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![Yannick Cote](/assets/img/avatar_default.png)
In some cases, when an error occurs during testing and the main test routine returns, a memory leak occurs via leaving previously registered shadow variables allocated in the kernel as well as shadow_ptr list elements. From now on, in case of error, remove all allocated shadow variables and shadow_ptr struct elements. Signed-off-by: Yannick Cote <ycote@redhat.com> Reviewed-by: Petr Mladek <pmladek@suse.com> Reviewed-by: Kamalesh Babulal <kamalesh@linux.vnet.ibm.com> Acked-by: Miroslav Benes <mbenes@suse.cz> Acked-by: Joe Lawrence <joe.lawrence@redhat.com> Signed-off-by: Petr Mladek <pmladek@suse.com> Link: https://lore.kernel.org/r/20200603182058.109470-5-ycote@redhat.com
301 lines
7.6 KiB
C
301 lines
7.6 KiB
C
// SPDX-License-Identifier: GPL-2.0
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// Copyright (C) 2018 Joe Lawrence <joe.lawrence@redhat.com>
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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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#include <linux/module.h>
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#include <linux/kernel.h>
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#include <linux/list.h>
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#include <linux/livepatch.h>
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#include <linux/slab.h>
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/*
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* Keep a small list of pointers so that we can print address-agnostic
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* pointer values. Use a rolling integer count to differentiate the values.
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* Ironically we could have used the shadow variable API to do this, but
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* let's not lean too heavily on the very code we're testing.
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*/
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static LIST_HEAD(ptr_list);
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struct shadow_ptr {
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void *ptr;
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int id;
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struct list_head list;
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};
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static void free_ptr_list(void)
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{
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struct shadow_ptr *sp, *tmp_sp;
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list_for_each_entry_safe(sp, tmp_sp, &ptr_list, list) {
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list_del(&sp->list);
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kfree(sp);
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}
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}
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static int ptr_id(void *ptr)
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{
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struct shadow_ptr *sp;
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static int count;
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list_for_each_entry(sp, &ptr_list, list) {
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if (sp->ptr == ptr)
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return sp->id;
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}
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sp = kmalloc(sizeof(*sp), GFP_ATOMIC);
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if (!sp)
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return -ENOMEM;
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sp->ptr = ptr;
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sp->id = count++;
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list_add(&sp->list, &ptr_list);
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return sp->id;
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}
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/*
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* Shadow variable wrapper functions that echo the function and arguments
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* to the kernel log for testing verification. Don't display raw pointers,
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* but use the ptr_id() value instead.
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*/
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static void *shadow_get(void *obj, unsigned long id)
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{
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int **sv;
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sv = klp_shadow_get(obj, id);
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pr_info("klp_%s(obj=PTR%d, id=0x%lx) = PTR%d\n",
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__func__, ptr_id(obj), id, ptr_id(sv));
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return sv;
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}
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static void *shadow_alloc(void *obj, unsigned long id, size_t size,
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gfp_t gfp_flags, klp_shadow_ctor_t ctor,
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void *ctor_data)
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{
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int **var = ctor_data;
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int **sv;
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sv = klp_shadow_alloc(obj, id, size, gfp_flags, ctor, var);
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pr_info("klp_%s(obj=PTR%d, id=0x%lx, size=%zx, gfp_flags=%pGg), ctor=PTR%d, ctor_data=PTR%d = PTR%d\n",
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__func__, ptr_id(obj), id, size, &gfp_flags, ptr_id(ctor),
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ptr_id(*var), ptr_id(sv));
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return sv;
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}
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static void *shadow_get_or_alloc(void *obj, unsigned long id, size_t size,
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gfp_t gfp_flags, klp_shadow_ctor_t ctor,
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void *ctor_data)
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{
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int **var = ctor_data;
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int **sv;
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sv = klp_shadow_get_or_alloc(obj, id, size, gfp_flags, ctor, var);
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pr_info("klp_%s(obj=PTR%d, id=0x%lx, size=%zx, gfp_flags=%pGg), ctor=PTR%d, ctor_data=PTR%d = PTR%d\n",
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__func__, ptr_id(obj), id, size, &gfp_flags, ptr_id(ctor),
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ptr_id(*var), ptr_id(sv));
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return sv;
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}
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static void shadow_free(void *obj, unsigned long id, klp_shadow_dtor_t dtor)
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{
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klp_shadow_free(obj, id, dtor);
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pr_info("klp_%s(obj=PTR%d, id=0x%lx, dtor=PTR%d)\n",
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__func__, ptr_id(obj), id, ptr_id(dtor));
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}
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static void shadow_free_all(unsigned long id, klp_shadow_dtor_t dtor)
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{
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klp_shadow_free_all(id, dtor);
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pr_info("klp_%s(id=0x%lx, dtor=PTR%d)\n", __func__, id, ptr_id(dtor));
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}
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/* Shadow variable constructor - remember simple pointer data */
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static int shadow_ctor(void *obj, void *shadow_data, void *ctor_data)
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{
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int **sv = shadow_data;
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int **var = ctor_data;
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if (!var)
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return -EINVAL;
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*sv = *var;
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pr_info("%s: PTR%d -> PTR%d\n", __func__, ptr_id(sv), ptr_id(*var));
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return 0;
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}
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/*
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* With more than one item to free in the list, order is not determined and
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* shadow_dtor will not be passed to shadow_free_all() which would make the
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* test fail. (see pass 6)
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*/
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static void shadow_dtor(void *obj, void *shadow_data)
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{
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int **sv = shadow_data;
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pr_info("%s(obj=PTR%d, shadow_data=PTR%d)\n",
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__func__, ptr_id(obj), ptr_id(sv));
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}
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/* number of objects we simulate that need shadow vars */
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#define NUM_OBJS 3
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/* dynamically created obj fields have the following shadow var id values */
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#define SV_ID1 0x1234
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#define SV_ID2 0x1235
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/*
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* The main test case adds/removes new fields (shadow var) to each of these
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* test structure instances. The last group of fields in the struct represent
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* the idea that shadow variables may be added and removed to and from the
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* struct during execution.
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*/
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struct test_object {
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/* add anything here below and avoid to define an empty struct */
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struct shadow_ptr sp;
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/* these represent shadow vars added and removed with SV_ID{1,2} */
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/* char nfield1; */
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/* int nfield2; */
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};
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static int test_klp_shadow_vars_init(void)
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{
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struct test_object objs[NUM_OBJS];
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char nfields1[NUM_OBJS], *pnfields1[NUM_OBJS], **sv1[NUM_OBJS];
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char *pndup[NUM_OBJS];
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int nfields2[NUM_OBJS], *pnfields2[NUM_OBJS], **sv2[NUM_OBJS];
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void **sv;
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int ret;
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int i;
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ptr_id(NULL);
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/*
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* With an empty shadow variable hash table, expect not to find
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* any matches.
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*/
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sv = shadow_get(&objs[0], SV_ID1);
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if (!sv)
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pr_info(" got expected NULL result\n");
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/* pass 1: init & alloc a char+int pair of svars for each objs */
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for (i = 0; i < NUM_OBJS; i++) {
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pnfields1[i] = &nfields1[i];
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ptr_id(pnfields1[i]);
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if (i % 2) {
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sv1[i] = shadow_alloc(&objs[i], SV_ID1,
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sizeof(pnfields1[i]), GFP_KERNEL,
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shadow_ctor, &pnfields1[i]);
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} else {
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sv1[i] = shadow_get_or_alloc(&objs[i], SV_ID1,
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sizeof(pnfields1[i]), GFP_KERNEL,
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shadow_ctor, &pnfields1[i]);
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}
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if (!sv1[i]) {
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ret = -ENOMEM;
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goto out;
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}
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pnfields2[i] = &nfields2[i];
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ptr_id(pnfields2[i]);
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sv2[i] = shadow_alloc(&objs[i], SV_ID2, sizeof(pnfields2[i]),
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GFP_KERNEL, shadow_ctor, &pnfields2[i]);
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if (!sv2[i]) {
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ret = -ENOMEM;
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goto out;
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}
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}
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/* pass 2: verify we find allocated svars and where they point to */
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for (i = 0; i < NUM_OBJS; i++) {
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/* check the "char" svar for all objects */
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sv = shadow_get(&objs[i], SV_ID1);
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if (!sv) {
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ret = -EINVAL;
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goto out;
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}
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if ((char **)sv == sv1[i] && *sv1[i] == pnfields1[i])
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pr_info(" got expected PTR%d -> PTR%d result\n",
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ptr_id(sv1[i]), ptr_id(*sv1[i]));
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/* check the "int" svar for all objects */
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sv = shadow_get(&objs[i], SV_ID2);
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if (!sv) {
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ret = -EINVAL;
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goto out;
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}
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if ((int **)sv == sv2[i] && *sv2[i] == pnfields2[i])
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pr_info(" got expected PTR%d -> PTR%d result\n",
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ptr_id(sv2[i]), ptr_id(*sv2[i]));
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}
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/* pass 3: verify that 'get_or_alloc' returns already allocated svars */
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for (i = 0; i < NUM_OBJS; i++) {
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pndup[i] = &nfields1[i];
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ptr_id(pndup[i]);
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sv = shadow_get_or_alloc(&objs[i], SV_ID1, sizeof(pndup[i]),
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GFP_KERNEL, shadow_ctor, &pndup[i]);
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if (!sv) {
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ret = -EINVAL;
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goto out;
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}
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if ((char **)sv == sv1[i] && *sv1[i] == pnfields1[i])
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pr_info(" got expected PTR%d -> PTR%d result\n",
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ptr_id(sv1[i]), ptr_id(*sv1[i]));
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}
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/* pass 4: free <objs[*], SV_ID1> pairs of svars, verify removal */
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for (i = 0; i < NUM_OBJS; i++) {
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shadow_free(&objs[i], SV_ID1, shadow_dtor); /* 'char' pairs */
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sv = shadow_get(&objs[i], SV_ID1);
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if (!sv)
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pr_info(" got expected NULL result\n");
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}
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/* pass 5: check we still find <objs[*], SV_ID2> svar pairs */
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for (i = 0; i < NUM_OBJS; i++) {
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sv = shadow_get(&objs[i], SV_ID2); /* 'int' pairs */
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if (!sv) {
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ret = -EINVAL;
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goto out;
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}
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if ((int **)sv == sv2[i] && *sv2[i] == pnfields2[i])
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pr_info(" got expected PTR%d -> PTR%d result\n",
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ptr_id(sv2[i]), ptr_id(*sv2[i]));
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}
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/* pass 6: free all the <objs[*], SV_ID2> svar pairs too. */
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shadow_free_all(SV_ID2, NULL); /* 'int' pairs */
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for (i = 0; i < NUM_OBJS; i++) {
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sv = shadow_get(&objs[i], SV_ID2);
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if (!sv)
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pr_info(" got expected NULL result\n");
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}
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free_ptr_list();
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return 0;
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out:
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shadow_free_all(SV_ID1, NULL); /* 'char' pairs */
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shadow_free_all(SV_ID2, NULL); /* 'int' pairs */
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free_ptr_list();
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return ret;
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}
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static void test_klp_shadow_vars_exit(void)
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{
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}
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module_init(test_klp_shadow_vars_init);
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module_exit(test_klp_shadow_vars_exit);
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MODULE_LICENSE("GPL");
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MODULE_AUTHOR("Joe Lawrence <joe.lawrence@redhat.com>");
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MODULE_DESCRIPTION("Livepatch test: shadow variables");
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