elf: Assign TLS modid later during dlopen [BZ #24930]

Commit a42faf59d6d9f82e5293a9ebcc26d9c9e562b12b ("Fix BZ #16634.")
attempted to fix a TLS modid consistency issue by adding additional
checks to the open_verify function.  However, this is fragile
because open_verify cannot reliably predict whether
_dl_map_object_from_fd will later fail in the more complex cases
(such as memory allocation failures).  Therefore, this commit
assigns the TLS modid as late as possible.  At that point, the link
map pointer will eventually be passed to _dl_close, which will undo
the TLS modid assignment.

Reviewed-by: Gabriel F. T. Gomes <gabrielftg@linux.ibm.com>

1 files changed, 12 insertions, 0 deletions

diff --git a/ChangeLog b/ChangeLog
index d2156e5fb0..a1da75b0f0 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,17 @@
 2019-10-04  Florian Weimer  <fweimer@redhat.com>
 
+	[BZ #24930]
+	* elf/dl-load.c (_dl_map_object_from_fd): Only assign TLS modid if
+	the link map will be returned to the caller.
+	* elf/Makefile [$(have-fpie) && $(build-shared)] (tests, tests-pie):
+	Add tst-dlopen-aout-pie.
+	(tst-tst-dlopen-aout-no-pie): Set.
+	(CFLAGS-tst-dlopen-aout-pie.c): Build with -fpie.
+	(tst-dlopen-aout-pie): Link with -ldl -lpthread.
+	* elf/tst-dlopen-aout-pie.c: New file.
+
+2019-10-04  Florian Weimer  <fweimer@redhat.com>
+
 	[BZ #24900]
 	* elf/dl-load.c (_dl_map_object_from_fd): Do not use the file ID
 	when loading the executable as part of an explicit loader