Add a build option for enabling undefined behavior sanitizer, use for CI

Similar to ASAN, now that we can this is a nice and cheap way to keep
compiler gremlins at bay.

CMakeLists.txt

@@ -19,6 +19,7 @@ option(ENABLE_NDB "Enable ndb rpmdb support" ON)
 option(ENABLE_BDB_RO "Enable read-only Berkeley DB rpmdb support (EXPERIMENTAL)" OFF)
 option(ENABLE_TESTSUITE "Enable test-suite" ON)
 option(ENABLE_ASAN "Enable address-sanitizer" OFF)
+option(ENABLE_UBSAN "Enable undefined behavior-sanitizer" OFF)
 
 option(WITH_CAP "Build with capability support" ON)
 option(WITH_ACL "Build with ACL support" ON)
@@ -376,10 +377,18 @@ endif()
 
 if (ENABLE_ASAN)
 	add_compile_options(-fsanitize=address)
-	add_compile_options(-fno-omit-frame-pointer)
 	add_link_options(-fsanitize=address)
 endif()
 
+if (ENABLE_UBSAN)
+	add_compile_options(-fsanitize=undefined)
+	add_link_options(-fsanitize=undefined)
+endif()
+
+if (ENABLE_ASAN OR ENABLE_UBSAN)
+	add_compile_options(-fno-omit-frame-pointer)
+endif()
+
 # try to ensure some compiler sanity
 foreach (flag -fno-strict-overflow -fno-delete-null-pointer-checks)
 	check_c_compiler_flag(${flag} found)

tests/Dockerfile.fedora

@@ -50,6 +50,7 @@ RUN dnf -y install \
   fsverity-utils fsverity-utils-devel \
   pandoc \
   libasan \
+  libubsan \
   && dnf clean all
 RUN echo "%_dbpath $(rpm --eval '%_dbpath')" > /root/.rpmmacros
 
@@ -79,6 +80,7 @@ ENV CFLAGS="-Og -g"
 RUN cmake \
 	-DENABLE_WERROR=ON \
 	-DENABLE_ASAN=ON \
+	-DENABLE_UBSAN=ON \
 	-DENABLE_BDB_RO=ON \
 	-DWITH_FSVERITY=ON \
 	-DWITH_IMAEVM=ON \