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Merge branch 'fix-lpm-map' 

Yonghong Song says:

====================
A kernel page fault which happens in lpm map trie_get_next_key is reported
by syzbot and Eric. The issue was introduced by commit b471f2f1de
("bpf: implement MAP_GET_NEXT_KEY command for LPM_TRIE map").
Patch #1 fixed the issue in the kernel and patch #2 adds a multithreaded
test case in tools/testing/selftests/bpf/test_lpm_map.
====================

Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Alexei Starovoitov 2018-01-26 17:06:23 -08:00
parent 1651e39e4a af32efeede
commit 8223967fe0
3 changed files with 107 additions and 16 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

26
kernel/bpf/lpm_trie.c
View File

@ -593,11 +593,10 @@ unlock:
static int trie_get_next_key(struct bpf_map *map, void *_key, void *_next_key)
{
struct lpm_trie_node *node, *next_node = NULL, *parent, *search_root;
struct lpm_trie *trie = container_of(map, struct lpm_trie, map);
struct bpf_lpm_trie_key *key = _key, *next_key = _next_key;
struct lpm_trie_node *node, *next_node = NULL, *parent;
struct lpm_trie_node **node_stack = NULL;
struct lpm_trie_node __rcu **root;
int err = 0, stack_ptr = -1;
unsigned int next_bit;
size_t matchlen;
@ -614,14 +613,13 @@ static int trie_get_next_key(struct bpf_map *map, void *_key, void *_next_key)
*/
/* Empty trie */
if (!rcu_dereference(trie->root))
search_root = rcu_dereference(trie->root);
if (!search_root)
return -ENOENT;
/* For invalid key, find the leftmost node in the trie */
if (!key || key->prefixlen > trie->max_prefixlen) {
root = &trie->root;
if (!key || key->prefixlen > trie->max_prefixlen)
goto find_leftmost;
}
node_stack = kmalloc(trie->max_prefixlen * sizeof(struct lpm_trie_node *),
GFP_ATOMIC | __GFP_NOWARN);
@ -629,7 +627,7 @@ static int trie_get_next_key(struct bpf_map *map, void *_key, void *_next_key)
return -ENOMEM;
/* Try to find the exact node for the given key */
for (node = rcu_dereference(trie->root); node;) {
for (node = search_root; node;) {
node_stack[++stack_ptr] = node;
matchlen = longest_prefix_match(trie, node, key);
if (node->prefixlen != matchlen ||
@ -640,10 +638,8 @@ static int trie_get_next_key(struct bpf_map *map, void *_key, void *_next_key)
node = rcu_dereference(node->child[next_bit]);
}
if (!node || node->prefixlen != key->prefixlen ||
(node->flags & LPM_TREE_NODE_FLAG_IM)) {
root = &trie->root;
(node->flags & LPM_TREE_NODE_FLAG_IM))
goto find_leftmost;
}
/* The node with the exactly-matching key has been found,
* find the first node in postorder after the matched node.
@ -651,10 +647,10 @@ static int trie_get_next_key(struct bpf_map *map, void *_key, void *_next_key)
node = node_stack[stack_ptr];
while (stack_ptr > 0) {
parent = node_stack[stack_ptr - 1];
if (rcu_dereference(parent->child[0]) == node &&
rcu_dereference(parent->child[1])) {
root = &parent->child[1];
goto find_leftmost;
if (rcu_dereference(parent->child[0]) == node) {
search_root = rcu_dereference(parent->child[1]);
if (search_root)
goto find_leftmost;
}
if (!(parent->flags & LPM_TREE_NODE_FLAG_IM)) {
next_node = parent;
@ -673,7 +669,7 @@ find_leftmost:
/* Find the leftmost non-intermediate node, all intermediate nodes
* have exact two children, so this function will never return NULL.
*/
for (node = rcu_dereference(*root); node;) {
for (node = search_root; node;) {
if (!(node->flags & LPM_TREE_NODE_FLAG_IM))
next_node = node;
node = rcu_dereference(node->child[0]);

2
tools/testing/selftests/bpf/Makefile
View File

@ -11,7 +11,7 @@ ifneq ($(wildcard $(GENHDR)),)
endif
CFLAGS += -Wall -O2 -I$(APIDIR) -I$(LIBDIR) -I$(GENDIR) $(GENFLAGS) -I../../../include
LDLIBS += -lcap -lelf -lrt
LDLIBS += -lcap -lelf -lrt -lpthread
TEST_GEN_PROGS = test_verifier test_tag test_maps test_lru_map test_lpm_map test_progs \
test_align test_verifier_log test_dev_cgroup test_tcpbpf_user

95
tools/testing/selftests/bpf/test_lpm_map.c
View File

@ -14,6 +14,7 @@
#include <errno.h>
#include <inttypes.h>
#include <linux/bpf.h>
#include <pthread.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
@ -641,6 +642,98 @@ static void test_lpm_get_next_key(void)
close(map_fd);
}
#define MAX_TEST_KEYS 4
struct lpm_mt_test_info {
int cmd; /* 0: update, 1: delete, 2: lookup, 3: get_next_key */
int iter;
int map_fd;
struct {
__u32 prefixlen;
__u32 data;
} key[MAX_TEST_KEYS];
};
static void *lpm_test_command(void *arg)
{
int i, j, ret, iter, key_size;
struct lpm_mt_test_info *info = arg;
struct bpf_lpm_trie_key *key_p;
key_size = sizeof(struct bpf_lpm_trie_key) + sizeof(__u32);
key_p = alloca(key_size);
for (iter = 0; iter < info->iter; iter++)
for (i = 0; i < MAX_TEST_KEYS; i++) {
/* first half of iterations in forward order,
* and second half in backward order.
*/
j = (iter < (info->iter / 2)) ? i : MAX_TEST_KEYS - i - 1;
key_p->prefixlen = info->key[j].prefixlen;
memcpy(key_p->data, &info->key[j].data, sizeof(__u32));
if (info->cmd == 0) {
__u32 value = j;
/* update must succeed */
assert(bpf_map_update_elem(info->map_fd, key_p, &value, 0) == 0);
} else if (info->cmd == 1) {
ret = bpf_map_delete_elem(info->map_fd, key_p);
assert(ret == 0 || errno == ENOENT);
} else if (info->cmd == 2) {
__u32 value;
ret = bpf_map_lookup_elem(info->map_fd, key_p, &value);
assert(ret == 0 || errno == ENOENT);
} else {
struct bpf_lpm_trie_key *next_key_p = alloca(key_size);
ret = bpf_map_get_next_key(info->map_fd, key_p, next_key_p);
assert(ret == 0 || errno == ENOENT || errno == ENOMEM);
}
}
// Pass successful exit info back to the main thread
pthread_exit((void *)info);
}
static void setup_lpm_mt_test_info(struct lpm_mt_test_info *info, int map_fd)
{
info->iter = 2000;
info->map_fd = map_fd;
info->key[0].prefixlen = 16;
inet_pton(AF_INET, "192.168.0.0", &info->key[0].data);
info->key[1].prefixlen = 24;
inet_pton(AF_INET, "192.168.0.0", &info->key[1].data);
info->key[2].prefixlen = 24;
inet_pton(AF_INET, "192.168.128.0", &info->key[2].data);
info->key[3].prefixlen = 24;
inet_pton(AF_INET, "192.168.1.0", &info->key[3].data);
}
static void test_lpm_multi_thread(void)
{
struct lpm_mt_test_info info[4];
size_t key_size, value_size;
pthread_t thread_id[4];
int i, map_fd;
void *ret;
/* create a trie */
value_size = sizeof(__u32);
key_size = sizeof(struct bpf_lpm_trie_key) + value_size;
map_fd = bpf_create_map(BPF_MAP_TYPE_LPM_TRIE, key_size, value_size,
100, BPF_F_NO_PREALLOC);
/* create 4 threads to test update, delete, lookup and get_next_key */
setup_lpm_mt_test_info(&info[0], map_fd);
for (i = 0; i < 4; i++) {
if (i != 0)
memcpy(&info[i], &info[0], sizeof(info[i]));
info[i].cmd = i;
assert(pthread_create(&thread_id[i], NULL, &lpm_test_command, &info[i]) == 0);
}
for (i = 0; i < 4; i++)
assert(pthread_join(thread_id[i], &ret) == 0 && ret == (void *)&info[i]);
close(map_fd);
}
int main(void)
{
struct rlimit limit = { RLIM_INFINITY, RLIM_INFINITY };
@ -667,6 +760,8 @@ int main(void)
test_lpm_get_next_key();
test_lpm_multi_thread();
printf("test_lpm: OK\n");
return 0;
}