bpf: mark a NULL kfunc argument precisegrafted

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>

1 files changed, 20 insertions, 0 deletions

diff --git a/fs/befs/datastream.h b/fs/befs/datastream.h
new file mode 100644
index 000000000..39b1d4766
--- /dev/null
+++ b/fs/befs/datastream.h
@@ -0,0 +1,20 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * datastream.h
+ *
+ */
+
+struct buffer_head *befs_read_datastream(struct super_block *sb,
+					 const befs_data_stream *ds,
+					 befs_off_t pos, uint *off);
+
+int befs_fblock2brun(struct super_block *sb, const befs_data_stream *data,
+		     befs_blocknr_t fblock, befs_block_run *run);
+
+size_t befs_read_lsymlink(struct super_block *sb, const befs_data_stream *data,
+			  void *buff, befs_off_t len);
+
+befs_blocknr_t befs_count_blocks(struct super_block *sb,
+			  const befs_data_stream *ds);
+
+extern const befs_inode_addr BAD_IADDR;