4.20-stable review patch. If anyone has any objections, please let me know.
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From: Cong Wang xiyou.wangcong@gmail.com
[ 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 ubraun@linux.ibm.com Signed-off-by: Cong Wang xiyou.wangcong@gmail.com Reported-by: syzbot+0bf2e01269f1274b4b03@syzkaller.appspotmail.com Reported-by: syzbot+e3132895630f957306bc@syzkaller.appspotmail.com Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- net/smc/af_smc.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)
--- a/net/smc/af_smc.c +++ b/net/smc/af_smc.c @@ -146,6 +146,9 @@ static int smc_release(struct socket *so 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 */ @@ -170,7 +173,6 @@ static int smc_release(struct socket *so smc_conn_free(&smc->conn); release_sock(sk);
- sk->sk_prot->unhash(sk); sock_put(sk); /* final sock_put */ out: return rc;