Fix potential decrypt src pointer overflow.

There is a potential integer overflow to bypass the
source base size check in decrypt. The source pointer
can then point to the outside of the source buffer,
which could potentially leak arbitrary memory content
to destination pointer.

Test: sts-tradefed
  sts-tradefed run sts-engbuild-no-spl-lock -m StsHostTestCases --test android.security.sts.Bug_176496160#testPocBug_176496160

Test: push to device with target_hwasan-userdebug build
  adb shell /data/local/tmp/Bug-17649616064

Bug: 176496160
Bug: 176444786
Change-Id: I811a6f60948bde2a72906c2c6172fd7bc5feb6d9
This commit is contained in:
Edwin Wong
2021-01-26 20:29:25 -08:00
parent d1a977b771
commit c14f262876

View File

@@ -124,7 +124,11 @@ namespace implementation {
return Void();
}
if (source.offset + offset + source.size > sourceBase->getSize()) {
size_t totalSize = 0;
if (__builtin_add_overflow(source.offset, offset, &totalSize) ||
__builtin_add_overflow(totalSize, source.size, &totalSize) ||
totalSize > sourceBase->getSize()) {
android_errorWriteLog(0x534e4554, "176496160");
_hidl_cb(Status::ERROR_DRM_CANNOT_HANDLE, 0, "invalid buffer size");
return Void();
}