[PATCH 2/4] x86: Fix the hw_breakpoint range check

[Frederic Weisbecker <fweisbec@gmail.com>]

From: Oleg Nesterov <oleg@redhat.com>

arch_check_bp_in_kernelspace() tries to avoid the overflow and does 2
TASK_SIZE checks but it needs OR, not AND. Consider va = TASK_SIZE -1
and len = 2 case.

Note: TASK_SIZE doesn't look right at least on x86, I think it should
be replaced by TASK_SIZE_MAX.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Fixes: 0067f1297241ea567f2b22a455519752d70fcca9
Cc: <stable@vger.kernel.org>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
---
 arch/x86/kernel/hw_breakpoint.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/kernel/hw_breakpoint.c b/arch/x86/kernel/hw_breakpoint.c
index f66ff16..1131c1f 100644
--- a/arch/x86/kernel/hw_breakpoint.c
+++ b/arch/x86/kernel/hw_breakpoint.c
@@ -200,7 +200,7 @@ int arch_check_bp_in_kernelspace(struct perf_event *bp)
 	va = info->address;
 	len = get_hbp_len(info->len);
 
-	return (va >= TASK_SIZE) && ((va + len - 1) >= TASK_SIZE);
+	return (va >= TASK_SIZE) || ((va + len - 1) >= TASK_SIZE);
 }
 
 int arch_bp_generic_fields(int x86_len, int x86_type,
-- 
1.8.3.1