+/*
+ * Validate the fat_header and fat_arch array in memory. We check that:
+ *
+ * 1) arch count would not exceed the data buffer
+ * 2) arch list does not contain duplicate cputype/cpusubtype tuples
+ * 3) arch list does not have two overlapping slices. The area
+ * at the front of the file containing the fat headers is implicitly
+ * a range that a slice should also not try to cover
+ */
+load_return_t
+fatfile_validate_fatarches(vm_offset_t data_ptr, vm_size_t data_size)
+{
+ uint32_t magic, nfat_arch;
+ uint32_t max_nfat_arch, i, j;
+ uint32_t fat_header_size;
+
+ struct fat_arch *arches;
+ struct fat_header *header;
+
+ if (sizeof(struct fat_header) > data_size) {
+ return (LOAD_FAILURE);
+ }
+
+ header = (struct fat_header *)data_ptr;
+ magic = OSSwapBigToHostInt32(header->magic);
+ nfat_arch = OSSwapBigToHostInt32(header->nfat_arch);
+
+ if (magic != FAT_MAGIC) {
+ /* must be FAT_MAGIC big endian */
+ return (LOAD_FAILURE);
+ }
+
+ max_nfat_arch = (data_size - sizeof(struct fat_header)) / sizeof(struct fat_arch);
+ if (nfat_arch > max_nfat_arch) {
+ /* nfat_arch would cause us to read off end of buffer */
+ return (LOAD_BADMACHO);
+ }
+
+ /* now that we know the fat_arch list fits in the buffer, how much does it use? */
+ fat_header_size = sizeof(struct fat_header) + nfat_arch * sizeof(struct fat_arch);
+ arches = (struct fat_arch *)(data_ptr + sizeof(struct fat_header));
+
+ for (i=0; i < nfat_arch; i++) {
+ uint32_t i_begin = OSSwapBigToHostInt32(arches[i].offset);
+ uint32_t i_size = OSSwapBigToHostInt32(arches[i].size);
+ uint32_t i_cputype = OSSwapBigToHostInt32(arches[i].cputype);
+ uint32_t i_cpusubtype = OSSwapBigToHostInt32(arches[i].cpusubtype);
+
+ if (i_begin < fat_header_size) {
+ /* slice is trying to claim part of the file used by fat headers themselves */
+ return (LOAD_BADMACHO);
+ }
+
+ if ((UINT32_MAX - i_size) < i_begin) {
+ /* start + size would overflow */
+ return (LOAD_BADMACHO);
+ }
+ uint32_t i_end = i_begin + i_size;
+
+ for (j=i+1; j < nfat_arch; j++) {
+ uint32_t j_begin = OSSwapBigToHostInt32(arches[j].offset);
+ uint32_t j_size = OSSwapBigToHostInt32(arches[j].size);
+ uint32_t j_cputype = OSSwapBigToHostInt32(arches[j].cputype);
+ uint32_t j_cpusubtype = OSSwapBigToHostInt32(arches[j].cpusubtype);
+
+ if ((i_cputype == j_cputype) && (i_cpusubtype == j_cpusubtype)) {
+ /* duplicate cputype/cpusubtype, results in ambiguous references */
+ return (LOAD_BADMACHO);
+ }
+
+ if ((UINT32_MAX - j_size) < j_begin) {
+ /* start + size would overflow */
+ return (LOAD_BADMACHO);
+ }
+ uint32_t j_end = j_begin + j_size;
+
+ if (i_begin <= j_begin) {
+ if (i_end <= j_begin) {
+ /* I completely precedes J */
+ } else {
+ /* I started before J, but ends somewhere in or after J */
+ return (LOAD_BADMACHO);
+ }
+ } else {
+ if (i_begin >= j_end) {
+ /* I started after J started but also after J ended */
+ } else {
+ /* I started after J started but before it ended, so there is overlap */
+ return (LOAD_BADMACHO);
+ }
+ }
+ }
+ }
+
+ return (LOAD_SUCCESS);
+}
projects / apple / xnu.git / blobdiff