When an SMC socket is connecting it is decided whether fallback to TCP is needed. To avoid races between connect and ioctl move the sock lock before the use_fallback check. Reported-by: syzbot+5b2cece1a8ecb2ca77d8@xxxxxxxxxxxxxxxxxxxxxxxxx Reported-by: syzbot+19557374321ca3710990@xxxxxxxxxxxxxxxxxxxxxxxxx Fixes: 1992d99882af ("net/smc: take sock lock in smc_ioctl()") Signed-off-by: Ursula Braun <ubraun@xxxxxxxxxxxxx> --- net/smc/af_smc.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-) diff --git a/net/smc/af_smc.c b/net/smc/af_smc.c index 0ee7721afbe5..e7de5f282722 100644 --- a/net/smc/af_smc.c +++ b/net/smc/af_smc.c @@ -1522,12 +1522,16 @@ static int smc_ioctl(struct socket *sock, unsigned int cmd, smc = smc_sk(sock->sk); conn = &smc->conn; + lock_sock(&smc->sk); if (smc->use_fallback) { - if (!smc->clcsock) + if (!smc->clcsock) { + release_sock(&smc->sk); return -EBADF; - return smc->clcsock->ops->ioctl(smc->clcsock, cmd, arg); + } + answ = smc->clcsock->ops->ioctl(smc->clcsock, cmd, arg); + release_sock(&smc->sk); + return answ; } - lock_sock(&smc->sk); switch (cmd) { case SIOCINQ: /* same as FIONREAD */ if (smc->sk.sk_state == SMC_LISTEN) { -- 2.16.4 -- To unsubscribe from this list: send the line "unsubscribe linux-s390" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html