From 6668ed271eaefaa63e686bdfbedaeb7b8e492722 Mon Sep 17 00:00:00 2001 From: Kumar Kartikeya Dwivedi Date: Fri, 4 Sep 2026 10:43:19 +0200 Subject: selftests/bpf: Reject graph kptr use after RCU unlock Add a sleepable verifier test that loads a graph-node local kptr in an explicit RCU read-side critical section, then passes its node to bpf_rbtree_remove() after the section ends. Before the verifier fix, the stale NON_OWN_REF flag makes the node look like a live borrowed reference and the program is accepted. After the fix, the pointer is demoted without NON_OWN_REF and the graph kfunc argument is rejected. Also exercise a graph kptr loaded while a spin lock provides implicit RCU protection. The pointer must be invalidated when the lock is released, which guards the required ordering between non-owning-reference invalidation and RCU demotion. Update the existing fault-protected load test state description. The post-unlock pointer no longer carries NON_OWN_REF, but remains readable because the load is rewritten to use BPF_PROBE_MEM. Signed-off-by: Kumar Kartikeya Dwivedi Link: https://lore.kernel.org/r/20260904084325.52250-7-memxor@gmail.com Signed-off-by: Alexei Starovoitov --- tools/virtio/Makefile | 58 +++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 58 insertions(+) create mode 100644 tools/virtio/Makefile (limited to 'tools/virtio/Makefile') diff --git a/tools/virtio/Makefile b/tools/virtio/Makefile new file mode 100644 index 000000000..2cac5fd4b --- /dev/null +++ b/tools/virtio/Makefile @@ -0,0 +1,58 @@ +# SPDX-License-Identifier: GPL-2.0 +all: test mod +test: virtio_test vringh_test vhost_net_test +virtio_test: virtio_ring.o virtio_test.o +vringh_test: vringh_test.o vringh.o virtio_ring.o +vhost_net_test: virtio_ring.o vhost_net_test.o + +try-run = $(shell set -e; \ + if ($(1)) >/dev/null 2>&1; \ + then echo "$(2)"; \ + else echo "$(3)"; \ + fi) + +__cc-option = $(call try-run,\ + $(1) -Werror $(2) -c -x c /dev/null -o /dev/null,$(2),) +cc-option = $(call __cc-option, $(CC),$(1)) + +CFLAGS += -g -O2 -Werror -Wno-maybe-uninitialized -Wall -I. -I../include/ -I ../../usr/include/ -Wno-pointer-sign -fno-strict-overflow -fno-strict-aliasing -fno-common -MMD -U_FORTIFY_SOURCE -include ../../include/linux/kconfig.h $(call cc-option,-mfunction-return=thunk) $(call cc-option,-fcf-protection=none) $(call cc-option,-mindirect-branch-register) + +CFLAGS += -pthread +LDFLAGS += -pthread +vpath %.c ../../drivers/virtio ../../drivers/vhost +BUILD=KCFLAGS="-I "`pwd`/../../drivers/vhost ${MAKE} -C `pwd`/../.. V=${V} +mod: + ${BUILD} M=`pwd`/vhost_test + +#oot: build vhost as an out of tree module for a distro kernel +#no effort is taken to make it actually build or work, but tends to mostly work +#if the distro kernel is very close to upstream +#unsupported! this is a development tool only, don't use the +#resulting modules in production! +OOT_KSRC=/lib/modules/$$(uname -r)/build +OOT_VHOST=`pwd`/../../drivers/vhost +#Everyone depends on vhost +#Tweak the below to enable more modules +OOT_CONFIGS=\ + CONFIG_VHOST=m \ + CONFIG_VHOST_NET=n \ + CONFIG_VHOST_SCSI=n \ + CONFIG_VHOST_VSOCK=n \ + CONFIG_VHOST_RING=n \ + CONFIG_VHOST_VDPA=n +OOT_BUILD=KCFLAGS="-include "`pwd`"/oot-stubs.h -I "${OOT_VHOST} ${MAKE} -C ${OOT_KSRC} V=${V} +oot-build: + echo "UNSUPPORTED! Don't use the resulting modules in production!" + ${OOT_BUILD} M=`pwd`/vhost_test + ${OOT_BUILD} M=${OOT_VHOST} ${OOT_CONFIGS} + +oot-clean: oot-build +oot: oot-build +oot-clean: OOT_BUILD+=clean + +.PHONY: all test mod clean vhost oot oot-clean oot-build +clean: + ${RM} *.o vringh_test virtio_test vhost_net_test vhost_test/*.o \ + vhost_test/.*.cmd vhost_test/Module.symvers \ + vhost_test/modules.order *.d +-include *.d -- cgit v1.3.1