[pushed] Fix double-free corruption
Commit Message
Fixes a double-free regression introduced by commit b7b030adc405
("Return unique_xmalloc_ptr from target_read_stralloc"):
gdb.sum:
Running src/gdb/testsuite/gdb.base/catch-syscall.exp ...
ERROR: Process no longer exists
Valgrind shows:
(gdb) catch syscall
==3687== Thread 1:
==3687== Invalid free() / delete / delete[] / realloc()
==3687== at 0x4C29CF0: free (vg_replace_malloc.c:530)
==3687== by 0x610862: xfree(void*) (common-utils.c:101)
==3687== by 0x440D5D: gdb::xfree_deleter<char>::operator()(char*) const (gdb_unique_ptr.h:34)
==3687== by 0x446CC6: std::unique_ptr<char, gdb::xfree_deleter<char> >::reset(char*) (unique_ptr.h:344)
==3687== by 0x81BE50: xml_fetch_content_from_file(char const*, void*) (xml-support.c:1042)
==3687== by 0x81DA86: xml_init_syscalls_info(char const*) (xml-syscall.c:366)
==3687== by 0x81DBDD: init_syscalls_info(gdbarch*) (xml-syscall.c:398)
==3687== by 0x81E131: get_syscall_by_number(gdbarch*, int, syscall*) (xml-syscall.c:599)
==3687== by 0x5BE86F: catch_syscall_command_1(char*, int, cmd_list_element*) (break-catch-syscall.c:481)
==3687== by 0x4B46B1: do_sfunc(cmd_list_element*, char*, int) (cli-decode.c:138)
==3687== by 0x4B76B8: cmd_func(cmd_list_element*, char*, int) (cli-decode.c:1952)
==3687== by 0x7E91C7: execute_command(char*, int) (top.c:615)
==3687== Address 0x14332ae0 is 0 bytes inside a block of size 4,096 free'd
==3687== at 0x4C2AB8B: realloc (vg_replace_malloc.c:785)
==3687== by 0x610792: xrealloc (common-utils.c:62)
==3687== by 0x81BE3E: xml_fetch_content_from_file(char const*, void*) (xml-support.c:1042)
==3687== by 0x81DA86: xml_init_syscalls_info(char const*) (xml-syscall.c:366)
==3687== by 0x81DBDD: init_syscalls_info(gdbarch*) (xml-syscall.c:398)
==3687== by 0x81E131: get_syscall_by_number(gdbarch*, int, syscall*) (xml-syscall.c:599)
==3687== by 0x5BE86F: catch_syscall_command_1(char*, int, cmd_list_element*) (break-catch-syscall.c:481)
==3687== by 0x4B46B1: do_sfunc(cmd_list_element*, char*, int) (cli-decode.c:138)
==3687== by 0x4B76B8: cmd_func(cmd_list_element*, char*, int) (cli-decode.c:1952)
==3687== by 0x7E91C7: execute_command(char*, int) (top.c:615)
==3687== by 0x6A422D: command_handler(char*) (event-top.c:583)
==3687== by 0x6A45F2: command_line_handler(char*) (event-top.c:773)
[...]
The problem is that if xrealloc decides it needs a new memory block,
it frees the previous block/pointer, and then text.reset() frees it
again.
gdb/ChangeLog:
2017-10-17 Pedro Alves <palves@redhat.com>
* xml-support.c (xml_fetch_content_from_file): Call
unique_ptr::release() instead unique_ptr::get() when passing
through xrealloc.
---
gdb/ChangeLog | 6 ++++++
gdb/xml-support.c | 2 +-
2 files changed, 7 insertions(+), 1 deletion(-)
@@ -1,3 +1,9 @@
+2017-10-17 Pedro Alves <palves@redhat.com>
+
+ * xml-support.c (xml_fetch_content_from_file): Call
+ unique_ptr::release() instead unique_ptr::get() when passing
+ through xrealloc.
+
2017-10-17 Yao Qi <yao.qi@linaro.org>
* regcache.c (regcache::xfer_part): Remove parameters read and
@@ -1039,7 +1039,7 @@ xml_fetch_content_from_file (const char *filename, void *baton)
break;
len = len * 2;
- text.reset ((char *) xrealloc (text.get (), len));
+ text.reset ((char *) xrealloc (text.release (), len));
}
text.get ()[offset] = '\0';