arm64: mm: don't print out page table entries on EL0 faults

kristina-martsenko · wildea01 · commit bf396c09c244 · 2017-06-12T12:33:37.000+01:00
When we take a fault from EL0 that can't be handled, we print out the
page table entries associated with the faulting address. This allows
userspace to print out any current page table entries, including kernel
(TTBR1) entries. Exposing kernel mappings like this could pose a
security risk, so don't print out page table information on EL0 faults.
(But still print it out for EL1 faults.) This also follows the same
behaviour as x86, printing out page table entries on kernel mode faults
but not user mode faults.

Acked-by: Mark Rutland &lt;mark.rutland@arm.com&gt;
Signed-off-by: Kristina Martsenko &lt;kristina.martsenko@arm.com&gt;
Signed-off-by: Will Deacon &lt;will.deacon@arm.com&gt;
diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c
@@ -264,7 +264,6 @@ static void __do_user_fault(struct task_struct *tsk, unsigned long addr,
 		pr_info("%s[%d]: unhandled %s (%d) at 0x%08lx, esr 0x%03x\n",
 			tsk->comm, task_pid_nr(tsk), inf->name, sig,
 			addr, esr);
-		show_pte(addr);
 		__show_regs(regs);
 	}
 

Original file line number	Diff line number	Diff line change
`@@ -264,7 +264,6 @@ static void __do_user_fault(struct task_struct *tsk, unsigned long addr,`
`264`	`264`	`pr_info("%s[%d]: unhandled %s (%d) at 0x%08lx, esr 0x%03x\n",`
`265`	`265`	`tsk->comm, task_pid_nr(tsk), inf->name, sig,`
`266`	`266`	`addr, esr);`
`267`		`- show_pte(addr);`
`268`	`267`	`__show_regs(regs);`
`269`	`268`	`}`
`270`	`269`