elf: Fix DTV gap reuse logic (BZ #27135)

This is updated version of the 572bd547d57a (reverted by 40ebfd016ad2)
that fixes the _dl_next_tls_modid issues.

This issue with 572bd547d57a patch is the DTV entry will be only
update on dl_open_worker() with the update_tls_slotinfo() call after
all dependencies are being processed by _dl_map_object_deps().  However
_dl_map_object_deps() itself might call _dl_next_tls_modid(), and since
the _dl_tls_dtv_slotinfo_list::map is not yet set the entry will be
wrongly reused.

This patch fixes by renaming the _dl_next_tls_modid() function to
_dl_assign_tls_modid() and by passing the link_map so it can set
the slotinfo value so a subsequente _dl_next_tls_modid() call will
see the entry as allocated.

The intermediary value is cleared up on remove_slotinfo() for the case
a library fails to load with RTLD_NOW.

This patch fixes BZ #27135.

Checked on x86_64-linux-gnu.

Reviewed-by: Szabolcs Nagy <szabolcs.nagy@arm.com>

1 files changed, 1 insertions, 1 deletions

diff --git a/elf/rtld.c b/elf/rtld.c
index e3fb2a5b2a..d733359eaf 100644
--- a/elf/rtld.c
+++ b/elf/rtld.c
@@ -1721,7 +1721,7 @@ dl_main (const ElfW(Phdr) *phdr,
   /* Add the dynamic linker to the TLS list if it also uses TLS.  */
   if (GL(dl_rtld_map).l_tls_blocksize != 0)
     /* Assign a module ID.  Do this before loading any audit modules.  */
-    GL(dl_rtld_map).l_tls_modid = _dl_next_tls_modid ();
+    _dl_assign_tls_modid (&GL(dl_rtld_map));
 
   audit_list_add_dynamic_tag (&state.audit_list, main_map, DT_AUDIT);
   audit_list_add_dynamic_tag (&state.audit_list, main_map, DT_DEPAUDIT);