[PATCH] Fix segfault on empty else

Andrew STUBBS
2006-06-20T14:34:03Z

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The attached patch fixes a segmentation fault that occurs when a GDB
script has an empty else clause.

E.g.

if $cond
echo here\n
else
# boom
end

The command structure is apparently read correctly (from the user's
perspective), but GDB will crash when it tries to a) execute the else
clause ($cond == 0), or b) free the command, if the command is not in a
define or the user-defined command is redefined.

This problem is caused by a pointer that is only initialised when it is
first used, which is never when there are no commands.

:ADDPATCH CLI:

Andrew Stubbs

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2006-06-20 Andrew Stubbs <andrew.stubbs@st.com>

* cli/cli-script.c (realloc_body_list): Zero new parts of body_list.

Index: src/gdb/cli/cli-script.c
===================================================================
--- src.orig/gdb/cli/cli-script.c 2006-04-07 14:31:15.000000000 +0100
+++ src/gdb/cli/cli-script.c 2006-06-20 15:15:25.000000000 +0100
@@ -701,6 +701,7 @@ realloc_body_list (struct command_line *
xmalloc (sizeof (struct command_line *) * new_length);

memcpy (body_list, command->body_list, sizeof (struct command_line *) * n);
+ memset (body_list + n, 0, sizeof (struct command_line *) * (new_length - n));

xfree (command->body_list);
command->body_list = body_list;