diff options
| author |   Liu Jian <liujian56@huawei.com> | 2022-08-09 17:49:15 +0800 |
|---|---|---|
| committer |   Daniel Borkmann <daniel@iogearbox.net> | 2022-08-17 22:33:20 +0200 |
| commit | 583585e48d965338e73e1eb383768d16e0922d73 (patch) | |
| tree | 0ee9ea24f129d2a7d9f3747034fb0fe315ec5bce | |
| parent | xsk: Fix corrupted packets for XDP_SHARED_UMEM (diff) | |
| download | linux-dev-583585e48d965338e73e1eb383768d16e0922d73.tar.xz linux-dev-583585e48d965338e73e1eb383768d16e0922d73.zip | |
skmsg: Fix wrong last sg check in sk_msg_recvmsg()
Fix one kernel NULL pointer dereference as below:
[ 224.462334] Call Trace:
[ 224.462394] __tcp_bpf_recvmsg+0xd3/0x380
[ 224.462441] ? sock_has_perm+0x78/0xa0
[ 224.462463] tcp_bpf_recvmsg+0x12e/0x220
[ 224.462494] inet_recvmsg+0x5b/0xd0
[ 224.462534] __sys_recvfrom+0xc8/0x130
[ 224.462574] ? syscall_trace_enter+0x1df/0x2e0
[ 224.462606] ? __do_page_fault+0x2de/0x500
[ 224.462635] __x64_sys_recvfrom+0x24/0x30
[ 224.462660] do_syscall_64+0x5d/0x1d0
[ 224.462709] entry_SYSCALL_64_after_hwframe+0x65/0xca
In commit 9974d37ea75f ("skmsg: Fix invalid last sg check in
sk_msg_recvmsg()"), we change last sg check to sg_is_last(),
but in sockmap redirection case (without stream_parser/stream_verdict/
skb_verdict), we did not mark the end of the scatterlist. Check the
sk_msg_alloc, sk_msg_page_add, and bpf_msg_push_data functions, they all
do not mark the end of sg. They are expected to use sg.end for end
judgment. So the judgment of '(i != msg_rx->sg.end)' is added back here.
Fixes: 9974d37ea75f ("skmsg: Fix invalid last sg check in sk_msg_recvmsg()")
Signed-off-by: Liu Jian <liujian56@huawei.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Acked-by: Jakub Sitnicki <jakub@cloudflare.com>
Link: https://lore.kernel.org/bpf/20220809094915.150391-1-liujian56@huawei.com
| -rw-r--r-- | net/core/skmsg.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/net/core/skmsg.c b/net/core/skmsg.c index f47338d89d5d..5be4485ff07d 100644 --- a/net/core/skmsg.c +++ b/net/core/skmsg.c @@ -461,7 +461,7 @@ int sk_msg_recvmsg(struct sock *sk, struct sk_psock *psock, struct msghdr *msg, if (copied == len) break; - } while (!sg_is_last(sge)); + } while ((i != msg_rx->sg.end) && !sg_is_last(sge)); if (unlikely(peek)) { msg_rx = sk_psock_next_msg(psock, msg_rx); @@ -471,7 +471,7 @@ int sk_msg_recvmsg(struct sock *sk, struct sk_psock *psock, struct msghdr *msg, } msg_rx->sg.start = i; - if (!sge->length && sg_is_last(sge)) { + if (!sge->length && (i == msg_rx->sg.end || sg_is_last(sge))) { msg_rx = sk_psock_dequeue_msg(psock); kfree_sk_msg(msg_rx); } |