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Mach-o defend against bad crafted input

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https://github.com/upx/upx/issues/146
	modified:   p_mach.cpp
This commit is contained in:
John Reiser 2017-11-15 13:38:54 -08:00
parent 7a0514d9b4
commit 6eafa552bb
1 changed files with 15 additions and 3 deletions
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18
src/p_mach.cpp
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@ -1562,7 +1562,7 @@ void PackMachBase<T>::unpack(OutputFile *fo)
for (unsigned j= 0; j < ncmds; ++j) {
memcpy(&msegcmd[j], ptr, umin(sizeof(Mach_segment_command),
((Mach_command const *)ptr)->cmdsize));
ptr += (unsigned) ((Mach_segment_command const *)ptr)->cmdsize;
ptr += (unsigned) ((Mach_command const *)ptr)->cmdsize;
if (ptr_udiff(ptr, mhdr) > ph.u_len) {
throwCantUnpack("cmdsize");
}
@ -1840,6 +1840,11 @@ bool PackMachBase<T>::canPack()
my_cpusubtype = mhdri.cpusubtype;
unsigned const sz_mhcmds = (unsigned)mhdri.sizeofcmds;
unsigned headway = file_size - sizeof(mhdri);
if (headway < sz_mhcmds) {
char buf[32]; snprintf(buf, sizeof(buf), "bad sizeofcmds %d", sz_mhcmds);
throwCantPack(buf);
}
if (16384 < sz_mhcmds) { // somewhat arbitrary, but amd64-darwin.macho-upxmain.c
throwCantPack("16384 < Mach_header.sizeofcmds");
}
@ -1854,6 +1859,13 @@ bool PackMachBase<T>::canPack()
unsigned char const *ptr = (unsigned char const *)rawmseg;
for (unsigned j= 0; j < ncmds; ++j) {
Mach_segment_command const *segptr = (Mach_segment_command const *)ptr;
if (headway < ((Mach_command const *)ptr)->cmdsize) {
char buf[64]; snprintf(buf, sizeof(buf),
"bad Mach_command[%d]{%#x, %#x}", j,
(unsigned)segptr->cmd, (unsigned)((Mach_command const *)ptr)->cmdsize);
throwCantPack(buf);
}
headway -= ((Mach_command const *)ptr)->cmdsize;
if (lc_seg == segptr->cmd) {
msegcmd[j] = *segptr;
if (!strcmp("__DATA", segptr->segname)) {
@ -1871,7 +1883,7 @@ bool PackMachBase<T>::canPack()
}
}
else {
memcpy(&msegcmd[j], ptr, 2*sizeof(unsigned)); // cmd and size
memcpy(&msegcmd[j], ptr, 2*sizeof(unsigned)); // cmd and cmdsize
}
switch (((Mach_uuid_command const *)ptr)->cmd) {
default: break;
@ -1891,7 +1903,7 @@ bool PackMachBase<T>::canPack()
memcpy(&cmdSRCVER, ptr, sizeof(cmdSRCVER));
} break;
}
ptr += (unsigned) ((const Mach_segment_command *)ptr)->cmdsize;
ptr += (unsigned) ((Mach_command const *)ptr)->cmdsize;
}
if (Mach_header::MH_DYLIB==my_filetype && 0==o__mod_init_func) {
infoWarning("missing -init function");