Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 0cb15571 authored by Josh Poimboeuf's avatar Josh Poimboeuf Committed by Greg Kroah-Hartman
Browse files

x86/unwind/orc: Fix error handling in __unwind_start() 



commit 71c95825289f585014fe9741b051d32a7a916680 upstream.

The unwind_state 'error' field is used to inform the reliable unwinding
code that the stack trace can't be trusted.  Set this field for all
errors in __unwind_start().

Also, move the zeroing out of the unwind_state struct to before the ORC
table initialization check, to prevent the caller from reading
uninitialized data if the ORC table is corrupted.

Fixes: af085d90 ("stacktrace/x86: add function for detecting reliable stack traces")
Fixes: d3a09104 ("x86/unwinder/orc: Dont bail on stack overflow")
Fixes: 98d0c8ebf77e ("x86/unwind/orc: Prevent unwinding before ORC initialization")
Reported-by: default avatarPavel Machek <pavel@denx.de>
Signed-off-by: default avatarJosh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/d6ac7215a84ca92b895fdd2e1aa546729417e6e6.1589487277.git.jpoimboe@redhat.com


Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent e550fa72

arch/x86/kernel/unwind_orc.c

+9 −7
Original line number Diff line number Diff line
@@ -505,23 +505,23 @@ EXPORT_SYMBOL_GPL(unwind_next_frame); 
void __unwind_start(struct unwind_state *state, struct task_struct *task,

		    struct pt_regs *regs, unsigned long *first_frame)

{

	if (!orc_init)

		goto done;



	memset(state, 0, sizeof(*state));

	state->task = task;



	if (!orc_init)

		goto err;



	/*

	 * Refuse to unwind the stack of a task while it's executing on another

	 * CPU.  This check is racy, but that's ok: the unwinder has other

	 * checks to prevent it from going off the rails.

	 */

	if (task_on_another_cpu(task))

		goto done;

		goto err;



	if (regs) {

		if (user_mode(regs))

			goto done;

			goto the_end;



		state->ip = regs->ip;

		state->sp = kernel_stack_pointer(regs);
@@ -554,6 +554,7 @@ void __unwind_start(struct unwind_state *state, struct task_struct *task, 
		 * generate some kind of backtrace if this happens.

		 */

		void *next_page = (void *)PAGE_ALIGN((unsigned long)state->sp);

		state->error = true;

		if (get_stack_info(next_page, state->task, &state->stack_info,

				   &state->stack_mask))

			return;
@@ -579,8 +580,9 @@ void __unwind_start(struct unwind_state *state, struct task_struct *task, 


	return;



done:

err:

	state->error = true;

the_end:

	state->stack_info.type = STACK_TYPE_UNKNOWN;

	return;

}

EXPORT_SYMBOL_GPL(__unwind_start);