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, 70 insertions, 0 deletions

diff --git a/fs/quota/Kconfig b/fs/quota/Kconfig
new file mode 100644
index 000000000..818083a36
--- /dev/null
+++ b/fs/quota/Kconfig
@@ -0,0 +1,70 @@
+# SPDX-License-Identifier: GPL-2.0-only
+#
+#  Quota configuration
+#
+
+config QUOTA
+	bool "Quota support"
+	select QUOTACTL
+	help
+	  If you say Y here, you will be able to set per user limits for disk
+	  usage (also called disk quotas). Currently, it works for the
+	  ext2, ext3, ext4, f2fs, jfs and ocfs2 file systems. Note that gfs2
+	  and xfs use their own quota system. Ext3 and ext4 also support
+	  journaled quotas for which you don't need to run quotacheck(8) after
+	  an unclean shutdown. For further details, read the Quota mini-HOWTO,
+	  available from <https://www.tldp.org/docs.html#howto>, or the
+	  documentation provided with the quota tools. Probably the quota
+	  support is only useful for multi user systems. If unsure, say N.
+
+config QUOTA_NETLINK_INTERFACE
+	bool "Report quota messages through netlink interface"
+	depends on QUOTACTL && NET
+	help
+	  If you say Y here, quota warnings (about exceeding softlimit, reaching
+	  hardlimit, etc.) will be reported through netlink interface. If unsure,
+	  say Y.
+
+config PRINT_QUOTA_WARNING
+	bool "Print quota warnings to console (OBSOLETE)"
+	depends on QUOTA && BROKEN
+	default y
+	help
+	  If you say Y here, quota warnings (about exceeding softlimit, reaching
+	  hardlimit, etc.) will be printed to the process' controlling terminal.
+	  Note that this behavior is currently deprecated and may go away in
+	  future. Please use notification via netlink socket instead.
+
+config QUOTA_DEBUG
+	bool "Additional quota sanity checks"
+	depends on QUOTA
+	default n
+	help
+	  If you say Y here, quota subsystem will perform some additional
+	  sanity checks of quota internal structures. If unsure, say N.
+
+# Generic support for tree structured quota files. Selected when needed.
+config QUOTA_TREE
+	 tristate
+
+config QFMT_V1
+	tristate "Old quota format support"
+	depends on QUOTA
+	help
+	  This quota format was (is) used by kernels earlier than 2.4.22. If
+	  you have quota working and you don't want to convert to new quota
+	  format say Y here.
+
+config QFMT_V2
+	tristate "Quota format vfsv0 and vfsv1 support"
+	depends on QUOTA
+	select QUOTA_TREE
+	help
+	  This config option enables kernel support for vfsv0 and vfsv1 quota
+	  formats. Both these formats support 32-bit UIDs/GIDs and vfsv1 format
+	  also supports 64-bit inode and block quota limits. If you need this
+	  functionality say Y here.
+
+config QUOTACTL
+	bool
+	default n