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When allocating the entire address space of an object, map an anonymous 

region first (using the data/bss protection) covering it, then overlay
the text and data regions at the appropriate offsets within the region,
and then unmap any gap between the text and data.

The previous method of maping the entire address space with the actual
file object itself is incorrect, as it may extend past the end of the
file if the section alignment is large enough.

This bug was the source of the libposix failure on the SPARC and another
similar failure (with libc!) on the Alpha (failure was accompanied by
a "uvn_io: size check fired" message on the console).
This commit is contained in:
thorpej 1999-08-06 22:33:49 +00:00
parent a7361f3acf
commit 5c5817ee4a
1 changed files with 40 additions and 26 deletions
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66
libexec/ld.elf_so/map_object.c
View File

@ -1,4 +1,4 @@
/* $NetBSD: map_object.c,v 1.4 1999/03/01 16:40:07 christos Exp $ */
/* $NetBSD: map_object.c,v 1.5 1999/08/06 22:33:49 thorpej Exp $ */
/*
* Copyright 1996 John D. Polstra.
@ -77,18 +77,18 @@ _rtld_map_object(path, fd)
Elf_Off base_offset;
Elf_Addr base_vaddr;
Elf_Addr base_vlimit;
Elf_Addr text_vlimit;
caddr_t base_addr;
Elf_Off data_offset;
Elf_Addr data_vaddr;
Elf_Addr data_vlimit;
caddr_t data_addr;
caddr_t gap_addr;
size_t gap_size;
#ifdef RTLD_LOADER
Elf_Addr clear_vaddr;
caddr_t clear_addr;
size_t nclear;
Elf_Addr bss_vaddr;
Elf_Addr bss_vlimit;
caddr_t bss_addr;
#endif
if ((nbytes = read(fd, u.buf, PAGESIZE)) == -1) {
@ -177,9 +177,14 @@ _rtld_map_object(path, fd)
#endif
/*
* Map the entire address space of the object, to stake out our
* contiguous region, and to establish the base address for relocation.
*/
* Map the entire address space of the object as an anonymous
* region to stake out our contiguous region and establish a
* base for relocation.
*
* We map it using the data/BSS protection, then overlay bits
* of the file over the top, and unmap the gaps left by padding
* to alignment.
*/
base_offset = round_down(segs[0]->p_offset);
base_vaddr = round_down(segs[0]->p_vaddr);
base_vlimit = round_up(segs[1]->p_vaddr + segs[1]->p_memsz);
@ -190,19 +195,30 @@ _rtld_map_object(path, fd)
base_addr = NULL;
#endif
mapbase = mmap(base_addr, mapsize, protflags(segs[0]->p_flags),
MAP_FILE | MAP_PRIVATE, fd, base_offset);
if (mapbase == (caddr_t) - 1) {
mapbase = mmap(base_addr, mapsize, protflags(segs[1]->p_flags),
MAP_ANON | MAP_PRIVATE, -1, (off_t) 0);
if (mapbase == MAP_FAILED) {
_rtld_error("mmap of entire address space failed: %s",
xstrerror(errno));
return NULL;
}
if (base_addr != NULL && mapbase != base_addr) {
_rtld_error("mmap returned wrong address: wanted %p, got %p", base_addr,
mapbase);
_rtld_error("mmap returned wrong address: wanted %p, got %p",
base_addr, mapbase);
munmap(mapbase, mapsize);
return NULL;
}
base_addr = mapbase;
/* Overlay the text segment onto the proper region. */
text_vlimit = round_up(segs[0]->p_vaddr + segs[0]->p_memsz);
if (mmap(base_addr, text_vlimit - base_vaddr,
protflags(segs[0]->p_flags), MAP_FILE | MAP_PRIVATE | MAP_FIXED,
fd, base_offset) == MAP_FAILED) {
_rtld_error("mmap of text failed: %s", xstrerror(errno));
return NULL;
}
/* Overlay the data segment onto the proper region. */
data_offset = round_down(segs[1]->p_offset);
data_vaddr = round_down(segs[1]->p_vaddr);
@ -210,10 +226,20 @@ _rtld_map_object(path, fd)
data_addr = mapbase + (data_vaddr - base_vaddr);
if (mmap(data_addr, data_vlimit - data_vaddr,
protflags(segs[1]->p_flags), MAP_FILE | MAP_PRIVATE | MAP_FIXED,
fd, data_offset) == (caddr_t)-1) {
fd, data_offset) == MAP_FAILED) {
_rtld_error("mmap of data failed: %s", xstrerror(errno));
return NULL;
}
/* Unmap the gap between the text and data. */
gap_addr = base_addr + round_up(text_vlimit - base_vaddr);
gap_size = data_addr - gap_addr;
if (gap_size != 0 && munmap(gap_addr, gap_size) == -1) {
_rtld_error("munmap of text -> data gap failed: %s",
xstrerror(errno));
return NULL;
}
#ifdef RTLD_LOADER
/* Clear any BSS in the last page of the data segment. */
clear_vaddr = segs[1]->p_vaddr + segs[1]->p_filesz;
@ -221,19 +247,7 @@ _rtld_map_object(path, fd)
if ((nclear = data_vlimit - clear_vaddr) > 0)
memset(clear_addr, 0, nclear);
/* Overlay the BSS segment onto the proper region. */
bss_vaddr = data_vlimit;
bss_vlimit = round_up(segs[1]->p_vaddr + segs[1]->p_memsz);
bss_addr = mapbase + (bss_vaddr - base_vaddr);
if (bss_vlimit > bss_vaddr) { /* There is something to do */
if (mmap(bss_addr, bss_vlimit - bss_vaddr,
protflags(segs[1]->p_flags),
MAP_ANON | MAP_PRIVATE | MAP_FIXED, -1,
0) == (caddr_t)-1) {
_rtld_error("mmap of bss failed: %s", xstrerror(errno));
return NULL;
}
}
/* Non-file portion of BSS mapped above. */
#endif
obj = CNEW(Obj_Entry);