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, 110 insertions, 0 deletions

diff --git a/fs/jffs2/compr_lzo.c b/fs/jffs2/compr_lzo.c
new file mode 100644
index 000000000..c553bd650
--- /dev/null
+++ b/fs/jffs2/compr_lzo.c
@@ -0,0 +1,110 @@
+/*
+ * JFFS2 -- Journalling Flash File System, Version 2.
+ *
+ * Copyright © 2007 Nokia Corporation. All rights reserved.
+ * Copyright © 2004-2010 David Woodhouse <dwmw2@infradead.org>
+ *
+ * Created by Richard Purdie <rpurdie@openedhand.com>
+ *
+ * For licensing information, see the file 'LICENCE' in this directory.
+ *
+ */
+
+#include <linux/kernel.h>
+#include <linux/sched.h>
+#include <linux/vmalloc.h>
+#include <linux/init.h>
+#include <linux/lzo.h>
+#include "compr.h"
+
+static void *lzo_mem;
+static void *lzo_compress_buf;
+static DEFINE_MUTEX(deflate_mutex);	/* for lzo_mem and lzo_compress_buf */
+
+static void free_workspace(void)
+{
+	vfree(lzo_mem);
+	vfree(lzo_compress_buf);
+}
+
+static int __init alloc_workspace(void)
+{
+	lzo_mem = vmalloc(LZO1X_MEM_COMPRESS);
+	lzo_compress_buf = vmalloc(lzo1x_worst_compress(PAGE_SIZE));
+
+	if (!lzo_mem || !lzo_compress_buf) {
+		free_workspace();
+		return -ENOMEM;
+	}
+
+	return 0;
+}
+
+static int jffs2_lzo_compress(unsigned char *data_in, unsigned char *cpage_out,
+			      uint32_t *sourcelen, uint32_t *dstlen)
+{
+	size_t compress_size;
+	int ret;
+
+	mutex_lock(&deflate_mutex);
+	ret = lzo1x_1_compress(data_in, *sourcelen, lzo_compress_buf, &compress_size, lzo_mem);
+	if (ret != LZO_E_OK)
+		goto fail;
+
+	if (compress_size > *dstlen)
+		goto fail;
+
+	memcpy(cpage_out, lzo_compress_buf, compress_size);
+	mutex_unlock(&deflate_mutex);
+
+	*dstlen = compress_size;
+	return 0;
+
+ fail:
+	mutex_unlock(&deflate_mutex);
+	return -1;
+}
+
+static int jffs2_lzo_decompress(unsigned char *data_in, unsigned char *cpage_out,
+				 uint32_t srclen, uint32_t destlen)
+{
+	size_t dl = destlen;
+	int ret;
+
+	ret = lzo1x_decompress_safe(data_in, srclen, cpage_out, &dl);
+
+	if (ret != LZO_E_OK || dl != destlen)
+		return -1;
+
+	return 0;
+}
+
+static struct jffs2_compressor jffs2_lzo_comp = {
+	.priority = JFFS2_LZO_PRIORITY,
+	.name = "lzo",
+	.compr = JFFS2_COMPR_LZO,
+	.compress = &jffs2_lzo_compress,
+	.decompress = &jffs2_lzo_decompress,
+	.disabled = 0,
+};
+
+int __init jffs2_lzo_init(void)
+{
+	int ret;
+
+	ret = alloc_workspace();
+	if (ret < 0)
+		return ret;
+
+	ret = jffs2_register_compressor(&jffs2_lzo_comp);
+	if (ret)
+		free_workspace();
+
+	return ret;
+}
+
+void jffs2_lzo_exit(void)
+{
+	jffs2_unregister_compressor(&jffs2_lzo_comp);
+	free_workspace();
+}