[PATCH v4 18/26] arm64: vdso32: Replace TASK_SIZE_32 check in vgettimeofday

[Vincenzo Frascino <vincenzo.frascino@arm.com>]

For ABI compatibility with arm32, the compat vDSO layer on arm64 needs
to return -EINVAL when UINTPTR_MAX is passed as argument to the
clock_get* functions.

Replace TASK_SIZE_32 with a more semantically correct formula that checks
for wrapping around 0.

Note: This will allow to not define TASK_SIZE_32 for the vdso headers in a
future patch that will introduce asm/vdso/processor.h on arm64.

Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
---
 arch/arm64/kernel/vdso32/vgettimeofday.c | 12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)

diff --git a/arch/arm64/kernel/vdso32/vgettimeofday.c b/arch/arm64/kernel/vdso32/vgettimeofday.c
index 54fc1c2ce93f..91138077b073 100644
--- a/arch/arm64/kernel/vdso32/vgettimeofday.c
+++ b/arch/arm64/kernel/vdso32/vgettimeofday.c
@@ -8,11 +8,14 @@
 #include <linux/time.h>
 #include <linux/types.h>
 
+#define VALID_CLOCK_ID(x) \
+	((x >= 0) && (x < VDSO_BASES))
+
 int __vdso_clock_gettime(clockid_t clock,
 			 struct old_timespec32 *ts)
 {
 	/* The checks below are required for ABI consistency with arm */
-	if ((u32)ts >= TASK_SIZE_32)
+	if ((u32)ts > UINTPTR_MAX - sizeof(*ts) + 1)
 		return -EFAULT;
 
 	return __cvdso_clock_gettime32(clock, ts);
@@ -22,7 +25,7 @@ int __vdso_clock_gettime64(clockid_t clock,
 			   struct __kernel_timespec *ts)
 {
 	/* The checks below are required for ABI consistency with arm */
-	if ((u32)ts >= TASK_SIZE_32)
+	if ((u32)ts > UINTPTR_MAX - sizeof(*ts) + 1)
 		return -EFAULT;
 
 	return __cvdso_clock_gettime(clock, ts);
@@ -38,9 +41,12 @@ int __vdso_clock_getres(clockid_t clock_id,
 			struct old_timespec32 *res)
 {
 	/* The checks below are required for ABI consistency with arm */
-	if ((u32)res >= TASK_SIZE_32)
+	if ((u32)res > UINTPTR_MAX - sizeof(res) + 1)
 		return -EFAULT;
 
+	if (!VALID_CLOCK_ID(clock_id) && res == NULL)
+		return -EINVAL;
+
 	return __cvdso_clock_getres_time32(clock_id, res);
 }
 
-- 
2.25.1