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2023-12-08 01573e231f18eb2d99162747186f59511f56b64d

 kernel/samples/livepatch/livepatch-shadow-fix1.c
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@@ -1,18 +1,6 @@
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+// SPDX-License-Identifier: GPL-2.0-or-later
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 /*
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  * Copyright (C) 2017 Joe Lawrence <joe.lawrence@redhat.com>
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- *
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- * This program is free software; you can redistribute it and/or
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- * modify it under the terms of the GNU General Public License
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- * as published by the Free Software Foundation; either version 2
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- * of the License, or (at your option) any later version.
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- *
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- * This program is distributed in the hope that it will be useful,
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- * but WITHOUT ANY WARRANTY; without even the implied warranty of
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- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
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- * GNU General Public License for more details.
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- *
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- * You should have received a copy of the GNU General Public License
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- * along with this program; if not, see <http://www.gnu.org/licenses/>.
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  */
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5
 
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 /*
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@@ -64,17 +52,21 @@
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  */
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 static int shadow_leak_ctor(void *obj, void *shadow_data, void *ctor_data)
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 {
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-	void **shadow_leak = shadow_data;
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-	void *leak = ctor_data;
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+	int **shadow_leak = shadow_data;
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+	int **leak = ctor_data;
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-	*shadow_leak = leak;
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+	if (!ctor_data)
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+		return -EINVAL;
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+
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+	*shadow_leak = *leak;
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 	return 0;
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 }
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64
 
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-struct dummy *livepatch_fix1_dummy_alloc(void)
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+static struct dummy *livepatch_fix1_dummy_alloc(void)
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 {
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 	struct dummy *d;
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-	void *leak;
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+	int *leak;
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+	int **shadow_leak;
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 	d = kzalloc(sizeof(*d), GFP_KERNEL);
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 	if (!d)
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@@ -88,34 +80,43 @@
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 	 * variable.  A patched dummy_free routine can later fetch this
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 	 * pointer to handle resource release.
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 	 */
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-	leak = kzalloc(sizeof(int), GFP_KERNEL);
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-	if (!leak) {
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-		kfree(d);
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-		return NULL;
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-	}
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+	leak = kzalloc(sizeof(*leak), GFP_KERNEL);
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+	if (!leak)
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+		goto err_leak;
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-	klp_shadow_alloc(d, SV_LEAK, sizeof(leak), GFP_KERNEL,
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-			 shadow_leak_ctor, leak);
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+	shadow_leak = klp_shadow_alloc(d, SV_LEAK, sizeof(leak), GFP_KERNEL,
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+				       shadow_leak_ctor, &leak);
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+	if (!shadow_leak) {
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+		pr_err("%s: failed to allocate shadow variable for the leaking pointer: dummy @ %p, leak @ %p\n",
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+		       __func__, d, leak);
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+		goto err_shadow;
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+	}
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 	pr_info("%s: dummy @ %p, expires @ %lx\n",
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 		__func__, d, d->jiffies_expire);
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 	return d;
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+
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+err_shadow:
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+	kfree(leak);
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+err_leak:
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+	kfree(d);
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+	return NULL;
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 }
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 static void livepatch_fix1_dummy_leak_dtor(void *obj, void *shadow_data)
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 {
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 	void *d = obj;
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-	void **shadow_leak = shadow_data;
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+	int **shadow_leak = shadow_data;
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 	kfree(*shadow_leak);
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 	pr_info("%s: dummy @ %p, prevented leak @ %p\n",
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 			 __func__, d, *shadow_leak);
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 }
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-void livepatch_fix1_dummy_free(struct dummy *d)
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+static void livepatch_fix1_dummy_free(struct dummy *d)
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 {
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-	void **shadow_leak;
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+	int **shadow_leak;
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 	/*
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 	 * Patch: fetch the saved SV_LEAK shadow variable, detach and
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@@ -157,25 +158,13 @@
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 static int livepatch_shadow_fix1_init(void)
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 {
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-	int ret;
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-
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-	ret = klp_register_patch(&patch);
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-	if (ret)
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-		return ret;
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-	ret = klp_enable_patch(&patch);
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-	if (ret) {
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-		WARN_ON(klp_unregister_patch(&patch));
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-		return ret;
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-	}
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-	return 0;
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+	return klp_enable_patch(&patch);
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 }
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 static void livepatch_shadow_fix1_exit(void)
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 {
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 	/* Cleanup any existing SV_LEAK shadow variables */
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 	klp_shadow_free_all(SV_LEAK, livepatch_fix1_dummy_leak_dtor);
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-
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-	WARN_ON(klp_unregister_patch(&patch));
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 }
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 module_init(livepatch_shadow_fix1_init);