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Adhemerval Zanella 99e9c5d1ca Fix assert during static startup (BZ 33326)
The BZ#33326 testcase triggers an assertion during process startup,
which results in a segmentation fault instead of an error message
and process termination with a SIGABRT.  The assert issues
__libc_message_impl, which in turn might call string functions
depending on the ABI (strchrnul, strlen, memcpy/mempcpy), system
calls (writev and mmap), and finally the abort call.

The dl-symbol-redir-ifunc.h is also expanded to cover strchrnul on
x86_64, s390, powerpc64 (both endianness) and loongarch, mempcpy on
powerpc64be, and memcpy on aarch64.  On s390 the redirection is only
issued if the ifunc variant is built, since strchrnul-c.c only renames
the C implementation to STRCHRNUL_DEFAULT when HAVE_STRCHRNUL_IFUNC is
set.

The buffer that backs up the assert message is now allocated through
_dl_mmap, which issues the syscall directly instead of calling __mmap
(setting errno on failure requires the thread pointer).

The abort call now issues __raise_direct instead of raise (the Hurd
port aliases __raise_direct to raise).

On i386, syscalls should not use the vDSO during program startup because
the thread pointer is not yet initialized.  This requires __raise_direct,
_dl_writev, and _dl_mmap to be built with I386_USE_SYSENTER set to 0.

Creating a test case is challenging. For static-pie, the assert is only
called for ill-formed ELF files on elf_get_dynamic_info and by some targets
on ELF_DYNAMIC_RELOCATE (although not all targets use assert in their
dl-machine.h).  Some targets also issue __libc_fatal on ARCH_SETUP_IREL,
but also only for ill-formatted ELF files.

The test employs a different strategy and overrides the __tunables_init
symbol, which is invoked immediately before self-relocation and TLS setup.
The test is built with -Wl,-z,muldefs to avoid linker issues.

I checked on aarch64, x86_64, i686, s390x (qemu), sparc (qemu),
mips64el (qemu), armhf, riscv, and powerpc.

Reviewed-by: Florian Weimer <fweimer@redhat.com>
2026-08-31 15:43:44 -03:00
..
2026-04-20 13:54:14 +02:00
2026-04-20 13:54:14 +02:00