arm64: kernel: Save and restore UAO and addr_limit on exception entry
If we take an exception while at EL1, the exception handler inherits
the original context's addr_limit and PSTATE.UAO values. To be consistent
always reset addr_limit and PSTATE.UAO on (re-)entry to EL1. This
prevents accidental re-use of the original context's addr_limit.
Based on a similar patch for arm from Russell King.
Cc: <stable@vger.kernel.org> # 4.6-
Acked-by: Will Deacon <will.deacon@arm.com>
Reviewed-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: James Morse <james.morse@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c
index 013e2cb..b1166d1 100644
--- a/arch/arm64/mm/fault.c
+++ b/arch/arm64/mm/fault.c
@@ -280,7 +280,8 @@
}
if (permission_fault(esr) && (addr < USER_DS)) {
- if (get_fs() == KERNEL_DS)
+ /* regs->orig_addr_limit may be 0 if we entered from EL0 */
+ if (regs->orig_addr_limit == KERNEL_DS)
die("Accessing user space memory with fs=KERNEL_DS", regs, esr);
if (!search_exception_tables(regs->pc))