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, 49 insertions, 0 deletions

diff --git a/Documentation/crypto/libcrypto-unauth-encryption.rst b/Documentation/crypto/libcrypto-unauth-encryption.rst
new file mode 100644
index 000000000..b4639b892
--- /dev/null
+++ b/Documentation/crypto/libcrypto-unauth-encryption.rst
@@ -0,0 +1,49 @@
+.. SPDX-License-Identifier: GPL-2.0-or-later
+
+Unauthenticated encryption
+==========================
+
+These APIs provide support for unauthenticated encryption and decryption,
+including bare stream ciphers and other length-preserving algorithms such as
+block ciphers in XTS mode.  The legitimate use cases for these algorithms are:
+
+- Support for legacy protocols that really should have chosen an authenticated
+  mode (or even another primitive entirely) but didn't.
+
+- Internal components of authenticated modes.  For example, AES-CTR is used by
+  AES-GCM and AES-CCM internally.
+
+- Storage encryption that cannot accommodate ciphertext expansion.  Usually
+  AES-XTS is used for this.
+
+- Stream ciphers for key derivation and random number generation.
+
+Besides the above, these shouldn't be used.
+
+AES-CBC and AES-CBC-CTS
+-----------------------
+
+This API provides support for AES in the CBC and CBC-CTS modes of operation.
+
+.. kernel-doc:: include/crypto/aes-cbc.h
+
+AES-CTR and AES-XCTR
+--------------------
+
+This API provides support for AES in the CTR and XCTR modes of operation.
+
+.. kernel-doc:: include/crypto/aes-ctr.h
+
+AES-ECB
+-------
+
+This API provides support for AES in the ECB mode of operation.
+
+.. kernel-doc:: include/crypto/aes-ecb.h
+
+AES-XTS
+-------
+
+This API provides support for AES in the XTS mode of operation.
+
+.. kernel-doc:: include/crypto/aes-xts.h