From 938f0e2f6766e90a5ddc5df00e97a68873fd1252 Mon Sep 17 00:00:00 2001 From: Andrew Burgess Date: Wed, 2 Apr 2014 17:02:51 +0100 Subject: Remove previous frame if an error occurs when computing frame id during unwind. https://sourceware.org/ml/gdb-patches/2014-05/msg00712.html If an error is thrown during computing a frame id then the frame is left in existence but without a valid frame id, this will trigger internal errors if/when the frame is later visited (for example in a backtrace). This patch catches errors raised while computing the frame id, and arranges for the new frame, the one without a frame id, to be removed from the linked list of frames. gdb/ChangeLog: * frame.c (remove_prev_frame): New function. (get_prev_frame_if_no_cycle): Create / discard cleanup using remove_prev_frame. gdb/testsuite/ChangeLog: * gdb.arch/amd64-invalid-stack-middle.S: New file. * gdb.arch/amd64-invalid-stack-middle.c: New file. * gdb.arch/amd64-invalid-stack-middle.exp: New file. * gdb.arch/amd64-invalid-stack-top.c: New file. * gdb.arch/amd64-invalid-stack-top.exp: New file. --- gdb/frame.c | 52 ++++++++++++++++++++++++++++++++++++++-------------- 1 file changed, 38 insertions(+), 14 deletions(-) (limited to 'gdb/frame.c') diff --git a/gdb/frame.c b/gdb/frame.c index 013d602..cbff25f 100644 --- a/gdb/frame.c +++ b/gdb/frame.c @@ -1738,6 +1738,22 @@ frame_register_unwind_location (struct frame_info *this_frame, int regnum, } } +/* Called during frame unwinding to remove a previous frame pointer from a + frame passed in ARG. */ + +static void +remove_prev_frame (void *arg) +{ + struct frame_info *this_frame, *prev_frame; + + this_frame = (struct frame_info *) arg; + prev_frame = this_frame->prev; + gdb_assert (prev_frame != NULL); + + prev_frame->next = NULL; + this_frame->prev = NULL; +} + /* Get the previous raw frame, and check that it is not identical to same other frame frame already in the chain. If it is, there is most likely a stack cycle, so we discard it, and mark THIS_FRAME as @@ -1750,28 +1766,36 @@ static struct frame_info * get_prev_frame_if_no_cycle (struct frame_info *this_frame) { struct frame_info *prev_frame; + struct cleanup *prev_frame_cleanup; prev_frame = get_prev_frame_raw (this_frame); if (prev_frame == NULL) return NULL; - compute_frame_id (prev_frame); - if (frame_stash_add (prev_frame)) - return prev_frame; + /* The cleanup will remove the previous frame that get_prev_frame_raw + linked onto THIS_FRAME. */ + prev_frame_cleanup = make_cleanup (remove_prev_frame, this_frame); - /* Another frame with the same id was already in the stash. We just - detected a cycle. */ - if (frame_debug) + compute_frame_id (prev_frame); + if (!frame_stash_add (prev_frame)) { - fprintf_unfiltered (gdb_stdlog, "-> "); - fprint_frame (gdb_stdlog, NULL); - fprintf_unfiltered (gdb_stdlog, " // this frame has same ID }\n"); + /* Another frame with the same id was already in the stash. We just + detected a cycle. */ + if (frame_debug) + { + fprintf_unfiltered (gdb_stdlog, "-> "); + fprint_frame (gdb_stdlog, NULL); + fprintf_unfiltered (gdb_stdlog, " // this frame has same ID }\n"); + } + this_frame->stop_reason = UNWIND_SAME_ID; + /* Unlink. */ + prev_frame->next = NULL; + this_frame->prev = NULL; + prev_frame = NULL; } - this_frame->stop_reason = UNWIND_SAME_ID; - /* Unlink. */ - prev_frame->next = NULL; - this_frame->prev = NULL; - return NULL; + + discard_cleanups (prev_frame_cleanup); + return prev_frame; } /* Return a "struct frame_info" corresponding to the frame that called -- cgit v1.1