From a5c14b7afbacb0017da1a3526b5768696f682a9f Mon Sep 17 00:00:00 2001 From: Edwin Wong Date: Tue, 26 Jan 2021 20:32:24 -0800 Subject: [PATCH] [RESTRICT AUTOMERGE] Fix potential decrypt srcPtr overflow. Merged from http://go/wvgerrit/114903 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: I208e0d5d949e8ef003fcf7d6f129eab66b9b3656 --- libwvdrmengine/mediacrypto/src_hidl/WVCryptoPlugin.cpp | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/libwvdrmengine/mediacrypto/src_hidl/WVCryptoPlugin.cpp b/libwvdrmengine/mediacrypto/src_hidl/WVCryptoPlugin.cpp index 3cd7a265..61846c01 100644 --- a/libwvdrmengine/mediacrypto/src_hidl/WVCryptoPlugin.cpp +++ b/libwvdrmengine/mediacrypto/src_hidl/WVCryptoPlugin.cpp @@ -152,7 +152,11 @@ Return WVCryptoPlugin::decrypt( return Void(); } - if (source.offset + offset + source.size > sourceBase->getSize()) { + size_t totalSrcSize = 0; + if (__builtin_add_overflow(source.offset, offset, &totalSrcSize) || + __builtin_add_overflow(totalSrcSize, source.size, &totalSrcSize) || + totalSrcSize > sourceBase->getSize()) { + android_errorWriteLog(0x534e4554, "176496160"); _hidl_cb(Status::ERROR_DRM_CANNOT_HANDLE, 0, "invalid buffer size"); return Void(); }