btrace, frame: fix crash in get_frame_type
authorMarkus Metzger <markus.t.metzger@intel.com>
Tue, 26 Jan 2016 13:58:44 +0000 (14:58 +0100)
committerMarkus Metzger <markus.t.metzger@intel.com>
Fri, 12 Feb 2016 08:49:48 +0000 (09:49 +0100)
commit33b4777ca1b7b456af8201b98eda27d1b272cbab
treeed42f9fc456aba8951c1abcb4ecf050b434caaab
parenta038fa3e14a477d4d72a26c2e139fa47d2774be2
btrace, frame: fix crash in get_frame_type

In skip_artificial_frames we repeatedly call get_prev_frame_always until we get
a non-inline and non-tailcall frame assuming that there must be such a frame
eventually.

For record targets, however, we may have a frame chain that consists only of
artificial frames.  This leads to a crash in get_frame_type when dereferencing a
NULL frame pointer.

Change skip_artificial_frames and skip_tailcall_frames to return NULL in such a
case and modify each caller to cope with a NULL return.

In frame_unwind_caller_pc and frame_unwind_caller_arch, we simply assert that
the returned value is not NULL.  Their caller was supposed to check
frame_unwind_caller_id before calling those functions.

In other cases, we thrown an error.

In infcmd further move the skip_tailcall_frames call to the forward-stepping
case since we don't need a frame for reverse execution and we don't want to fail
because of that.  Reverse-finish does make sense for a tailcall frame.

gdb/
* frame.h (skip_tailcall_frames): Update comment.
* frame.c (skip_artificial_frames, skip_tailcall_frames): Return NULL
if only artificial frames are found.  Update comment.
(frame_unwind_caller_id): Handle NULL return.
(frame_unwind_caller_pc, frame_unwind_caller_arch): Assert that
skip_artificial_frames does not return NULL.
(frame_pop): Add an error if only tailcall frames are found.
* infcmd.c (finish_command): Move skip_tailcall_frames call into forward-
execution case.  Add an error if only tailcall frames are found.

testsuite/
* gdb.btrace/tailcall-only.exp: New.
* gdb.btrace/tailcall-only.c: New.
* gdb.btrace/x86_64-tailcall-only.S: New.
* gdb.btrace/i686-tailcall-only.S: New.
gdb/ChangeLog
gdb/frame.c
gdb/frame.h
gdb/infcmd.c
gdb/testsuite/ChangeLog
gdb/testsuite/gdb.btrace/i686-tailcall-only.S [new file with mode: 0644]
gdb/testsuite/gdb.btrace/tailcall-only.c [new file with mode: 0644]
gdb/testsuite/gdb.btrace/tailcall-only.exp [new file with mode: 0644]
gdb/testsuite/gdb.btrace/x86_64-tailcall-only.S [new file with mode: 0644]