[PATCH 1/3] treat null vdso base same as missing

[Bobby Bingham <koorogi@koorogi.info>]

On s390x, the kernel provides AT_SYSINFO_EHDR, but sets it to zero, if the
program being run does not have a program interpreter.  This causes
problems when running the dynamic linker directly.
---
 ldso/dynlink.c      | 2 +-
 src/internal/vdso.c | 1 +
 2 files changed, 2 insertions(+), 1 deletion(-)

diff --git a/ldso/dynlink.c b/ldso/dynlink.c
index e458f38..5a9e2ba 100644
--- a/ldso/dynlink.c
+++ b/ldso/dynlink.c
@@ -1549,7 +1549,7 @@ _Noreturn void __dls3(size_t *sp)
 	}
 
 	/* Attach to vdso, if provided by the kernel */
-	if (search_vec(auxv, &vdso_base, AT_SYSINFO_EHDR)) {
+	if (search_vec(auxv, &vdso_base, AT_SYSINFO_EHDR) && vdso_base) {
 		Ehdr *ehdr = (void *)vdso_base;
 		Phdr *phdr = vdso.phdr = (void *)(vdso_base + ehdr->e_phoff);
 		vdso.phnum = ehdr->e_phnum;
diff --git a/src/internal/vdso.c b/src/internal/vdso.c
index 6ae0212..ff392bc 100644
--- a/src/internal/vdso.c
+++ b/src/internal/vdso.c
@@ -44,6 +44,7 @@ void *__vdsosym(const char *vername, const char *name)
 	size_t i;
 	for (i=0; libc.auxv[i] != AT_SYSINFO_EHDR; i+=2)
 		if (!libc.auxv[i]) return 0;
+	if (!libc.auxv[i+1]) return 0;
 	Ehdr *eh = (void *)libc.auxv[i+1];
 	Phdr *ph = (void *)((char *)eh + eh->e_phoff);
 	size_t *dynv=0, base=-1;
-- 
2.9.0