From c9b5693c7f024a6b0c7fc59123dbc313ecbf6e9b Mon Sep 17 00:00:00 2001 From: Edwin Wong Date: Tue, 26 Jan 2021 20:29:25 -0800 Subject: [PATCH] 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 --- drm/1.0/default/CryptoPlugin.cpp | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/drm/1.0/default/CryptoPlugin.cpp b/drm/1.0/default/CryptoPlugin.cpp index 19666f53a8..e60ba8f54d 100644 --- a/drm/1.0/default/CryptoPlugin.cpp +++ b/drm/1.0/default/CryptoPlugin.cpp @@ -125,7 +125,11 @@ 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(); }