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, 97 insertions, 0 deletions

diff --git a/crypto/lz4hc.c b/crypto/lz4hc.c
new file mode 100644
index 000000000..bb84f8a68
--- /dev/null
+++ b/crypto/lz4hc.c
@@ -0,0 +1,97 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Cryptographic API.
+ *
+ * Copyright (c) 2013 Chanho Min <chanho.min@lge.com>
+ */
+#include <crypto/internal/scompress.h>
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/vmalloc.h>
+#include <linux/lz4.h>
+
+static void *lz4hc_alloc_ctx(void)
+{
+	void *ctx;
+
+	ctx = vmalloc(LZ4HC_MEM_COMPRESS);
+	if (!ctx)
+		return ERR_PTR(-ENOMEM);
+
+	return ctx;
+}
+
+static void lz4hc_free_ctx(void *ctx)
+{
+	vfree(ctx);
+}
+
+static int __lz4hc_compress_crypto(const u8 *src, unsigned int slen,
+				   u8 *dst, unsigned int *dlen, void *ctx)
+{
+	int out_len = LZ4_compress_HC(src, dst, slen,
+		*dlen, LZ4HC_DEFAULT_CLEVEL, ctx);
+
+	if (!out_len)
+		return -EINVAL;
+
+	*dlen = out_len;
+	return 0;
+}
+
+static int lz4hc_scompress(struct crypto_scomp *tfm, const u8 *src,
+			   unsigned int slen, u8 *dst, unsigned int *dlen,
+			   void *ctx)
+{
+	return __lz4hc_compress_crypto(src, slen, dst, dlen, ctx);
+}
+
+static int __lz4hc_decompress_crypto(const u8 *src, unsigned int slen,
+				     u8 *dst, unsigned int *dlen, void *ctx)
+{
+	int out_len = LZ4_decompress_safe(src, dst, slen, *dlen);
+
+	if (out_len < 0)
+		return -EINVAL;
+
+	*dlen = out_len;
+	return 0;
+}
+
+static int lz4hc_sdecompress(struct crypto_scomp *tfm, const u8 *src,
+			     unsigned int slen, u8 *dst, unsigned int *dlen,
+			     void *ctx)
+{
+	return __lz4hc_decompress_crypto(src, slen, dst, dlen, NULL);
+}
+
+static struct scomp_alg scomp = {
+	.streams		= {
+		.alloc_ctx	= lz4hc_alloc_ctx,
+		.free_ctx	= lz4hc_free_ctx,
+	},
+	.compress		= lz4hc_scompress,
+	.decompress		= lz4hc_sdecompress,
+	.base			= {
+		.cra_name	= "lz4hc",
+		.cra_driver_name = "lz4hc-scomp",
+		.cra_module	 = THIS_MODULE,
+	}
+};
+
+static int __init lz4hc_mod_init(void)
+{
+	return crypto_register_scomp(&scomp);
+}
+
+static void __exit lz4hc_mod_fini(void)
+{
+	crypto_unregister_scomp(&scomp);
+}
+
+module_init(lz4hc_mod_init);
+module_exit(lz4hc_mod_fini);
+
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("LZ4HC Compression Algorithm");
+MODULE_ALIAS_CRYPTO("lz4hc");