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Subject[PATCH net 3/3] net/smc: move sock lock in smc_ioctl()
Date
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@syzkaller.appspotmail.com
Reported-by: syzbot+19557374321ca3710990@syzkaller.appspotmail.com
Fixes: 1992d99882af ("net/smc: take sock lock in smc_ioctl()")
Signed-off-by: Ursula Braun <ubraun@linux.ibm.com>
---
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
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