From 506ada89629ec7059b96ecfb0dc7d33ece0103ca Mon Sep 17 00:00:00 2001
From: Eduard Zingerman <eddyz87@gmail.com>
Date: Fri, 4 Sep 2026 17:05:56 -0700
Subject: bpf: mark a NULL kfunc argument precise

check_kfunc_arg() allows bpf_register_is_null() for nullable arguments
w/o marking the underlying scalar register precise. Hence a checkpoint
created on such a path would prune against arbitrary scalar value.

Fixes: 3bda08b63670 ("bpf: Allow NULL buffers in bpf_dynptr_slice(_rw)")
Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20260904-register-is-null-precise-fixes-v1-5-0f5a360ff15d@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
---
 fs/befs/io.c | 61 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 61 insertions(+)
 create mode 100644 fs/befs/io.c

(limited to 'fs/befs/io.c')

diff --git a/fs/befs/io.c b/fs/befs/io.c
new file mode 100644
index 000000000..2caf50a4a
--- /dev/null
+++ b/fs/befs/io.c
@@ -0,0 +1,61 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * linux/fs/befs/io.c
+ *
+ * Copyright (C) 2001 Will Dyson <will_dyson@pobox.com
+ *
+ * Based on portions of file.c and inode.c
+ * by Makoto Kato (m_kato@ga2.so-net.ne.jp)
+ *
+ * Many thanks to Dominic Giampaolo, author of Practical File System
+ * Design with the Be File System, for such a helpful book.
+ *
+ */
+
+#include <linux/buffer_head.h>
+
+#include "befs.h"
+#include "io.h"
+
+/*
+ * Converts befs notion of disk addr to a disk offset and uses
+ * linux kernel function sb_bread() to get the buffer containing
+ * the offset.
+ */
+
+struct buffer_head *
+befs_bread_iaddr(struct super_block *sb, befs_inode_addr iaddr)
+{
+	struct buffer_head *bh;
+	befs_blocknr_t block;
+	struct befs_sb_info *befs_sb = BEFS_SB(sb);
+
+	befs_debug(sb, "---> Enter %s "
+		   "[%u, %hu, %hu]", __func__, iaddr.allocation_group,
+		   iaddr.start, iaddr.len);
+
+	if (iaddr.allocation_group > befs_sb->num_ags) {
+		befs_error(sb, "BEFS: Invalid allocation group %u, max is %u",
+			   iaddr.allocation_group, befs_sb->num_ags);
+		goto error;
+	}
+
+	block = iaddr2blockno(sb, &iaddr);
+
+	befs_debug(sb, "%s: offset = %lu", __func__, (unsigned long)block);
+
+	bh = sb_bread(sb, block);
+
+	if (bh == NULL) {
+		befs_error(sb, "Failed to read block %lu",
+			   (unsigned long)block);
+		goto error;
+	}
+
+	befs_debug(sb, "<--- %s", __func__);
+	return bh;
+
+error:
+	befs_debug(sb, "<--- %s ERROR", __func__);
+	return NULL;
+}
-- 
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