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[pushed] Fix uninitialized value access when very first GDB command entered is <RET>
- From: Pedro Alves <palves at redhat dot com>
- To: gdb-patches at sourceware dot org
- Date: Wed, 29 Oct 2014 15:01:40 +0000
- Subject: [pushed] Fix uninitialized value access when very first GDB command entered is <RET>
- Authentication-results: sourceware.org; auth=none
While running GDB under Valgrind, I noticed that if the very first
command entered is just <RET>, GDB accesses an uninitialized value:
$ valgrind ./gdb -q -nx
==26790== Memcheck, a memory error detector
==26790== Copyright (C) 2002-2013, and GNU GPL'd, by Julian Seward et al.
==26790== Using Valgrind-3.9.0 and LibVEX; rerun with -h for copyright info
==26790== Command: ./gdb -q -nx
==26790==
(gdb)
==26790== Conditional jump or move depends on uninitialised value(s)
==26790== at 0x619DFC: command_line_handler (event-top.c:588)
==26790== by 0x7813D5: rl_callback_read_char (callback.c:220)
==26790== by 0x6194B4: rl_callback_read_char_wrapper (event-top.c:166)
==26790== by 0x61988A: stdin_event_handler (event-top.c:372)
==26790== by 0x61847D: handle_file_event (event-loop.c:762)
==26790== by 0x617964: process_event (event-loop.c:339)
==26790== by 0x617A2B: gdb_do_one_event (event-loop.c:403)
==26790== by 0x617A7B: start_event_loop (event-loop.c:428)
==26790== by 0x6194E6: cli_command_loop (event-top.c:181)
==26790== by 0x60F86B: current_interp_command_loop (interps.c:317)
==26790== by 0x610A34: captured_command_loop (main.c:321)
==26790== by 0x60C728: catch_errors (exceptions.c:237)
==26790==
(gdb)
It's this check here:
/* If we just got an empty line, and that is supposed to repeat the
previous command, return the value in the global buffer. */
if (repeat && p == linebuffer && *p != '\\')
{
The problem is that linebuffer's contents were never initialized at
this point.
gdb/
2014-10-29 Pedro Alves <palves@redhat.com>
* event-top.c (command_line_handler): Clear the first byte of
linebuffer, when it is first allocated.
---
gdb/ChangeLog | 5 +++++
gdb/event-top.c | 1 +
2 files changed, 6 insertions(+)
diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index 1125b1e..58a7e98 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,5 +1,10 @@
2014-10-29 Pedro Alves <palves@redhat.com>
+ * event-top.c (command_line_handler): Clear the first byte of
+ linebuffer, when it is first allocated.
+
+2014-10-29 Pedro Alves <palves@redhat.com>
+
* tui/tui.c (tui_rl_switch_mode): Wrap tui_enable/tui_disable in
TRY_CATCH.
diff --git a/gdb/event-top.c b/gdb/event-top.c
index 3f9deec..f539733 100644
--- a/gdb/event-top.c
+++ b/gdb/event-top.c
@@ -467,6 +467,7 @@ command_line_handler (char *rl)
{
linelength = 80;
linebuffer = (char *) xmalloc (linelength);
+ linebuffer[0] = '\0';
}
p = linebuffer;
--
1.9.3