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authorAdhemerval Zanella <adhemerval.zanella@linaro.org>2021-06-25 10:54:12 -0300
committerAdhemerval Zanella <adhemerval.zanella@linaro.org>2021-07-14 15:10:27 -0300
commitba33937be210da5d07f7f01709323743f66011ce (patch)
tree8de2c3d81913a4e6b40b1f903078ce190d2f17be /elf/dl-close.c
parent0e1f068108d94576321bbbd354cfb1b3b99389bf (diff)
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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>
Diffstat (limited to 'elf/dl-close.c')
-rw-r--r--elf/dl-close.c8
1 files changed, 5 insertions, 3 deletions
diff --git a/elf/dl-close.c b/elf/dl-close.c
index 3720e47dd1..f39001cab9 100644
--- a/elf/dl-close.c
+++ b/elf/dl-close.c
@@ -77,8 +77,6 @@ remove_slotinfo (size_t idx, struct dtv_slotinfo_list *listp, size_t disp,
 	 object that wasn't fully set up.  */
       if (__glibc_likely (old_map != NULL))
 	{
-	  assert (old_map->l_tls_modid == idx);
-
 	  /* Mark the entry as unused.  These can be read concurrently.  */
 	  atomic_store_relaxed (&listp->slotinfo[idx - disp].gen,
 				GL(dl_tls_generation) + 1);
@@ -88,7 +86,11 @@ remove_slotinfo (size_t idx, struct dtv_slotinfo_list *listp, size_t disp,
       /* If this is not the last currently used entry no need to look
 	 further.  */
       if (idx != GL(dl_tls_max_dtv_idx))
-	return true;
+	{
+	  /* There is an unused dtv entry in the middle.  */
+	  GL(dl_tls_dtv_gaps) = true;
+	  return true;
+	}
     }
 
   while (idx - disp > (disp == 0 ? 1 + GL(dl_tls_static_nelem) : 0))