fix misalignment of dtv in static-linked programs with odd-sized TLS

both static and dynamic linked versions of the __copy_tls function
have a hidden assumption that the alignment of the beginning or end of
the memory passed is suitable for storing an array of pointers for the
dtv. pthread_create satisfies this requirement except when
libc.tls_size is misaligned, which cannot happen with dynamic linking
due to way update_tls_size computes the total size, but could happen
with static linking and odd-sized TLS.

diff --git a/src/env/__init_tls.c b/src/env/__init_tls.c
index b4df2ba58b9f265b243726de410baef9cda11a78..73551e6c4173af5976c3084a728efc4707d8e0a3 100644 (file)
--- a/src/env/__init_tls.c
+++ b/src/env/__init_tls.c
@@ -95,7 +95,8 @@ void __init_tls(size_t *aux)
        T.size += (-T.size - (uintptr_t)T.image) & (T.align-1);
        if (T.align < MIN_TLS_ALIGN) T.align = MIN_TLS_ALIGN;
 
-       libc.tls_size = 2*sizeof(void *)+T.size+T.align+sizeof(struct pthread);
+       libc.tls_size = 2*sizeof(void *)+T.size+T.align+sizeof(struct pthread)
+               + MIN_TLS_ALIGN-1 & -MIN_TLS_ALIGN;
 
        if (libc.tls_size > sizeof builtin_tls) {
 #ifndef SYS_mmap2