arm64: stacktrace: Check kretprobe_find_ret_addr() return value

If kretprobe_find_ret_addr() fails to find the original return address,
it returns 0. Check for this case so that a reliable stacktrace won't
silently ignore it.

Signed-off-by: Mark Rutland <[email protected]>
Cc: Andrea della Porta <[email protected]>
Cc: Breno Leitao <[email protected]>
Cc: Josh Poimboeuf <[email protected]>
Cc: Miroslav Benes <[email protected]>
Cc: Petr Mladek <[email protected]>
Cc: Song Liu <[email protected]>
Cc: Will Deacon <[email protected]>
Reviewed-and-tested-by: Song Liu <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Catalin Marinas <[email protected]>

Author: mrutland-arm

arch/arm64/kernel/stacktrace.c

@@ -152,6 +152,8 @@ kunwind_recover_return_address(struct kunwind_state *state)
 		orig_pc = kretprobe_find_ret_addr(state->task,
 						  (void *)state->common.fp,
 						  &state->kr_cur);
+		if (!orig_pc)
+			return -EINVAL;
 		state->common.pc = orig_pc;
 		state->flags.kretprobe = 1;
 	}