]> git.proxmox.com Git - mirror_ubuntu-eoan-kernel.git/commitdiff
bpf: fix incorrect kmalloc usage in lpm_trie MAP_GET_NEXT_KEY rcu region
authorYonghong Song <yhs@fb.com>
Tue, 23 Jan 2018 06:53:51 +0000 (22:53 -0800)
committerDaniel Borkmann <daniel@iogearbox.net>
Tue, 23 Jan 2018 16:33:57 +0000 (17:33 +0100)
In commit b471f2f1de8b ("bpf: implement MAP_GET_NEXT_KEY command for LPM_TRIE map"),
the implemented MAP_GET_NEXT_KEY callback function is guarded with rcu read lock.
In the function body, "kmalloc(size, GFP_USER | __GFP_NOWARN)" is used which may
sleep and violate rcu read lock region requirements. This patch fixed the issue
by using GFP_ATOMIC instead to avoid blocking kmalloc. Tested with
CONFIG_DEBUG_ATOMIC_SLEEP=y as suggested by Eric Dumazet.

Fixes: b471f2f1de8b ("bpf: implement MAP_GET_NEXT_KEY command for LPM_TRIE map")
Signed-off-by: Yonghong Song <yhs@fb.com>
Reported-by: syzbot <syzkaller@googlegroups.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
kernel/bpf/lpm_trie.c

index d7ea9621851650da7cc2ec51fb8b550a57081353..8f083ea9d4b9c11880a742f8aaaa3cd9527146bb 100644 (file)
@@ -624,7 +624,7 @@ static int trie_get_next_key(struct bpf_map *map, void *_key, void *_next_key)
        }
 
        node_stack = kmalloc(trie->max_prefixlen * sizeof(struct lpm_trie_node *),
-                            GFP_USER | __GFP_NOWARN);
+                            GFP_ATOMIC | __GFP_NOWARN);
        if (!node_stack)
                return -ENOMEM;