Commit 49ee4dd2 authored by Petr Mladek's avatar Petr Mladek
Browse files

livepatch: Proper error handling in the shadow variables selftest 



Add proper error handling when allocating or getting shadow variables
in the selftest. It prevents an invalid pointer access in some situations.
It shows the good programming practice in the others.

The error codes are just the best guess and specific for this particular
test. In general, klp_shadow_alloc() returns NULL also when the given
shadow variable has already been allocated. In addition, both
klp_shadow_alloc() and klp_shadow_get_or_alloc() might fail from
other reasons when the constructor fails.

Note, that the error code is not really important even in the real life.
The use of shadow variables should be transparent for the original
livepatched code.

Acked-by: default avatarMiroslav Benes <mbenes@suse.cz>
Acked-by: default avatarJoe Lawrence <joe.lawrence@redhat.com>
Signed-off-by: default avatarPetr Mladek <pmladek@suse.com>
parent 86e43f23

lib/livepatch/test_klp_shadow_vars.c

+22 −0
Original line number Original line Diff line number Diff line
@@ -154,22 +154,37 @@ static int test_klp_shadow_vars_init(void) 
	 * Allocate a few shadow variables with different <obj> and <id>.

	 * Allocate a few shadow variables with different <obj> and <id>.

	 */

	 */

	sv1 = shadow_alloc(obj, id, size, gfp_flags, shadow_ctor, &var1);

	sv1 = shadow_alloc(obj, id, size, gfp_flags, shadow_ctor, &var1);

	if (!sv1)

		return -ENOMEM;



	sv2 = shadow_alloc(obj + 1, id, size, gfp_flags, shadow_ctor, &var2);

	sv2 = shadow_alloc(obj + 1, id, size, gfp_flags, shadow_ctor, &var2);

	if (!sv2)

		return -ENOMEM;



	sv3 = shadow_alloc(obj, id + 1, size, gfp_flags, shadow_ctor, &var3);

	sv3 = shadow_alloc(obj, id + 1, size, gfp_flags, shadow_ctor, &var3);

	if (!sv3)

		return -ENOMEM;





	/*

	/*

	 * Verify we can find our new shadow variables and that they point

	 * Verify we can find our new shadow variables and that they point

	 * to expected data.

	 * to expected data.

	 */

	 */

	ret = shadow_get(obj, id);

	ret = shadow_get(obj, id);

	if (!ret)

		return -EINVAL;

	if (ret == sv1 && *sv1 == &var1)

	if (ret == sv1 && *sv1 == &var1)

		pr_info("  got expected PTR%d -> PTR%d result\n",

		pr_info("  got expected PTR%d -> PTR%d result\n",

			ptr_id(sv1), ptr_id(*sv1));

			ptr_id(sv1), ptr_id(*sv1));



	ret = shadow_get(obj + 1, id);

	ret = shadow_get(obj + 1, id);

	if (!ret)

		return -EINVAL;

	if (ret == sv2 && *sv2 == &var2)

	if (ret == sv2 && *sv2 == &var2)

		pr_info("  got expected PTR%d -> PTR%d result\n",

		pr_info("  got expected PTR%d -> PTR%d result\n",

			ptr_id(sv2), ptr_id(*sv2));

			ptr_id(sv2), ptr_id(*sv2));

	ret = shadow_get(obj, id + 1);

	ret = shadow_get(obj, id + 1);

	if (!ret)

		return -EINVAL;

	if (ret == sv3 && *sv3 == &var3)

	if (ret == sv3 && *sv3 == &var3)

		pr_info("  got expected PTR%d -> PTR%d result\n",

		pr_info("  got expected PTR%d -> PTR%d result\n",

			ptr_id(sv3), ptr_id(*sv3));

			ptr_id(sv3), ptr_id(*sv3));
@@ -179,7 +194,12 @@ static int test_klp_shadow_vars_init(void) 
	 * The second invocation should return the same shadow var.

	 * The second invocation should return the same shadow var.

	 */

	 */

	sv4 = shadow_get_or_alloc(obj + 2, id, size, gfp_flags, shadow_ctor, &var4);

	sv4 = shadow_get_or_alloc(obj + 2, id, size, gfp_flags, shadow_ctor, &var4);

	if (!sv4)

		return -ENOMEM;



	ret = shadow_get_or_alloc(obj + 2, id, size, gfp_flags, shadow_ctor, &var4);

	ret = shadow_get_or_alloc(obj + 2, id, size, gfp_flags, shadow_ctor, &var4);

	if (!ret)

		return -EINVAL;

	if (ret == sv4 && *sv4 == &var4)

	if (ret == sv4 && *sv4 == &var4)

		pr_info("  got expected PTR%d -> PTR%d result\n",

		pr_info("  got expected PTR%d -> PTR%d result\n",

			ptr_id(sv4), ptr_id(*sv4));

			ptr_id(sv4), ptr_id(*sv4));
@@ -207,6 +227,8 @@ static int test_klp_shadow_vars_init(void) 
	 * We should still find an <id+1> variable.

	 * We should still find an <id+1> variable.

	 */

	 */

	ret = shadow_get(obj, id + 1);

	ret = shadow_get(obj, id + 1);

	if (!ret)

		return -EINVAL;

	if (ret == sv3 && *sv3 == &var3)

	if (ret == sv3 && *sv3 == &var3)

		pr_info("  got expected PTR%d -> PTR%d result\n",

		pr_info("  got expected PTR%d -> PTR%d result\n",

			ptr_id(sv3), ptr_id(*sv3));

			ptr_id(sv3), ptr_id(*sv3));

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