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fix missing bss handling in FDPIC ELF loader 

when a library being loaded has bss (i.e. data segment with
p_memsz>p_filesz), this region needs to be zeroed with a combination
of memset and/or mmap. the regular ELF loader always did this but the
FDPIC code path omitted it, leading to objects in bss having
uninitialized/junk contents.
This commit is contained in:
Rich Felker 2015-10-28 21:45:31 -04:00
parent 6eada2edb3
commit fead7e3fc0
1 changed files with 13 additions and 0 deletions
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13
src/ldso/dynlink.c
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@ -604,6 +604,19 @@ static void *map_library(int fd, struct dso *dso)
dso->loadmap->segs[i].p_vaddr = ph->p_vaddr;
dso->loadmap->segs[i].p_memsz = ph->p_memsz;
i++;
if (prot & PROT_WRITE) {
size_t brk = (ph->p_vaddr & PAGE_SIZE-1)
+ ph->p_filesz;
size_t pgbrk = brk + PAGE_SIZE-1 & -PAGE_SIZE;
size_t pgend = brk + ph->p_memsz - ph->p_filesz
+ PAGE_SIZE-1 & -PAGE_SIZE;
if (pgend > pgbrk && mmap_fixed(map+pgbrk,
pgend-pgbrk, prot,
MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS,
-1, off_start) == MAP_FAILED)
goto error;
memset(map + brk, 0, pgbrk-brk);
}
}
map = (void *)dso->loadmap->segs[0].addr;
map_len = 0;