ld.so: be more mmap()-behaviour-independent
. if the layout of virtual address regions as returned by mmap() without a location hint changes, ld.so could trip itself up (under minix). this change allocates the full size it needs for every object that's loaded so that if that succeeds, it's sure there's virtual address space for the whole thing no matter what other bits happen to be there already. . this fix exposed a bug in the test; at atexit() execution time the loaded object is unmapped, so that part of the test is removed.
This commit is contained in:
Ben Gras
parent
3f40eb3511
commit
6a6b7b5769
2 changed files with 35 additions and 47 deletions
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@ -38,6 +38,7 @@ __RCSID("$NetBSD: map_object.c,v 1.41 2010/10/16 10:27:07 skrll Exp $");
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#endif /* not lint */
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#include <errno.h>
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#include <stdio.h>
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#include <stddef.h>
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#include <stdlib.h>
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#include <string.h>
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@ -49,55 +50,27 @@ __RCSID("$NetBSD: map_object.c,v 1.41 2010/10/16 10:27:07 skrll Exp $");
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#include "debug.h"
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#include "rtld.h"
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#ifdef __minix
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#define munmap minix_munmap
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#endif
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#define MINIXVERBOSE 0
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static int protflags(int); /* Elf flags -> mmap protection */
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#define EA_UNDEF (~(Elf_Addr)0)
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#ifdef __minix
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#define mmap minix_mmap_emulator
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#define munmap minix_munmap
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/* for minix, ignore MAP_SHARED and MAP_FILE for now. */
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#define MAP_SHARED 0
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#define MAP_FILE 0
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#endif
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#undef MINIXVERBOSE
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static void * minix_mmap_emulator(void *addrhint, size_t size, int prot, int flags, int fd, off_t off)
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static void Pread(void *addr, size_t size, int fd, off_t off)
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{
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void *ret;
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int mapflags;
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size_t s;
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mapflags = flags & (MAP_FIXED);
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#ifdef MINIXVERBOSE
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if(addrhint) {
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fprintf(stderr, "0x%lx-0x%lx requested\n", addrhint,
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(char *) addrhint + size);
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int s;
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if((s=pread(fd,addr, size, off)) < 0) {
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_rtld_error("pread failed");
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exit(1);
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}
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#if MINIXVERBOSE
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fprintf(stderr, "read 0x%lx bytes from offset 0x%lx to addr 0x%lx\n", size, off, addr);
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#endif
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if((ret = minix_mmap(addrhint, size, PROT_READ|PROT_WRITE,
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MAP_ANON|MAP_PRIVATE|MAP_PREALLOC|mapflags, -1, 0)) == MAP_FAILED) {
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return ret;
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}
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if(!(mapflags & MAP_ANON)) {
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if((s=pread(fd, ret, size, off)) <= 0) {
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munmap(ret, size);
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return MAP_FAILED;
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}
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}
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#ifdef MINIXVERBOSE
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fprintf(stderr, "0x%lx-0x%lx mapped\n",
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ret, (char *) ret + size);
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#endif
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return ret;
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}
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/*
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@ -159,8 +132,17 @@ _rtld_map_object(const char *path, int fd, const struct stat *sb)
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obj->ino = sb->st_ino;
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}
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#ifdef __minix
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ehdr = minix_mmap(NULL, _rtld_pagesz, PROT_READ|PROT_WRITE,
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MAP_PREALLOC|MAP_ANON, -1, (off_t)0);
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Pread(ehdr, _rtld_pagesz, fd, 0);
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#if MINIXVERBOSE
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fprintf(stderr, "minix mmap for header: 0x%lx\n", ehdr);
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#endif
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#else
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ehdr = mmap(NULL, _rtld_pagesz, PROT_READ, MAP_FILE | MAP_SHARED, fd,
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(off_t)0);
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#endif
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obj->ehdr = ehdr;
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if (ehdr == MAP_FAILED) {
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_rtld_error("%s: read error: %s", path, xstrerror(errno));
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@ -349,9 +331,12 @@ _rtld_map_object(const char *path, int fd, const struct stat *sb)
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mapbase = mmap(base_addr, mapsize, text_flags,
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mapflags | MAP_FILE | MAP_PRIVATE, fd, base_offset);
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#else
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/* minix doesn't want overlapping mmap()s */
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mapbase = mmap(base_addr, obj->textsize, text_flags,
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mapflags | MAP_FILE | MAP_PRIVATE, fd, base_offset);
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mapbase = minix_mmap(base_addr, mapsize, PROT_READ|PROT_WRITE,
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MAP_ANON | MAP_PREALLOC, -1, 0);
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#if MINIXVERBOSE
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fprintf(stderr, "minix mmap for whole block: 0x%lx-0x%lx\n", mapbase, mapbase+mapsize);
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#endif
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Pread(mapbase, obj->textsize, fd, 0);
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#endif
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if (mapbase == MAP_FAILED) {
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_rtld_error("mmap of entire address space failed: %s",
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@ -361,13 +346,18 @@ _rtld_map_object(const char *path, int fd, const struct stat *sb)
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/* Overlay the data segment onto the proper region. */
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data_addr = mapbase + (data_vaddr - base_vaddr);
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#ifdef __minix
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Pread(data_addr, data_vlimit - data_vaddr, fd, data_offset);
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#else
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if (mmap(data_addr, data_vlimit - data_vaddr, data_flags,
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MAP_FILE | MAP_PRIVATE | MAP_FIXED, fd, data_offset) ==
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MAP_FAILED) {
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_rtld_error("mmap of data failed: %s", xstrerror(errno));
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goto bad;
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}
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#endif
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#ifndef __minix
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bsssize= base_vlimit - data_vlimit;
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if(bsssize > 0) {
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/* Overlay the bss segment onto the proper region. */
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@ -384,7 +374,6 @@ _rtld_map_object(const char *path, int fd, const struct stat *sb)
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gap_addr = mapbase + round_up(text_vlimit - base_vaddr);
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gap_size = data_addr - gap_addr;
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#ifndef __minix
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if (gap_size != 0 && mprotect(gap_addr, gap_size, PROT_NONE) == -1) {
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_rtld_error("mprotect of text -> data gap failed: %s",
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xstrerror(errno));
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@ -18,7 +18,6 @@ long modfunction(long v1, long *argcookie, long v2) {
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}
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*argcookie = MAGIC3;
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cookie = MAGIC2;
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atexit(exithandler);
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return MAGIC1;
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}
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