From 17af5da98cd2c9ec958421ae2108f877e0945451 Mon Sep 17 00:00:00 2001 From: Alexandre Oliva Date: Wed, 21 Sep 2016 22:01:16 -0300 Subject: [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. --- ChangeLog | 8 ++++++++ elf/dl-reloc.c | 6 ++++++ elf/dl-tls.c | 4 ++++ nptl/allocatestack.c | 9 ++++++--- 4 files changed, 24 insertions(+), 3 deletions(-) diff --git a/ChangeLog b/ChangeLog index abd699536b..0fe5350c97 100644 --- a/ChangeLog +++ b/ChangeLog @@ -1,3 +1,11 @@ +2016-09-21 Alexandre Oliva + + [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. + 2016-09-22 Samuel Thibault * hurd/hurdmalloc.c (malloc_fork_prepare): Rename to 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', diff --git a/nptl/allocatestack.c b/nptl/allocatestack.c index 60b34dc6fc..3016a2ed5c 100644 --- a/nptl/allocatestack.c +++ b/nptl/allocatestack.c @@ -1207,9 +1207,12 @@ init_one_static_tls (struct pthread *curp, struct link_map *map) # error "Either TLS_TCB_AT_TP or TLS_DTV_AT_TP must be defined" # endif - /* We cannot delay the initialization of the Static TLS area, since - it can be accessed with LE or IE, but since the DTV is only used - by GD and LD, we can delay its update to avoid a race. */ + /* Fill in the DTV slot so that a later LD/GD access will find it. */ + dtv_t *dtv = GET_DTV (TLS_TPADJ (curp)); + 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); } -- cgit v1.2.3