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authorAlexandre Oliva <aoliva@redhat.com>2016-09-21 22:01:16 -0300
committerAlexandre Oliva <aoliva@redhat.com>2016-09-21 22:01:16 -0300
commit17af5da98cd2c9ec958421ae2108f877e0945451 (patch)
tree6f1e45cb0947ef6c28d931f9c07b5a0f1292885c /elf
parent444eacba82f675d4657ad55da67b355536be90ab (diff)
downloadglibc-17af5da98cd2c9ec958421ae2108f877e0945451.tar.gz
[PR19826] fix non-LE TLS in static programs
An earlier fix for TLS dropped early initialization of DTV entries for modules using static TLS, leaving it for __tls_get_addr to set them up. That worked on platforms that require the GD access model to be relaxed to LE in the main executable, but it caused a regression on platforms that allow GD in the main executable, particularly in statically-linked programs: they use a custom __tls_get_addr that does not update the DTV, which fails when the DTV early initialization is not performed. In static programs, __libc_setup_tls performs the DTV initialization for the main thread, but the DTV of other threads is set up in _dl_allocate_tls_init, so that's the fix that matters. Restoring the initialization in the remaining functions modified by this patch was just for uniformity. It's not clear that it is ever needed: even on platforms that allow GD in the main executable, the dynamically-linked version of __tls_get_addr would set up the DTV entries, even for static TLS modules, while updating the DTV counter. for ChangeLog [BZ #19826] * elf/dl-tls.c (_dl_allocate_tls_init): Restore DTV early initialization of static TLS entries. * elf/dl-reloc.c (_dl_nothread_init_static_tls): Likewise. * nptl/allocatestack.c (init_one_static_tls): Likewise.
Diffstat (limited to 'elf')
-rw-r--r--elf/dl-reloc.c6
-rw-r--r--elf/dl-tls.c4
2 files changed, 10 insertions, 0 deletions
diff --git a/elf/dl-reloc.c b/elf/dl-reloc.c
index 42bddc1e2c..dcab666d56 100644
--- a/elf/dl-reloc.c
+++ b/elf/dl-reloc.c
@@ -137,6 +137,12 @@ _dl_nothread_init_static_tls (struct link_map *map)
# error "Either TLS_TCB_AT_TP or TLS_DTV_AT_TP must be defined"
#endif
+ /* Fill in the DTV slot so that a later LD/GD access will find it. */
+ dtv_t *dtv = THREAD_DTV ();
+ assert (map->l_tls_modid <= dtv[-1].counter);
+ dtv[map->l_tls_modid].pointer.to_free = NULL;
+ dtv[map->l_tls_modid].pointer.val = dest;
+
/* Initialize the memory. */
memset (__mempcpy (dest, map->l_tls_initimage, map->l_tls_initimage_size),
'\0', map->l_tls_blocksize - map->l_tls_initimage_size);
diff --git a/elf/dl-tls.c b/elf/dl-tls.c
index 17567ad1b3..60f4c1da5c 100644
--- a/elf/dl-tls.c
+++ b/elf/dl-tls.c
@@ -538,6 +538,10 @@ _dl_allocate_tls_init (void *result)
# error "Either TLS_TCB_AT_TP or TLS_DTV_AT_TP must be defined"
#endif
+ /* Set up the DTV entry. The simplified __tls_get_addr that
+ some platforms use in static programs requires it. */
+ dtv[map->l_tls_modid].pointer.val = dest;
+
/* Copy the initialization image and clear the BSS part. */
memset (__mempcpy (dest, map->l_tls_initimage,
map->l_tls_initimage_size), '\0',