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| author | Jakub Sitnicki <jakub@cloudflare.com> | 2024-04-02 12:46:21 +0200 |
|---|---|---|
| committer | Daniel Borkmann <daniel@iogearbox.net> | 2024-04-02 16:31:05 +0200 |
| commit | ff91059932401894e6c86341915615c5eb0eca48 (patch) | |
| tree | 2a7b401e3f18c6df1de80a3833228250aaaa9211 /net | |
| parent | 8c3fe029d79ada599fa558fdf3da0322fc38de36 (diff) | |
| download | linux-stable-ff91059932401894e6c86341915615c5eb0eca48.tar.gz linux-stable-ff91059932401894e6c86341915615c5eb0eca48.tar.bz2 linux-stable-ff91059932401894e6c86341915615c5eb0eca48.zip | |
bpf, sockmap: Prevent lock inversion deadlock in map delete elem
syzkaller started using corpuses where a BPF tracing program deletes
elements from a sockmap/sockhash map. Because BPF tracing programs can be
invoked from any interrupt context, locks taken during a map_delete_elem
operation must be hardirq-safe. Otherwise a deadlock due to lock inversion
is possible, as reported by lockdep:
CPU0 CPU1
---- ----
lock(&htab->buckets[i].lock);
local_irq_disable();
lock(&host->lock);
lock(&htab->buckets[i].lock);
<Interrupt>
lock(&host->lock);
Locks in sockmap are hardirq-unsafe by design. We expects elements to be
deleted from sockmap/sockhash only in task (normal) context with interrupts
enabled, or in softirq context.
Detect when map_delete_elem operation is invoked from a context which is
_not_ hardirq-unsafe, that is interrupts are disabled, and bail out with an
error.
Note that map updates are not affected by this issue. BPF verifier does not
allow updating sockmap/sockhash from a BPF tracing program today.
Fixes: 604326b41a6f ("bpf, sockmap: convert to generic sk_msg interface")
Reported-by: xingwei lee <xrivendell7@gmail.com>
Reported-by: yue sun <samsun1006219@gmail.com>
Reported-by: syzbot+bc922f476bd65abbd466@syzkaller.appspotmail.com
Reported-by: syzbot+d4066896495db380182e@syzkaller.appspotmail.com
Signed-off-by: Jakub Sitnicki <jakub@cloudflare.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Tested-by: syzbot+d4066896495db380182e@syzkaller.appspotmail.com
Acked-by: John Fastabend <john.fastabend@gmail.com>
Closes: https://syzkaller.appspot.com/bug?extid=d4066896495db380182e
Closes: https://syzkaller.appspot.com/bug?extid=bc922f476bd65abbd466
Link: https://lore.kernel.org/bpf/20240402104621.1050319-1-jakub@cloudflare.com
Diffstat (limited to 'net')
| -rw-r--r-- | net/core/sock_map.c | 6 |
1 files changed, 6 insertions, 0 deletions
diff --git a/net/core/sock_map.c b/net/core/sock_map.c index 27d733c0f65e..8598466a3805 100644 --- a/net/core/sock_map.c +++ b/net/core/sock_map.c @@ -411,6 +411,9 @@ static int __sock_map_delete(struct bpf_stab *stab, struct sock *sk_test, struct sock *sk; int err = 0; + if (irqs_disabled()) + return -EOPNOTSUPP; /* locks here are hardirq-unsafe */ + spin_lock_bh(&stab->lock); sk = *psk; if (!sk_test || sk_test == sk) @@ -933,6 +936,9 @@ static long sock_hash_delete_elem(struct bpf_map *map, void *key) struct bpf_shtab_elem *elem; int ret = -ENOENT; + if (irqs_disabled()) + return -EOPNOTSUPP; /* locks here are hardirq-unsafe */ + hash = sock_hash_bucket_hash(key, key_size); bucket = sock_hash_select_bucket(htab, hash); |