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author | WANG Cong <xiyou.wangcong@gmail.com> | 2017-02-07 12:59:47 -0800 |
---|---|---|
committer | David S. Miller <davem@davemloft.net> | 2017-02-09 16:38:48 -0500 |
commit | 98e3862ca2b1ae595a13805dcab4c3a6d7718f4d (patch) | |
tree | 52879528ae93a9cc7aec463a1f1d1653c3da967f /net | |
parent | 538d92912d3190a1dd809233a0d57277459f37b2 (diff) | |
download | linux-98e3862ca2b1ae595a13805dcab4c3a6d7718f4d.tar.gz linux-98e3862ca2b1ae595a13805dcab4c3a6d7718f4d.tar.bz2 linux-98e3862ca2b1ae595a13805dcab4c3a6d7718f4d.zip |
kcm: fix 0-length case for kcm_sendmsg()
Dmitry reported a kernel warning:
WARNING: CPU: 3 PID: 2936 at net/kcm/kcmsock.c:627
kcm_write_msgs+0x12e3/0x1b90 net/kcm/kcmsock.c:627
CPU: 3 PID: 2936 Comm: a.out Not tainted 4.10.0-rc6+ #209
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011
Call Trace:
__dump_stack lib/dump_stack.c:15 [inline]
dump_stack+0x2ee/0x3ef lib/dump_stack.c:51
panic+0x1fb/0x412 kernel/panic.c:179
__warn+0x1c4/0x1e0 kernel/panic.c:539
warn_slowpath_null+0x2c/0x40 kernel/panic.c:582
kcm_write_msgs+0x12e3/0x1b90 net/kcm/kcmsock.c:627
kcm_sendmsg+0x163a/0x2200 net/kcm/kcmsock.c:1029
sock_sendmsg_nosec net/socket.c:635 [inline]
sock_sendmsg+0xca/0x110 net/socket.c:645
sock_write_iter+0x326/0x600 net/socket.c:848
new_sync_write fs/read_write.c:499 [inline]
__vfs_write+0x483/0x740 fs/read_write.c:512
vfs_write+0x187/0x530 fs/read_write.c:560
SYSC_write fs/read_write.c:607 [inline]
SyS_write+0xfb/0x230 fs/read_write.c:599
entry_SYSCALL_64_fastpath+0x1f/0xc2
when calling syscall(__NR_write, sock2, 0x208aaf27ul, 0x0ul) on a KCM
seqpacket socket. It appears that kcm_sendmsg() does not handle len==0
case correctly, which causes an empty skb is allocated and queued.
Fix this by skipping the skb allocation for len==0 case.
Reported-by: Dmitry Vyukov <dvyukov@google.com>
Cc: Tom Herbert <tom@herbertland.com>
Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net')
-rw-r--r-- | net/kcm/kcmsock.c | 40 |
1 files changed, 22 insertions, 18 deletions
diff --git a/net/kcm/kcmsock.c b/net/kcm/kcmsock.c index 7e08a4d3d77d..64f0e8531af0 100644 --- a/net/kcm/kcmsock.c +++ b/net/kcm/kcmsock.c @@ -929,23 +929,25 @@ static int kcm_sendmsg(struct socket *sock, struct msghdr *msg, size_t len) goto out_error; } - /* New message, alloc head skb */ - head = alloc_skb(0, sk->sk_allocation); - while (!head) { - kcm_push(kcm); - err = sk_stream_wait_memory(sk, &timeo); - if (err) - goto out_error; - + if (msg_data_left(msg)) { + /* New message, alloc head skb */ head = alloc_skb(0, sk->sk_allocation); - } + while (!head) { + kcm_push(kcm); + err = sk_stream_wait_memory(sk, &timeo); + if (err) + goto out_error; - skb = head; + head = alloc_skb(0, sk->sk_allocation); + } - /* Set ip_summed to CHECKSUM_UNNECESSARY to avoid calling - * csum_and_copy_from_iter from skb_do_copy_data_nocache. - */ - skb->ip_summed = CHECKSUM_UNNECESSARY; + skb = head; + + /* Set ip_summed to CHECKSUM_UNNECESSARY to avoid calling + * csum_and_copy_from_iter from skb_do_copy_data_nocache. + */ + skb->ip_summed = CHECKSUM_UNNECESSARY; + } start: while (msg_data_left(msg)) { @@ -1018,10 +1020,12 @@ wait_for_memory: if (eor) { bool not_busy = skb_queue_empty(&sk->sk_write_queue); - /* Message complete, queue it on send buffer */ - __skb_queue_tail(&sk->sk_write_queue, head); - kcm->seq_skb = NULL; - KCM_STATS_INCR(kcm->stats.tx_msgs); + if (head) { + /* Message complete, queue it on send buffer */ + __skb_queue_tail(&sk->sk_write_queue, head); + kcm->seq_skb = NULL; + KCM_STATS_INCR(kcm->stats.tx_msgs); + } if (msg->msg_flags & MSG_BATCH) { kcm->tx_wait_more = true; |