr) \
		({ \
		__typeof__((ptr)) __user __p = (ptr); \
		might_fault(); \
		access_ok(VERIFY_READ, (ptr), sizeof(*(ptr))) ? \
		__get_user((x), (ptr)) : \
		access_ok(VERIFY_READ, __p, sizeof(*__p)) ? \
		__get_user((x), __p) : \
		((x) = 0, -EFAULT); \
		})

		@@ -227,9 +228,10 @@ do { \

		#define put_user(x, ptr) \
		({ \
		__typeof__((ptr)) __user __p = (ptr); \
		might_fault(); \
		access_ok(VERIFY_WRITE, (ptr), sizeof(*(ptr))) ? \
		__put_user((x), (ptr)) : \
		access_ok(VERIFY_WRITE, __p, sizeof(*__p)) ? \
		__put_user((x), __p) : \
		-EFAULT; \
		})