From 75467f60a3d14f08f86f2b353298d2826382ff23 Mon Sep 17 00:00:00 2001
From: Linus Torvalds <torvalds@linux-foundation.org>
Date: Fri, 25 Sep 2026 15:55:03 -0700
Subject: Merge tag 'ipe-pr-20260925' of
 git://git.kernel.org/pub/scm/linux/kernel/git/wufan/ipe

Pull IPE fixes from Fan Wu:
 "Two fixes for use-after-free issues found by recent LLM-assisted code
  analysis.

   - move successful policy load auditing under the new policy
     directory's inode lock, preventing a concurrent policy deletion
     from freeing the policy while it is still being audited

   - protect the dm-verity root hash with RCU, preventing policy
     evaluation from racing with root hash replacement during preresume"

* tag 'ipe-pr-20260925' of git://git.kernel.org/pub/scm/linux/kernel/git/wufan/ipe:
  ipe: protect the dm-verity root hash with RCU
  ipe: fix use-after-free when auditing a newly loaded policy
---
 lib/crypto/arc4.c | 76 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 76 insertions(+)
 create mode 100644 lib/crypto/arc4.c

(limited to 'lib/crypto/arc4.c')

diff --git a/lib/crypto/arc4.c b/lib/crypto/arc4.c
new file mode 100644
index 000000000..4e950e1e6
--- /dev/null
+++ b/lib/crypto/arc4.c
@@ -0,0 +1,76 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Cryptographic API
+ *
+ * ARC4 Cipher Algorithm
+ *
+ * Jon Oberheide <jon@oberheide.org>
+ */
+
+#include <crypto/arc4.h>
+#include <linux/export.h>
+#include <linux/module.h>
+
+int arc4_setkey(struct arc4_ctx *ctx, const u8 *in_key, unsigned int key_len)
+{
+	int i, j = 0, k = 0;
+
+	ctx->x = 1;
+	ctx->y = 0;
+
+	for (i = 0; i < 256; i++)
+		ctx->S[i] = i;
+
+	for (i = 0; i < 256; i++) {
+		u32 a = ctx->S[i];
+
+		j = (j + in_key[k] + a) & 0xff;
+		ctx->S[i] = ctx->S[j];
+		ctx->S[j] = a;
+		if (++k >= key_len)
+			k = 0;
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL(arc4_setkey);
+
+void arc4_crypt(struct arc4_ctx *ctx, u8 *out, const u8 *in, unsigned int len)
+{
+	u32 *const S = ctx->S;
+	u32 x, y, a, b;
+	u32 ty, ta, tb;
+
+	if (len == 0)
+		return;
+
+	x = ctx->x;
+	y = ctx->y;
+
+	a = S[x];
+	y = (y + a) & 0xff;
+	b = S[y];
+
+	do {
+		S[y] = a;
+		a = (a + b) & 0xff;
+		S[x] = b;
+		x = (x + 1) & 0xff;
+		ta = S[x];
+		ty = (y + ta) & 0xff;
+		tb = S[ty];
+		*out++ = *in++ ^ S[a];
+		if (--len == 0)
+			break;
+		y = ty;
+		a = ta;
+		b = tb;
+	} while (true);
+
+	ctx->x = x;
+	ctx->y = y;
+}
+EXPORT_SYMBOL(arc4_crypt);
+
+MODULE_DESCRIPTION("ARC4 Cipher Algorithm");
+MODULE_LICENSE("GPL");
-- 
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