144 lines
3.2 KiB
C
144 lines
3.2 KiB
C
/*
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* This is for all the tests relating directly to heap memory, including
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* page allocation and slab allocations.
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*/
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#include "lkdtm.h"
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#include <linux/slab.h>
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#include <linux/sched.h>
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/*
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* This tries to stay within the next largest power-of-2 kmalloc cache
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* to avoid actually overwriting anything important if it's not detected
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* correctly.
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*/
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void lkdtm_OVERWRITE_ALLOCATION(void)
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{
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size_t len = 1020;
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u32 *data = kmalloc(len, GFP_KERNEL);
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data[1024 / sizeof(u32)] = 0x12345678;
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kfree(data);
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}
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void lkdtm_WRITE_AFTER_FREE(void)
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{
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int *base, *again;
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size_t len = 1024;
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/*
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* The slub allocator uses the first word to store the free
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* pointer in some configurations. Use the middle of the
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* allocation to avoid running into the freelist
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*/
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size_t offset = (len / sizeof(*base)) / 2;
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base = kmalloc(len, GFP_KERNEL);
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pr_info("Allocated memory %p-%p\n", base, &base[offset * 2]);
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pr_info("Attempting bad write to freed memory at %p\n",
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&base[offset]);
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kfree(base);
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base[offset] = 0x0abcdef0;
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/* Attempt to notice the overwrite. */
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again = kmalloc(len, GFP_KERNEL);
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kfree(again);
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if (again != base)
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pr_info("Hmm, didn't get the same memory range.\n");
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}
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void lkdtm_READ_AFTER_FREE(void)
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{
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int *base, *val, saw;
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size_t len = 1024;
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/*
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* The slub allocator uses the first word to store the free
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* pointer in some configurations. Use the middle of the
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* allocation to avoid running into the freelist
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*/
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size_t offset = (len / sizeof(*base)) / 2;
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base = kmalloc(len, GFP_KERNEL);
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if (!base) {
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pr_info("Unable to allocate base memory.\n");
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return;
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}
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val = kmalloc(len, GFP_KERNEL);
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if (!val) {
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pr_info("Unable to allocate val memory.\n");
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kfree(base);
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return;
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}
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*val = 0x12345678;
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base[offset] = *val;
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pr_info("Value in memory before free: %x\n", base[offset]);
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kfree(base);
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pr_info("Attempting bad read from freed memory\n");
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saw = base[offset];
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if (saw != *val) {
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/* Good! Poisoning happened, so declare a win. */
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pr_info("Memory correctly poisoned (%x)\n", saw);
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BUG();
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}
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pr_info("Memory was not poisoned\n");
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kfree(val);
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}
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void lkdtm_WRITE_BUDDY_AFTER_FREE(void)
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{
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unsigned long p = __get_free_page(GFP_KERNEL);
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if (!p) {
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pr_info("Unable to allocate free page\n");
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return;
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}
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pr_info("Writing to the buddy page before free\n");
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memset((void *)p, 0x3, PAGE_SIZE);
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free_page(p);
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schedule();
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pr_info("Attempting bad write to the buddy page after free\n");
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memset((void *)p, 0x78, PAGE_SIZE);
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/* Attempt to notice the overwrite. */
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p = __get_free_page(GFP_KERNEL);
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free_page(p);
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schedule();
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}
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void lkdtm_READ_BUDDY_AFTER_FREE(void)
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{
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unsigned long p = __get_free_page(GFP_KERNEL);
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int saw, *val;
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int *base;
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if (!p) {
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pr_info("Unable to allocate free page\n");
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return;
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}
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val = kmalloc(1024, GFP_KERNEL);
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if (!val) {
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pr_info("Unable to allocate val memory.\n");
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free_page(p);
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return;
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}
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base = (int *)p;
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*val = 0x12345678;
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base[0] = *val;
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pr_info("Value in memory before free: %x\n", base[0]);
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free_page(p);
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pr_info("Attempting to read from freed memory\n");
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saw = base[0];
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if (saw != *val) {
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/* Good! Poisoning happened, so declare a win. */
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pr_info("Memory correctly poisoned (%x)\n", saw);
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BUG();
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}
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pr_info("Buddy page was not poisoned\n");
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kfree(val);
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}
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