From 63c67053a3e42e9dff788de432f82ff07d4d772a Mon Sep 17 00:00:00 2001 From: "Alex Xu (Hello71)" Date: Thu, 30 Jun 2022 13:52:43 -0400 Subject: [PATCH] in early stage ldso before __dls2b, call mprotect with __syscall if LTO is enabled, gcc hoists the call to ___errno_location outside the loop even though the access to errno is gated behind head != &ldso because ___errno_location is marked __attribute__((const)). this causes the program to crash because TLS is not yet initialized when called from __dls2. this is also possible if LTO is not enabled; even though gcc 11 doesn't do it, it is still wrong to use errno here. since the start and end are already aligned, we can simply call __syscall instead of using global errno. Fixes: e13a2b8953ef ("implement PT_GNU_RELRO support") --- ldso/dynlink.c | 14 ++++++++------ 1 file changed, 8 insertions(+), 6 deletions(-) diff --git a/ldso/dynlink.c b/ldso/dynlink.c index 5b9c8be4..14fdd29e 100644 --- a/ldso/dynlink.c +++ b/ldso/dynlink.c @@ -1356,12 +1356,14 @@ static void reloc_all(struct dso *p) do_relocs(p, laddr(p, dyn[DT_REL]), dyn[DT_RELSZ], 2); do_relocs(p, laddr(p, dyn[DT_RELA]), dyn[DT_RELASZ], 3); - if (head != &ldso && p->relro_start != p->relro_end && - mprotect(laddr(p, p->relro_start), p->relro_end-p->relro_start, PROT_READ) - && errno != ENOSYS) { - error("Error relocating %s: RELRO protection failed: %m", - p->name); - if (runtime) longjmp(*rtld_fail, 1); + if (head != &ldso && p->relro_start != p->relro_end) { + long ret = __syscall(SYS_mprotect, laddr(p, p->relro_start), + p->relro_end-p->relro_start, PROT_READ); + if (ret != 0 && ret != -ENOSYS) { + error("Error relocating %s: RELRO protection failed: %m", + p->name); + if (runtime) longjmp(*rtld_fail, 1); + } } p->relocated = 1; -- 2.11.4.GIT