[pushed] Avoid zero-length array at the end of struct link_map [BZ #25097]
Commit Message
Sourceware to Gerrit sync has submitted this change.
Change URL: https://gnutoolchain-gerrit.osci.io/r/c/glibc/+/488
......................................................................
Avoid zero-length array at the end of struct link_map [BZ #25097]
l_audit ends up as an internal array with _rtld_global, and GCC 10
warns about this.
This commit does not change the layout of _rtld_global, so it is
suitable for backporting. Future changes could allocate more of the
audit state dynamically and remove it from always-allocated data
structures, to optimize the common case of inactive auditing.
Change-Id: Ic911100730f9124d4ea977ead8e13cee64b84d45
---
M include/link.h
M sysdeps/generic/ldsodefs.h
2 files changed, 23 insertions(+), 12 deletions(-)
Approvals:
Carlos O'Donell: Looks good to me, approved
@@ -325,16 +325,18 @@
size_t l_relro_size;
unsigned long long int l_serial;
-
- /* Audit information. This array apparent must be the last in the
- structure. Never add something after it. */
- struct auditstate
- {
- uintptr_t cookie;
- unsigned int bindflags;
- } l_audit[0];
};
+/* Information used by audit modules. For most link maps, this data
+ immediate follows the link map in memory. For the dynamic linker,
+ it is allocated separately. See link_map_audit_state in
+ <ldsodefs.h>. */
+struct auditstate
+{
+ uintptr_t cookie;
+ unsigned int bindflags;
+};
+
#if __ELF_NATIVE_CLASS == 32
# define symbind symbind32
@@ -379,11 +379,12 @@
/* List of search directories. */
EXTERN struct r_search_path_elem *_dl_all_dirs;
- /* Structure describing the dynamic linker itself. We need to
- reserve memory for the data the audit libraries need. */
+ /* Structure describing the dynamic linker itself. */
EXTERN struct link_map _dl_rtld_map;
#ifdef SHARED
- struct auditstate audit_data[DL_NNS];
+ /* Used to store the audit information for the link map of the
+ dynamic loader. */
+ struct auditstate _dl_rtld_auditstate[DL_NNS];
#endif
#if defined SHARED && defined _LIBC_REENTRANT \
@@ -1178,7 +1179,15 @@
static inline struct auditstate *
link_map_audit_state (struct link_map *l, size_t index)
{
- return &l->l_audit[index];
+ if (l == &GL (dl_rtld_map))
+ /* The auditstate array is stored separately. */
+ return &GL (dl_rtld_auditstate) [index];
+ else
+ {
+ /* The auditstate array follows the link map in memory. */
+ struct auditstate *base = (struct auditstate *) (l + 1);
+ return &base[index];
+ }
}
#endif /* SHARED */