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SubjectRe: [PATCH v2 3/4] livepatch: Proper error handling in the shadow variables selftest
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On 2/4/19 8:56 AM, Petr Mladek wrote:
> 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.
>
> Signed-off-by: Petr Mladek <pmladek@suse.com>
> ---
> lib/livepatch/test_klp_shadow_vars.c | 22 ++++++++++++++++++++++
> 1 file changed, 22 insertions(+)
>
> diff --git a/lib/livepatch/test_klp_shadow_vars.c b/lib/livepatch/test_klp_shadow_vars.c
> index f5441c193166..fe5c413efe96 100644
> --- a/lib/livepatch/test_klp_shadow_vars.c
> +++ b/lib/livepatch/test_klp_shadow_vars.c
> @@ -154,22 +154,37 @@ static int test_klp_shadow_vars_init(void)
> * Allocate a few shadow variables with different <obj> and <id>.
> */
> 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);
> + if (!sv2)
> + return -ENOMEM;
> +
> 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
> * to expected data.
> */
> ret = shadow_get(obj, id);
> + if (!ret)
> + return -EINVAL;
> if (ret == sv1 && *sv1 == &var1)
> pr_info(" got expected PTR%d -> PTR%d result\n",
> ptr_id(sv1), ptr_id(*sv1));
> +
> ret = shadow_get(obj + 1, id);
> + if (!ret)
> + return -EINVAL;
> if (ret == sv2 && *sv2 == &var2)
> pr_info(" got expected PTR%d -> PTR%d result\n",
> ptr_id(sv2), ptr_id(*sv2));
> ret = shadow_get(obj, id + 1);
> + if (!ret)
> + return -EINVAL;
> if (ret == sv3 && *sv3 == &var3)
> pr_info(" got expected PTR%d -> PTR%d result\n",
> 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.
> */
> 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);
> + if (!ret)
> + return -EINVAL;
> if (ret == sv4 && *sv4 == &var4)
> pr_info(" got expected PTR%d -> PTR%d result\n",
> 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.
> */
> ret = shadow_get(obj, id + 1);
> + if (!ret)
> + return -EINVAL;
> if (ret == sv3 && *sv3 == &var3)
> pr_info(" got expected PTR%d -> PTR%d result\n",
> ptr_id(sv3), ptr_id(*sv3));
>

Fixes look good to me,

Acked-by: Joe Lawrence <joe.lawrence@redhat.com>

-- Joe

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