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rtld: Round down relro_size

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lld rounds up p_memsz(PT_GNU_RELRO) to satisfy common-page-size. If the
page size is smaller than common-page-size, rounding up relro_size may
incorrectly make some RW pages read-only.

GNU ld, gold, and ld.lld ensures p_vaddr+p_memsz is a multiple of
common-page-size. While max-page-size >= system the page size,
common-page-size can be smaller than the system page size.

Submitted by:	MaskRay
MFC after:	1 week
Differential revision:	https://reviews.freebsd.org/D31498
This commit is contained in:
Konstantin Belousov 2021-08-12 05:45:15 +03:00
parent 44d4804d19
commit c9f833abf1
2 changed files with 4 additions and 2 deletions
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3
libexec/rtld-elf/map_object.c
View File

@ -325,7 +325,8 @@ map_object(int fd, const char *path, const struct stat *sb)
}
obj->stack_flags = stack_flags;
obj->relro_page = obj->relocbase + trunc_page(relro_page);
obj->relro_size = round_page(relro_size);
obj->relro_size = trunc_page(relro_page + relro_size) -
trunc_page(relro_page);
if (note_start < note_end)
digest_notes(obj, note_start, note_end);
if (note_map != NULL)

3
libexec/rtld-elf/rtld.c
View File

@ -1557,7 +1557,8 @@ digest_phdr(const Elf_Phdr *phdr, int phnum, caddr_t entry, const char *path)
case PT_GNU_RELRO:
obj->relro_page = obj->relocbase + trunc_page(ph->p_vaddr);
obj->relro_size = round_page(ph->p_memsz);
obj->relro_size = trunc_page(ph->p_vaddr + ph->p_memsz) -
trunc_page(ph->p_vaddr);
break;
case PT_NOTE: