[PATCH v5 01/12] Zero-initialize linux note sections

Pedro Franco de Carvalho
2018-10-22T22:33:47Z

This patches changes linux-tdep.c so that the buffer used to write
note sections when generating a core file is zero-initialized. This
way, bytes that are not collected won't contain random
data (e.g. padding bytes).

gdb/ChangeLog:
YYYY-MM-DD Pedro Franco de Carvalho <pedromfc@linux.ibm.com>

* linux-tdep.c (linux_collect_regset_section_cb): Use
std::vector<gdb_byte> instead of char * and malloc for buf.
Remove xfree.
---
gdb/linux-tdep.c | 14 ++++++++------
1 file changed, 8 insertions(+), 6 deletions(-)

diff --git a/gdb/linux-tdep.c b/gdb/linux-tdep.c
index 352114943f..c958c0dfe9 100644
--- a/gdb/linux-tdep.c
+++ b/gdb/linux-tdep.c
@@ -1584,7 +1584,6 @@ linux_collect_regset_section_cb (const char *sect_name, int supply_size,
int collect_size, const struct regset *regset,
const char *human_name, void *cb_data)
{
- char *buf;
struct linux_collect_regset_section_cb_data *data
= (struct linux_collect_regset_section_cb_data *) cb_data;
bool variable_size_section = (regset != NULL
@@ -1598,19 +1597,22 @@ linux_collect_regset_section_cb (const char *sect_name, int supply_size,

gdb_assert (regset && regset->collect_regset);

- buf = (char *) xmalloc (collect_size);
- regset->collect_regset (regset, data->regcache, -1, buf, collect_size);
+ /* This is intentionally zero-initialized by using std::vector, so
+ that any padding bytes in the core file will show as 0. */
+ std::vector<gdb_byte> buf (collect_size);
+
+ regset->collect_regset (regset, data->regcache, -1, buf.data (),
+ collect_size);

/* PRSTATUS still needs to be treated specially. */
if (strcmp (sect_name, ".reg") == 0)
data->note_data = (char *) elfcore_write_prstatus
(data->obfd, data->note_data, data->note_size, data->lwp,
- gdb_signal_to_host (data->stop_signal), buf);
+ gdb_signal_to_host (data->stop_signal), buf.data ());
else
data->note_data = (char *) elfcore_write_register_note
(data->obfd, data->note_data, data->note_size,
- sect_name, buf, collect_size);
- xfree (buf);
+ sect_name, buf.data (), collect_size);

if (data->note_data == NULL)
data->abort_iteration = 1;
--
2.13.6