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Zero the tail of last RW page, even when variable page size

Browse Source 
https://github.com/upx/upx/issues/611
	modified:   stub/src/amd64-linux.elf-main.c
This commit is contained in:
John Reiser
2022-10-23 10:39:23 -07:00
committed by Markus F.X.J. Oberhumer
parent afeaeeddec
commit c331b9f1e2
1 changed files with 17 additions and 8 deletions
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25
src/stub/src/amd64-linux.elf-main.c
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@ -415,6 +415,7 @@ xfind_pages(unsigned mflags, Elf64_Phdr const *phdr, int phnum,
mflags += MAP_PRIVATE | MAP_ANONYMOUS; // '+' can optimize better than '|'
DPRINTF("xfind_pages %%x %%p %%d %%p %%p\\n", mflags, phdr, phnum, elfaddr, p_brk);
for (; --phnum>=0; ++phdr) if (PT_LOAD==phdr->p_type) {
DPRINTF(" p_vaddr=%%p p_memsz=%%p\\n", phdr->p_vaddr, phdr->p_memsz);
if (phdr->p_vaddr < lo) {
lo = phdr->p_vaddr;
}
@ -477,6 +478,7 @@ do_xmap(
}
}
else { // PT_INTERP
DPRINTF("INTERP\\n", 0);
reloc = xfind_pages(
((ET_DYN!=ehdr->e_type) ? MAP_FIXED : 0), phdr, ehdr->e_phnum, &v_brk, *p_reloc
#if defined(__powerpc64__) || defined(__aarch64__)
@ -491,6 +493,8 @@ do_xmap(
auxv_up(av, AT_PHDR, phdr->p_vaddr + reloc);
} else
if (PT_LOAD==phdr->p_type) {
DPRINTF("LOAD p_offset=%%p p_vaddr=%%p p_filesz=%%p p_memsz=%%p p_flags=%%x\\n",
phdr->p_offset, phdr->p_vaddr, phdr->p_filesz, phdr->p_memsz, phdr->p_flags);
if (xi && !phdr->p_offset /*&& ET_EXEC==ehdr->e_type*/) { // 1st PT_LOAD
// ? Compressed PT_INTERP must not overwrite values from compressed a.out?
auxv_up(av, AT_PHDR, phdr->p_vaddr + reloc + ehdr->e_phoff);
@ -503,17 +507,22 @@ do_xmap(
size_t mlen = xo.size = phdr->p_filesz;
char *addr = xo.buf = reloc + (char *)phdr->p_vaddr;
char *haddr = phdr->p_memsz + addr;
size_t frag = (size_t)addr &~ PAGE_MASK;
mlen += frag;
addr -= frag;
unsigned lo_frag = (unsigned)(long)addr &~ PAGE_MASK;
unsigned hi_frag = -(lo_frag + mlen) &~ PAGE_MASK; // distance to next page
mlen += lo_frag;
addr -= lo_frag;
#if defined(__powerpc64__) || defined(__aarch64__)
// Round up to hardware PAGE_SIZE; allows emulator with smaller.
// But (later) still need bzero when .p_filesz < .p_memsz .
mlen += -(mlen + (size_t)addr) &~ PAGE_MASK;
DPRINTF(" mlen=%%p\\n", mlen);
#endif
DPRINTF("mmap addr=%%p len=%%p offset=%%p lo_frag=%%p\\n",
addr, mlen, phdr->p_offset - lo_frag, lo_frag);
if (addr != mmap(addr, mlen, prot | (xi ? PROT_WRITE : 0),
MAP_FIXED | MAP_PRIVATE | (xi ? MAP_ANONYMOUS : 0),
(xi ? -1 : fdi), phdr->p_offset - frag) ) {
(xi ? -1 : fdi), phdr->p_offset - lo_frag) ) {
err_exit(8);
}
if (xi) {
@ -521,11 +530,10 @@ do_xmap(
}
// Linux does not fixup the low end, so neither do we.
//if (PROT_WRITE & prot) {
// bzero(addr, frag); // fragment at lo end
// bzero(addr, lo_frag); // fragment at lo end
//}
frag = (-mlen) &~ PAGE_MASK; // distance to next page boundary
if (PROT_WRITE & prot) { // note: read-only .bss not supported here
bzero(mlen+addr, frag); // fragment at hi end
bzero(phdr->p_filesz + lo_frag + addr, hi_frag);
}
if (xi) {
#if defined(__x86_64) //{
@ -543,8 +551,9 @@ do_xmap(
ERR_LAB
}
}
addr += mlen + frag; /* page boundary on hi end */
addr += mlen + hi_frag; /* page boundary on hi end */
if (addr < haddr) { // need pages for .bss
DPRINTF("zmap addr=%%p len=%%p\\n", addr, haddr - addr);
if (addr != mmap(addr, haddr - addr, prot,
MAP_FIXED | MAP_PRIVATE | MAP_ANONYMOUS, -1, 0 ) ) {
err_exit(9);