From: Cong Wang Date: Sun, 6 Jan 2019 07:45:26 +0000 (-0800) Subject: smc: move unhash as early as possible in smc_release() X-Git-Tag: v4.19.17~76 X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=8dc262df0c6f304657a0d6db071a7287390307af;p=users%2Fdwmw2%2Flinux.git smc: move unhash as early as possible in smc_release() [ Upstream commit 26d92e951fe0a44ee4aec157cabb65a818cc8151 ] In smc_release() we release smc->clcsock before unhash the smc sock, but a parallel smc_diag_dump() may be still reading smc->clcsock, therefore this could cause a use-after-free as reported by syzbot. Reported-and-tested-by: syzbot+fbd1e5476e4c94c7b34e@syzkaller.appspotmail.com Fixes: 51f1de79ad8e ("net/smc: replace sock_put worker by socket refcounting") Cc: Ursula Braun Signed-off-by: Cong Wang Reported-by: syzbot+0bf2e01269f1274b4b03@syzkaller.appspotmail.com Reported-by: syzbot+e3132895630f957306bc@syzkaller.appspotmail.com Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- diff --git a/net/smc/af_smc.c b/net/smc/af_smc.c index 2b8f952906273..e6e506b2db99e 100644 --- a/net/smc/af_smc.c +++ b/net/smc/af_smc.c @@ -144,6 +144,9 @@ static int smc_release(struct socket *sock) sock_set_flag(sk, SOCK_DEAD); sk->sk_shutdown |= SHUTDOWN_MASK; } + + sk->sk_prot->unhash(sk); + if (smc->clcsock) { if (smc->use_fallback && sk->sk_state == SMC_LISTEN) { /* wake up clcsock accept */ @@ -168,7 +171,6 @@ static int smc_release(struct socket *sock) smc_conn_free(&smc->conn); release_sock(sk); - sk->sk_prot->unhash(sk); sock_put(sk); /* final sock_put */ out: return rc;