[PATCH v2] RISC-V: Fix SIGSEGV of --static-pie binaries on riscv64 [BZ #33911]
daichengrong
daichengrong@iscas.ac.cn
Fri Mar 6 15:10:06 GMT 2026
This patch fixes a SIGSEGV observed in --static-pie binaries on riscv64,
as reported in BZ #33911. The root cause is a recent memset optimization
that introduced incorrect behavior when resolving symbols for static PIE
executables.
Problem:
--------
In static PIE binaries, an early call to ifunc memset could use GOT entries
that were not yet properly initialized. This results in jumping to
invalid addresses, causing SIGSEGV.
Solution:
---------
This patch ensures that GOT entries for static PIE binaries are
correctly set up before ifunc memset calls occur.
Signed-off-by: daichengrong <daichengrong@iscas.ac.cn>
---
sysdeps/riscv/cpu-features.c | 88 ++++++++++++++++++++++++++++++++++++
sysdeps/riscv/dl-machine.h | 4 +-
sysdeps/riscv/libc-start.c | 34 ++++++++++++++
3 files changed, 124 insertions(+), 2 deletions(-)
create mode 100644 sysdeps/riscv/cpu-features.c
create mode 100644 sysdeps/riscv/libc-start.c
diff --git a/sysdeps/riscv/cpu-features.c b/sysdeps/riscv/cpu-features.c
new file mode 100644
index 0000000000..56f694c31f
--- /dev/null
+++ b/sysdeps/riscv/cpu-features.c
@@ -0,0 +1,88 @@
+/* Initialize CPU feature data.
+ This file is part of the GNU C Library.
+ Copyright (C) 2026 Free Software Foundation, Inc.
+
+ The GNU C Library is free software; you can redistribute it and/or
+ modify it under the terms of the GNU Lesser General Public
+ License as published by the Free Software Foundation; either
+ version 2.1 of the License, or (at your option) any later version.
+
+ The GNU C Library is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public
+ License along with the GNU C Library; if not, see
+ <https://www.gnu.org/licenses/>. */
+
+# pragma GCC visibility push(hidden)
+#include <assert.h>
+#include <unistd.h>
+#include <ldsodefs.h>
+
+#include <dl-machine.h>
+#include <dl-debug.h>
+
+#define RESOLVE_MAP(map, scope, sym, version, flags) map
+#include "elf/dynamic-link.h"
+#include "elf/get-dynamic-info.h"
+
+/* Relocate static executable with PIE for local ifunc symbol. */
+static void
+init_cpu_features (void)
+{
+ ElfW(Addr) file_p_vaddr = 0;
+ const ElfW(Phdr) *ph, *phdr = GL(dl_phdr);
+ size_t phnum = GL(dl_phnum);
+
+ struct link_map *map = _dl_get_dl_main_map ();
+
+ for (ph = phdr; ph < &phdr[phnum]; ++ph)
+ switch (ph->p_type)
+ {
+ case PT_LOAD:
+ /* Skip the empty PT_LOAD segment at offset 0. */
+ if (ph->p_filesz != 0 && ph->p_offset == 0)
+ file_p_vaddr = ph->p_vaddr;
+ break;
+ case PT_DYNAMIC:
+ map->l_ld_readonly = (ph->p_flags & PF_W) == 0;
+ break;
+ default:
+ break;
+ }
+
+ /* Figure out the run-time load address of static PIE. */
+ ElfW(Addr) l_addr = elf_machine_load_address ();
+ map->l_addr = l_addr - file_p_vaddr;
+
+ map->l_ld = ((void *) l_addr + elf_machine_dynamic ());
+
+ elf_get_dynamic_info (map, false, true);
+
+ if ((map)->l_info[DT_PLTGOT] != NULL && (map)->l_info[DT_PLTGOT]->d_un.d_ptr != 0)
+ {
+ ElfW(Rela) *reloc = (ElfW(Rela) *)(map->l_info[DT_JMPREL]->d_un.d_val + map->l_addr);
+ ElfW(Addr) *gotplt = (ElfW(Addr) *) D_PTR (map, l_info[DT_PLTGOT]);
+
+ ElfW(Addr) * start = (ElfW(Addr) *)(gotplt + 2);
+ size_t rela_size = map->l_info[DT_PLTRELSZ]->d_un.d_val;
+ size_t num_plt_entries = rela_size / 8;
+
+ ElfW(Addr) plt_addr = (ElfW(Addr))((ElfW(Addr) *)(*start) + 4) + (ElfW(Addr))map->l_addr;
+ for (int ranges_index = 0; ranges_index < num_plt_entries; ++ranges_index)
+ {
+ ElfW(Addr) r_info = reloc->r_info;
+ if(ELFW (R_TYPE) (r_info) == R_RISCV_IRELATIVE)
+ {
+ ElfW(Addr) addr = (ElfW(Addr))map->l_addr + reloc->r_addend;
+ *start = ((ElfW(Addr) (*) (uint64_t, void *, void *)) (addr))(0, NULL, NULL);
+ }
+
+ start++;
+ reloc ++;
+ plt_addr += 16;
+ }
+ }
+}
diff --git a/sysdeps/riscv/dl-machine.h b/sysdeps/riscv/dl-machine.h
index 8c7312ad98..dfb202157c 100644
--- a/sysdeps/riscv/dl-machine.h
+++ b/sysdeps/riscv/dl-machine.h
@@ -1,5 +1,5 @@
/* Machine-dependent ELF dynamic relocation inline functions. RISC-V version.
- Copyright (C) 2011-2026 Free Software Foundation, Inc.
+ Copyright (C) 2011-2025 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
@@ -26,7 +26,7 @@
#include <sys/asm.h>
#include <dl-tls.h>
#include <dl-irel.h>
-#include <dl-static-tls.h>
+#include <elf/dl-static-tls.h>
#include <dl-machine-rel.h>
#ifndef _RTLD_PROLOGUE
diff --git a/sysdeps/riscv/libc-start.c b/sysdeps/riscv/libc-start.c
new file mode 100644
index 0000000000..5584ce165f
--- /dev/null
+++ b/sysdeps/riscv/libc-start.c
@@ -0,0 +1,34 @@
+/* Override csu/libc-start.c on riscv.
+ Copyright (C) 2026 Free Software Foundation, Inc.
+ This file is part of the GNU C Library.
+
+ The GNU C Library is free software; you can redistribute it and/or
+ modify it under the terms of the GNU Lesser General Public
+ License as published by the Free Software Foundation; either
+ version 2.1 of the License, or (at your option) any later version.
+
+ The GNU C Library is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public
+ License along with the GNU C Library; if not, see
+ <https://www.gnu.org/licenses/>. */
+
+# if ENABLE_STATIC_PIE
+#ifndef SHARED
+/* Relocate local IFUNC symbols in static PIE for early self relocation. */
+# if BUILD_PIE_DEFAULT
+# pragma GCC visibility push(hidden)
+# endif
+
+# include <startup.h>
+# include <ldsodefs.h>
+# include <cpu-features.c>
+
+# define ARCH_INIT_CPU_FEATURES() init_cpu_features()
+
+#endif /* !SHARED */
+#endif
+#include <csu/libc-start.c>
--
2.25.1
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