From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: by sourceware.org (Postfix, from userid 1944) id 3F32E3857815; Wed, 4 May 2022 06:00:47 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 3F32E3857815 Content-Type: text/plain; charset="us-ascii" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit From: Szabolcs Nagy To: glibc-cvs@sourceware.org Subject: [glibc/nsz/bug23293] elf: Move post-relocation code of _dl_start into _dl_start_final X-Act-Checkin: glibc X-Git-Author: Fangrui Song X-Git-Refname: refs/heads/nsz/bug23293 X-Git-Oldrev: 33e03f9cd2be4f2cd62f93fda539cc07d9c8130e X-Git-Newrev: 1305edd42c44fee6f8660734d2dfa4911ec755d6 Message-Id: <20220504060047.3F32E3857815@sourceware.org> Date: Wed, 4 May 2022 06:00:47 +0000 (GMT) X-BeenThere: glibc-cvs@sourceware.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Glibc-cvs mailing list List-Unsubscribe: , List-Archive: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 04 May 2022 06:00:47 -0000 https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=1305edd42c44fee6f8660734d2dfa4911ec755d6 commit 1305edd42c44fee6f8660734d2dfa4911ec755d6 Author: Fangrui Song Date: Mon Apr 25 10:30:26 2022 -0700 elf: Move post-relocation code of _dl_start into _dl_start_final On non-PI_STATIC_AND_HIDDEN architectures, getting the address of _rtld_local_ro (for GLRO (dl_final_object)) goes through a GOT entry. The GOT load may be reordered before self relocation, leading to an unrelocated/incorrect _rtld_local_ro address. 84e02af1ebc9988126eebe60bf19226cea835623 tickled GCC powerpc32 to reorder the GOT load before relative relocations, leading to ld.so crash. This is similar to the m68k jump table reordering issue fixed by a8e9b5b8079d18116ca69c9797e77804ecf2ee7e. Move code after self relocation into _dl_start_final to avoid the reordering. This fixes powerpc32 and may help other architectures when ELF_DYNAMIC_RELOCATE is simplified in the future. Diff: --- elf/rtld.c | 25 ++++++++++--------------- 1 file changed, 10 insertions(+), 15 deletions(-) diff --git a/elf/rtld.c b/elf/rtld.c index 19e328f89e..93180466d6 100644 --- a/elf/rtld.c +++ b/elf/rtld.c @@ -468,6 +468,10 @@ _dl_start_final (void *arg, struct dl_start_final_info *info) { ElfW(Addr) start_addr; + /* Do not use an initializer for these members because it would + intefere with __rtld_static_init. */ + GLRO (dl_find_object) = &_dl_find_object; + /* If it hasn't happen yet record the startup time. */ rtld_timer_start (&start_time); #if !defined DONT_USE_BOOTSTRAP_MAP @@ -512,7 +516,10 @@ _dl_start_final (void *arg, struct dl_start_final_info *info) print_statistics (RTLD_TIMING_REF(rtld_total_time)); } - return start_addr; +#ifndef ELF_MACHINE_START_ADDRESS +# define ELF_MACHINE_START_ADDRESS(map, start) (start) +#endif + return ELF_MACHINE_START_ADDRESS (GL(dl_ns)[LM_ID_BASE]._ns_loaded, start_addr); } #ifdef DONT_USE_BOOTSTRAP_MAP @@ -586,23 +593,11 @@ _dl_start (void *arg) __rtld_malloc_init_stubs (); - /* Do not use an initializer for these members because it would - intefere with __rtld_static_init. */ - GLRO (dl_find_object) = &_dl_find_object; - - { #ifdef DONT_USE_BOOTSTRAP_MAP - ElfW(Addr) entry = _dl_start_final (arg); + return _dl_start_final (arg); #else - ElfW(Addr) entry = _dl_start_final (arg, &info); + return _dl_start_final (arg, &info); #endif - -#ifndef ELF_MACHINE_START_ADDRESS -# define ELF_MACHINE_START_ADDRESS(map, start) (start) -#endif - - return ELF_MACHINE_START_ADDRESS (GL(dl_ns)[LM_ID_BASE]._ns_loaded, entry); - } }