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Fix Python unwinder frames regression

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The gdb.python/py-unwind.exp test is crashing GDB / leaving core dumps
in the test dir, even though it all passes cleanly.  The crash is not
visible in gdb.sum/gdb.log because it happens as side effect of the
"quit" command, while flushing the frame cache.

The problem is simply a typo in a 'for' loop's condition, introduced
by a recent change [4fa847d78e ("Remove MAX_REGISTER_SIZE from
py-unwind.c")], resulting in infinite loop / double-free.

The new test exposes the crash, like:

 Running src/gdb/testsuite/gdb.python/py-unwind.exp ...
 ERROR: Process no longer exists

gdb/ChangeLog:
2017-07-06  Pedro Alves  <palves@redhat.com>

	* python/py-unwind.c (pyuw_dealloc_cache): Fix for loop condition.

gdb/testsuite/ChangeLog:
2017-07-06  Pedro Alves  <palves@redhat.com>

	* gdb.python/py-unwind.exp: Test flushregs.
This commit is contained in:
Pedro Alves 2017-07-06 00:19:24 +01:00
parent 1d827a720c
commit 8455d26243
4 changed files with 11 additions and 2 deletions
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4
gdb/ChangeLog
View file

@ -1,3 +1,7 @@
2017-07-06 Pedro Alves <palves@redhat.com>
* python/py-unwind.c (pyuw_dealloc_cache): Fix for loop condition.
2017-07-04 Pedro Alves <palves@redhat.com>
* gdbtypes.c (recursive_dump_type): Don't reference TYPE_STATIC.

2
gdb/python/py-unwind.c
View file

@ -595,7 +595,7 @@ pyuw_dealloc_cache (struct frame_info *this_frame, void *cache)
TRACE_PY_UNWIND (3, "%s: enter", __FUNCTION__);
cached_frame_info *cached_frame = (cached_frame_info *) cache;
for (int i = 0; cached_frame->reg_count; i++)
for (int i = 0; i < cached_frame->reg_count; i++)
xfree (cached_frame->reg[i].data);
xfree (cache);

4
gdb/testsuite/ChangeLog
View file

@ -1,3 +1,7 @@
2017-07-06 Pedro Alves <palves@redhat.com>
* gdb.python/py-unwind.exp: Test flushregs.
2017-06-30 Sergio Durigan Junior <sergiodj@redhat.com>
PR cli/21688

3
gdb/testsuite/gdb.python/py-unwind.exp
View file

@ -51,4 +51,5 @@ gdb_test_sequence "where" "Backtrace restored by unwinder" {
"\\r\\n#2 .* main \\(.*\\) at"
}
# Check that the Python unwinder frames can be flushed / released.
gdb_test "flushregs" "Register cache flushed\\." "flush frames"