4.19-stable review patch. If anyone has any objections, please let me know.
------------------ From: Cong Wang <[email protected]> [ 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: [email protected] Fixes: 51f1de79ad8e ("net/smc: replace sock_put worker by socket refcounting") Cc: Ursula Braun <[email protected]> Signed-off-by: Cong Wang <[email protected]> Reported-by: [email protected] Reported-by: [email protected] Signed-off-by: David S. Miller <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]> --- 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 @@ -144,6 +144,9 @@ 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 */ @@ -168,7 +171,6 @@ 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;
