Commit 8223967f authored by Alexei Starovoitov's avatar Alexei Starovoitov
Browse files

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 b471f2f1
("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: default avatarAlexei Starovoitov <ast@kernel.org>
parents 1651e39e af32efee

kernel/bpf/lpm_trie.c

+11 −15
Original line number Diff line number Diff line
@@ -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.
@@ -651,9 +647,9 @@ 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];

		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)) {
@@ -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]);

tools/testing/selftests/bpf/Makefile

+1 −1
Original line number Diff line number Diff line
@@ -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

tools/testing/selftests/bpf/test_lpm_map.c

+95 −0
Original line number Diff line number Diff line
@@ -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;

}

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