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From:   Andrey Konovalov <andreyknvl@google.com>
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Subject: [PATCH v6 06/11] arm64: untag user address in __do_user_fault
Date:   Thu, 30 Aug 2018 13:41:11 +0200
Message-Id: <b0f447bbf035a5b0a6cffa9035f1f922266a9f35.1535629099.git.andreyknvl@google.com>
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In __do_user_fault the fault address is being compared to TASK_SIZE to
find out whether the address lies in the kernel or in user space. Since
the fault address is coming from a user it can be tagged.

Untag the pointer before comparing.

Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
---
 arch/arm64/mm/fault.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c
index 50b30ff30de4..871fb3c38b23 100644
--- a/arch/arm64/mm/fault.c
+++ b/arch/arm64/mm/fault.c
@@ -313,7 +313,7 @@ static void __do_user_fault(struct siginfo *info, unsigned int esr)
 	 * type", so we ignore this wrinkle and just return the translation
 	 * fault.)
 	 */
-	if (current->thread.fault_address >= TASK_SIZE) {
+	if (untagged_addr(current->thread.fault_address) >= TASK_SIZE) {
 		switch (ESR_ELx_EC(esr)) {
 		case ESR_ELx_EC_DABT_LOW:
 			/*
-- 
2.19.0.rc0.228.g281dcd1b4d0-goog