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synced 2024-08-22 17:01:14 +00:00
![Matthew Wilcox](/assets/img/avatar_default.png)
There's a relatively rare race where we look at the per-cpu preallocated IDA bitmap, see it's NULL, allocate a new one, and atomically update it. If the kmalloc() happened to sleep and we were rescheduled to a different CPU, or an interrupt came in at the exact right time, another task might have successfully allocated a bitmap and already deposited it. I forgot what the semantics of cmpxchg() were and ended up freeing the wrong bitmap leading to KASAN reporting a use-after-free. Dmitry found the bug with syzkaller & wrote the patch. I wrote the test case that will reproduce the bug without his patch being applied. Reported-by: Dmitry Vyukov <dvyukov@google.com> Signed-off-by: Matthew Wilcox <mawilcox@microsoft.com>
386 lines
8.6 KiB
C
386 lines
8.6 KiB
C
#include <stdio.h>
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#include <stdlib.h>
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#include <unistd.h>
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#include <time.h>
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#include <assert.h>
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#include <limits.h>
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#include <linux/slab.h>
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#include <linux/radix-tree.h>
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#include "test.h"
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#include "regression.h"
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void __gang_check(unsigned long middle, long down, long up, int chunk, int hop)
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{
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long idx;
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RADIX_TREE(tree, GFP_KERNEL);
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middle = 1 << 30;
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for (idx = -down; idx < up; idx++)
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item_insert(&tree, middle + idx);
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item_check_absent(&tree, middle - down - 1);
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for (idx = -down; idx < up; idx++)
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item_check_present(&tree, middle + idx);
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item_check_absent(&tree, middle + up);
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item_gang_check_present(&tree, middle - down,
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up + down, chunk, hop);
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item_full_scan(&tree, middle - down, down + up, chunk);
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item_kill_tree(&tree);
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}
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void gang_check(void)
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{
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__gang_check(1 << 30, 128, 128, 35, 2);
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__gang_check(1 << 31, 128, 128, 32, 32);
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__gang_check(1 << 31, 128, 128, 32, 100);
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__gang_check(1 << 31, 128, 128, 17, 7);
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__gang_check(0xffff0000, 0, 65536, 17, 7);
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__gang_check(0xfffffffe, 1, 1, 17, 7);
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}
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void __big_gang_check(void)
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{
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unsigned long start;
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int wrapped = 0;
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start = 0;
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do {
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unsigned long old_start;
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// printf("0x%08lx\n", start);
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__gang_check(start, rand() % 113 + 1, rand() % 71,
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rand() % 157, rand() % 91 + 1);
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old_start = start;
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start += rand() % 1000000;
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start %= 1ULL << 33;
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if (start < old_start)
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wrapped = 1;
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} while (!wrapped);
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}
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void big_gang_check(bool long_run)
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{
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int i;
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for (i = 0; i < (long_run ? 1000 : 3); i++) {
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__big_gang_check();
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printv(2, "%d ", i);
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fflush(stdout);
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}
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}
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void add_and_check(void)
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{
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RADIX_TREE(tree, GFP_KERNEL);
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item_insert(&tree, 44);
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item_check_present(&tree, 44);
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item_check_absent(&tree, 43);
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item_kill_tree(&tree);
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}
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void dynamic_height_check(void)
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{
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int i;
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RADIX_TREE(tree, GFP_KERNEL);
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tree_verify_min_height(&tree, 0);
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item_insert(&tree, 42);
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tree_verify_min_height(&tree, 42);
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item_insert(&tree, 1000000);
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tree_verify_min_height(&tree, 1000000);
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assert(item_delete(&tree, 1000000));
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tree_verify_min_height(&tree, 42);
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assert(item_delete(&tree, 42));
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tree_verify_min_height(&tree, 0);
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for (i = 0; i < 1000; i++) {
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item_insert(&tree, i);
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tree_verify_min_height(&tree, i);
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}
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i--;
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for (;;) {
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assert(item_delete(&tree, i));
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if (i == 0) {
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tree_verify_min_height(&tree, 0);
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break;
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}
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i--;
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tree_verify_min_height(&tree, i);
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}
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item_kill_tree(&tree);
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}
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void check_copied_tags(struct radix_tree_root *tree, unsigned long start, unsigned long end, unsigned long *idx, int count, int fromtag, int totag)
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{
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int i;
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for (i = 0; i < count; i++) {
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/* if (i % 1000 == 0)
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putchar('.'); */
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if (idx[i] < start || idx[i] > end) {
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if (item_tag_get(tree, idx[i], totag)) {
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printv(2, "%lu-%lu: %lu, tags %d-%d\n", start,
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end, idx[i], item_tag_get(tree, idx[i],
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fromtag),
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item_tag_get(tree, idx[i], totag));
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}
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assert(!item_tag_get(tree, idx[i], totag));
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continue;
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}
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if (item_tag_get(tree, idx[i], fromtag) ^
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item_tag_get(tree, idx[i], totag)) {
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printv(2, "%lu-%lu: %lu, tags %d-%d\n", start, end,
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idx[i], item_tag_get(tree, idx[i], fromtag),
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item_tag_get(tree, idx[i], totag));
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}
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assert(!(item_tag_get(tree, idx[i], fromtag) ^
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item_tag_get(tree, idx[i], totag)));
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}
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}
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#define ITEMS 50000
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void copy_tag_check(void)
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{
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RADIX_TREE(tree, GFP_KERNEL);
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unsigned long idx[ITEMS];
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unsigned long start, end, count = 0, tagged, cur, tmp;
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int i;
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// printf("generating radix tree indices...\n");
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start = rand();
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end = rand();
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if (start > end && (rand() % 10)) {
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cur = start;
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start = end;
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end = cur;
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}
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/* Specifically create items around the start and the end of the range
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* with high probability to check for off by one errors */
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cur = rand();
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if (cur & 1) {
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item_insert(&tree, start);
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if (cur & 2) {
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if (start <= end)
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count++;
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item_tag_set(&tree, start, 0);
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}
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}
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if (cur & 4) {
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item_insert(&tree, start-1);
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if (cur & 8)
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item_tag_set(&tree, start-1, 0);
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}
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if (cur & 16) {
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item_insert(&tree, end);
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if (cur & 32) {
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if (start <= end)
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count++;
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item_tag_set(&tree, end, 0);
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}
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}
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if (cur & 64) {
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item_insert(&tree, end+1);
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if (cur & 128)
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item_tag_set(&tree, end+1, 0);
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}
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for (i = 0; i < ITEMS; i++) {
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do {
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idx[i] = rand();
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} while (item_lookup(&tree, idx[i]));
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item_insert(&tree, idx[i]);
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if (rand() & 1) {
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item_tag_set(&tree, idx[i], 0);
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if (idx[i] >= start && idx[i] <= end)
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count++;
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}
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/* if (i % 1000 == 0)
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putchar('.'); */
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}
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// printf("\ncopying tags...\n");
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tagged = tag_tagged_items(&tree, NULL, start, end, ITEMS, 0, 1);
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// printf("checking copied tags\n");
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assert(tagged == count);
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check_copied_tags(&tree, start, end, idx, ITEMS, 0, 1);
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/* Copy tags in several rounds */
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// printf("\ncopying tags...\n");
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tmp = rand() % (count / 10 + 2);
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tagged = tag_tagged_items(&tree, NULL, start, end, tmp, 0, 2);
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assert(tagged == count);
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// printf("%lu %lu %lu\n", tagged, tmp, count);
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// printf("checking copied tags\n");
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check_copied_tags(&tree, start, end, idx, ITEMS, 0, 2);
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verify_tag_consistency(&tree, 0);
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verify_tag_consistency(&tree, 1);
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verify_tag_consistency(&tree, 2);
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// printf("\n");
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item_kill_tree(&tree);
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}
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static void __locate_check(struct radix_tree_root *tree, unsigned long index,
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unsigned order)
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{
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struct item *item;
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unsigned long index2;
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item_insert_order(tree, index, order);
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item = item_lookup(tree, index);
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index2 = find_item(tree, item);
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if (index != index2) {
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printv(2, "index %ld order %d inserted; found %ld\n",
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index, order, index2);
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abort();
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}
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}
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static void __order_0_locate_check(void)
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{
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RADIX_TREE(tree, GFP_KERNEL);
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int i;
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for (i = 0; i < 50; i++)
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__locate_check(&tree, rand() % INT_MAX, 0);
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item_kill_tree(&tree);
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}
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static void locate_check(void)
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{
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RADIX_TREE(tree, GFP_KERNEL);
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unsigned order;
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unsigned long offset, index;
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__order_0_locate_check();
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for (order = 0; order < 20; order++) {
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for (offset = 0; offset < (1 << (order + 3));
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offset += (1UL << order)) {
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for (index = 0; index < (1UL << (order + 5));
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index += (1UL << order)) {
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__locate_check(&tree, index + offset, order);
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}
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if (find_item(&tree, &tree) != -1)
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abort();
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item_kill_tree(&tree);
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}
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}
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if (find_item(&tree, &tree) != -1)
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abort();
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__locate_check(&tree, -1, 0);
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if (find_item(&tree, &tree) != -1)
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abort();
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item_kill_tree(&tree);
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}
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static void single_thread_tests(bool long_run)
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{
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int i;
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printv(1, "starting single_thread_tests: %d allocated, preempt %d\n",
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nr_allocated, preempt_count);
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multiorder_checks();
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rcu_barrier();
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printv(2, "after multiorder_check: %d allocated, preempt %d\n",
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nr_allocated, preempt_count);
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locate_check();
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rcu_barrier();
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printv(2, "after locate_check: %d allocated, preempt %d\n",
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nr_allocated, preempt_count);
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tag_check();
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rcu_barrier();
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printv(2, "after tag_check: %d allocated, preempt %d\n",
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nr_allocated, preempt_count);
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gang_check();
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rcu_barrier();
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printv(2, "after gang_check: %d allocated, preempt %d\n",
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nr_allocated, preempt_count);
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add_and_check();
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rcu_barrier();
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printv(2, "after add_and_check: %d allocated, preempt %d\n",
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nr_allocated, preempt_count);
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dynamic_height_check();
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rcu_barrier();
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printv(2, "after dynamic_height_check: %d allocated, preempt %d\n",
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nr_allocated, preempt_count);
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idr_checks();
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ida_checks();
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rcu_barrier();
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printv(2, "after idr_checks: %d allocated, preempt %d\n",
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nr_allocated, preempt_count);
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big_gang_check(long_run);
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rcu_barrier();
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printv(2, "after big_gang_check: %d allocated, preempt %d\n",
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nr_allocated, preempt_count);
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for (i = 0; i < (long_run ? 2000 : 3); i++) {
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copy_tag_check();
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printv(2, "%d ", i);
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fflush(stdout);
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}
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rcu_barrier();
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printv(2, "after copy_tag_check: %d allocated, preempt %d\n",
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nr_allocated, preempt_count);
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}
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int main(int argc, char **argv)
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{
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bool long_run = false;
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int opt;
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unsigned int seed = time(NULL);
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while ((opt = getopt(argc, argv, "ls:v")) != -1) {
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if (opt == 'l')
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long_run = true;
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else if (opt == 's')
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seed = strtoul(optarg, NULL, 0);
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else if (opt == 'v')
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test_verbose++;
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}
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printf("random seed %u\n", seed);
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srand(seed);
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printf("running tests\n");
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rcu_register_thread();
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radix_tree_init();
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regression1_test();
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regression2_test();
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regression3_test();
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iteration_test(0, 10 + 90 * long_run);
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iteration_test(7, 10 + 90 * long_run);
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single_thread_tests(long_run);
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ida_thread_tests();
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/* Free any remaining preallocated nodes */
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radix_tree_cpu_dead(0);
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benchmark();
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rcu_barrier();
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printv(2, "after rcu_barrier: %d allocated, preempt %d\n",
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nr_allocated, preempt_count);
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rcu_unregister_thread();
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printf("tests completed\n");
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exit(0);
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}
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