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[RFA] Fix inline frame crash in handle_inferior_event
- From: "Maciej W. Rozycki" <macro at codesourcery dot com>
- To: <gdb-patches at sourceware dot org>
- Date: Wed, 13 Jun 2012 06:12:54 +0100
- Subject: [RFA] Fix inline frame crash in handle_inferior_event
Hi,
Jan's recent change to enable mcheck has triggered a segfault in
gdb.opt/inline-cmds.exp on mips-sde-elf and mips-linux-gnu targets (any
multilibs). I have tracked the problem down to dereferencing a pointer to
a frame structure that has been already freed. The cause is in
handle_inferior_event, where skip_inline_frames is called and that may
invalidate the frame cache. That doesn't stop handle_inferior_event
though from trying to use a stale pointer to the current frame structure
in the next step. This path is only used for targets that have delay
slots (gdbarch_single_step_through_delay_p is true; that applies to CRIS
and MIPS targets only), which I infer is why it wasn't caught straight
away. This must be a long-standing bug.
The change below works for me, the gdbarch_single_step_through_delay_p
check that guards the problematic pointer dereference uses gdbarch
determined by the invalidated frame too, so I've decided to reinit both
frame and gdbarch unconditionally.
No regressions in mips-sde-elf, mips-linux-gnu or i686-linux-gnu targets.
OK to apply?
2012-06-13 Maciej W. Rozycki <macro@codesourcery.com>
gdb/
* infrun.c (handle_inferior_event): Re-fetch frame and gdbarch
after hiding inline functions.
Maciej
gdb-wait-inline-frames.diff
Index: gdb-fsf-trunk-quilt/gdb/infrun.c
===================================================================
--- gdb-fsf-trunk-quilt.orig/gdb/infrun.c 2012-06-08 23:45:43.000000000 +0100
+++ gdb-fsf-trunk-quilt/gdb/infrun.c 2012-06-12 08:29:31.063547656 +0100
@@ -4084,7 +4084,13 @@ handle_inferior_event (struct execution_
&& pc_at_non_inline_function (aspace,
ecs->event_thread->prev_pc,
&ecs->ws)))
- skip_inline_frames (ecs->ptid);
+ {
+ skip_inline_frames (ecs->ptid);
+ /* Re-fetch current thread's frame in case that invalidated
+ the frame cache. */
+ frame = get_current_frame ();
+ gdbarch = get_frame_arch (frame);
+ }
}
if (ecs->event_thread->suspend.stop_signal == GDB_SIGNAL_TRAP