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: Iea3dcd44d0f4f61de3288ed1e26d8bd5e39115d2
diff --git a/drm/mediadrm/plugins/clearkey/hidl/CryptoPlugin.cpp b/drm/mediadrm/plugins/clearkey/hidl/CryptoPlugin.cpp
index 1495703..d278633 100644
--- a/drm/mediadrm/plugins/clearkey/hidl/CryptoPlugin.cpp
+++ b/drm/mediadrm/plugins/clearkey/hidl/CryptoPlugin.cpp
@@ -119,7 +119,11 @@
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_V1_2::ERROR_DRM_CANNOT_HANDLE, 0, "invalid buffer size");
return Void();
}