From 3aafd2ffb61b3afaba478449ec0dbe45f38dac40 Mon Sep 17 00:00:00 2001 From: Pedro Alves Date: Mon, 2 Sep 2013 15:15:57 +0000 Subject: [PATCH] [gdbserver] Fix trace-buffer-size.exp FAILs. I'm seeing trace-buffer-size.exp failing (with gdbserver): (gdb) PASS: gdb.trace/trace-buffer-size.exp: tstatus check 2 show trace-buffer-size 4 Requested size of trace buffer is 4. (gdb) PASS: gdb.trace/trace-buffer-size.exp: show trace buffer size set trace-buffer-size -1 memory clobbered past end of allocated block Remote connection closed (gdb) FAIL: gdb.trace/trace-buffer-size.exp: set trace buffer size 2 set trace-buffer-size unlimited (gdb) PASS: gdb.trace/trace-buffer-size.exp: set trace-buffer-size unlimited That "memory clobbered past end of allocated block" is mcheck triggering. Valgrind shows: ==23624== Invalid write of size 1 ==23624== at 0x418DD8: clear_trace_buffer (tracepoint.c:1443) ==23624== by 0x418F3A: init_trace_buffer (tracepoint.c:1497) ==23624== by 0x41D95B: cmd_bigqtbuffer_size (tracepoint.c:4061) ==23624== by 0x41DEEC: handle_tracepoint_general_set (tracepoint.c:4193) clear_trace_buffer does: static void clear_trace_buffer (void) { trace_buffer_start = trace_buffer_lo; trace_buffer_free = trace_buffer_lo; trace_buffer_end_free = trace_buffer_hi; trace_buffer_wrap = trace_buffer_hi; /* A traceframe with zeroed fields marks the end of trace data. */ ((struct traceframe *) trace_buffer_free)->tpnum = 0; ((struct traceframe *) trace_buffer_free)->data_size = 0; traceframe_read_count = traceframe_write_count = 0; traceframes_created = 0; } And the tpnum+data_size fields are over 4 bytes... This fixes it by ensuring we allocate space at least for an EOB. We have code elsewhere that relies on the EOB being present (like e.g., find_traceframe), so this seems simplest. gdb/gdbserver/ 2013-09-02 Pedro Alves * tracepoint.c (TRACEFRAME_EOB_MARKER_SIZE): New macro. (init_trace_buffer): Ensure at least TRACEFRAME_EOB_MARKER_SIZE is allocated. (trace_buffer_alloc): Use TRACEFRAME_EOB_MARKER_SIZE. --- gdb/gdbserver/ChangeLog | 7 +++++++ gdb/gdbserver/tracepoint.c | 17 +++++++++++++---- 2 files changed, 20 insertions(+), 4 deletions(-) diff --git a/gdb/gdbserver/ChangeLog b/gdb/gdbserver/ChangeLog index 54348e5a732..f0651aa0a95 100644 --- a/gdb/gdbserver/ChangeLog +++ b/gdb/gdbserver/ChangeLog @@ -1,3 +1,10 @@ +2013-09-02 Pedro Alves + + * tracepoint.c (TRACEFRAME_EOB_MARKER_SIZE): New macro. + (init_trace_buffer): Ensure at least TRACEFRAME_EOB_MARKER_SIZE is + allocated. + (trace_buffer_alloc): Use TRACEFRAME_EOB_MARKER_SIZE. + 2013-09-02 Pierre Muller * win32-low.c (child_xfer_memory): Check if ReadProcessMemory diff --git a/gdb/gdbserver/tracepoint.c b/gdb/gdbserver/tracepoint.c index 5c0dec7f6b4..1327845657d 100644 --- a/gdb/gdbserver/tracepoint.c +++ b/gdb/gdbserver/tracepoint.c @@ -982,6 +982,10 @@ struct traceframe } ATTR_PACKED; +/* The size of the EOB marker, in bytes. A traceframe with zeroed + fields (and no data) marks the end of trace data. */ +#define TRACEFRAME_EOB_MARKER_SIZE offsetof (struct traceframe, data) + /* The traceframe to be used as the source of data to send back to GDB. A value of -1 means to get data from the live program. */ @@ -1487,12 +1491,17 @@ clear_inferior_trace_buffer (void) static void init_trace_buffer (LONGEST bufsize) { + size_t alloc_size; + trace_buffer_size = bufsize; - /* If we already have a trace buffer, try realloc'ing. */ - trace_buffer_lo = xrealloc (trace_buffer_lo, bufsize); + /* Make sure to internally allocate at least space for the EOB + marker. */ + alloc_size = (bufsize < TRACEFRAME_EOB_MARKER_SIZE + ? TRACEFRAME_EOB_MARKER_SIZE : bufsize); + trace_buffer_lo = xrealloc (trace_buffer_lo, alloc_size); - trace_buffer_hi = trace_buffer_lo + bufsize; + trace_buffer_hi = trace_buffer_lo + trace_buffer_size; clear_trace_buffer (); } @@ -1532,7 +1541,7 @@ trace_buffer_alloc (size_t amt) (long) amt, (long) sizeof (struct traceframe)); /* Account for the EOB marker. */ - amt += sizeof (struct traceframe); + amt += TRACEFRAME_EOB_MARKER_SIZE; #ifdef IN_PROCESS_AGENT again: -- 2.30.2