selftests/bpf: Reject graph kptr use after RCU unlockgrafted

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 <memxor@gmail.com>
Link: https://lore.kernel.org/r/20260904084325.52250-7-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

1 files changed, 43 insertions, 0 deletions

diff --git a/drivers/char/Makefile b/drivers/char/Makefile
new file mode 100644
index 000000000..a46d7bf7c
--- /dev/null
+++ b/drivers/char/Makefile
@@ -0,0 +1,43 @@
+# SPDX-License-Identifier: GPL-2.0
+#
+# Makefile for the kernel character device drivers.
+#
+
+obj-y				+= mem.o random.o
+obj-$(CONFIG_TTY_PRINTK)	+= ttyprintk.o
+obj-y				+= misc.o
+obj-$(CONFIG_TEST_MISC_MINOR)	+= misc_minor_kunit.o
+obj-$(CONFIG_ATARI_DSP56K)	+= dsp56k.o
+obj-$(CONFIG_VIRTIO_CONSOLE)	+= virtio_console.o
+obj-$(CONFIG_UV_MMTIMER)	+= uv_mmtimer.o
+obj-$(CONFIG_IBM_BSR)		+= bsr.o
+
+obj-$(CONFIG_PRINTER)		+= lp.o
+
+obj-$(CONFIG_APM_EMULATION)	+= apm-emulation.o
+
+obj-$(CONFIG_SONYPI)		+= sonypi.o
+obj-$(CONFIG_HPET)		+= hpet.o
+obj-$(CONFIG_XILINX_HWICAP)	+= xilinx_hwicap/
+obj-$(CONFIG_NVRAM)		+= nvram.o
+obj-$(CONFIG_TOSHIBA)		+= toshiba.o
+obj-$(CONFIG_DS1620)		+= ds1620.o
+obj-$(CONFIG_HW_RANDOM)		+= hw_random/
+obj-$(CONFIG_PPDEV)		+= ppdev.o
+obj-$(CONFIG_NWBUTTON)		+= nwbutton.o
+obj-$(CONFIG_NWFLASH)		+= nwflash.o
+obj-$(CONFIG_SCx200_GPIO)	+= scx200_gpio.o
+obj-$(CONFIG_PC8736x_GPIO)	+= pc8736x_gpio.o
+obj-$(CONFIG_NSC_GPIO)		+= nsc_gpio.o
+obj-$(CONFIG_TELCLOCK)		+= tlclk.o
+
+obj-y				+= agp/
+
+obj-$(CONFIG_HANGCHECK_TIMER)	+= hangcheck-timer.o
+obj-$(CONFIG_TCG_TPM)		+= tpm/
+
+obj-$(CONFIG_PS3_FLASH)		+= ps3flash.o
+
+obj-$(CONFIG_XILLYBUS_CLASS)	+= xillybus/
+obj-$(CONFIG_POWERNV_OP_PANEL)	+= powernv-op-panel.o
+obj-$(CONFIG_ADI)		+= adi.o