From: Alexandre Oliva Date: Sat, 4 Feb 2017 01:35:16 +0000 (-0500) Subject: Bug 20915: Do not initialize DTV of other threads. X-Git-Tag: glibc-2.25~5 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=d675eaf7d99096a952c1d140abfed82c939fb259;p=thirdparty%2Fglibc.git Bug 20915: Do not initialize DTV of other threads. In _dl_nothread_init_static_tls() and init_one_static_tls() we must not touch the DTV of other threads since we do not have ownership of them. The DTV need not be initialized at this point anyway since only LD/GD accesses will use them. If LD/GD accesses occur they will take care to initialize their own thread's DTV. Concurrency comments were removed from the patch since they need to be reworked along with a full description of DTV ownership and when it is or is not safe to modify these structures. Alexandre Oliva's original patch and discussion: https://sourceware.org/ml/libc-alpha/2016-09/msg00512.html --- diff --git a/ChangeLog b/ChangeLog index f70871d4eca..9ed7ff6883c 100644 --- a/ChangeLog +++ b/ChangeLog @@ -1,3 +1,12 @@ +2017-02-03 Alexandre Oliva + Florian Weimer + Carlos O'Donell + + [BZ #20915] + * elf/dl-reloc.c (_dl_nothread_init_static_tls): + Do not initialize DTV. + * nptl/allocatestack.c (init_one_static_tls): Likewise. + 2017-02-03 David S. Miller * sysdeps/sparc/sparc64/fpu/multiarch/s_fmax-vis3.S: Remove file. diff --git a/elf/dl-reloc.c b/elf/dl-reloc.c index 52311f02786..4ac558df525 100644 --- a/elf/dl-reloc.c +++ b/elf/dl-reloc.c @@ -137,12 +137,6 @@ _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/nptl/allocatestack.c b/nptl/allocatestack.c index 6402ea43f28..8a228ab2542 100644 --- a/nptl/allocatestack.c +++ b/nptl/allocatestack.c @@ -1191,11 +1191,6 @@ 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 - /* 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);