From 48699da1c468543ade14777819bd1b4d652709de Mon Sep 17 00:00:00 2001 From: Florian Weimer Date: Sun, 12 Jul 2020 17:53:58 +0200 Subject: [PATCH] elf: Support at least 32-byte alignment in static dlopen Otherwise loading a dynamically linked libc with rseq support fails, as result of the __rseq_abi TLS variable, which has an alignment of 32 bytes. Reviewed-by: Carlos O'Donell Tested-by: Vineet Gupta Reviewed-by: Alistair Francis Tested-by: Alistair Francis --- csu/libc-tls.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/csu/libc-tls.c b/csu/libc-tls.c index 06e76bd..3f1655f 100644 --- a/csu/libc-tls.c +++ b/csu/libc-tls.c @@ -112,6 +112,12 @@ __libc_setup_tls (void) size_t tcb_offset; const ElfW(Phdr) *phdr; + /* libc.so with rseq has TLS with 32-byte alignment. Static dlopen + requires at least 32-byte alignment as well, otherwise loading + libc.so will always fail. */ + if (max_align < 32) + max_align = 32; + struct link_map *main_map = GL(dl_ns)[LM_ID_BASE]._ns_loaded; /* Look through the TLS segment if there is any. */ -- 2.7.4