From f00b6c976ae0dfbd9b891175f713f59095d23842 Mon Sep 17 00:00:00 2001 From: Wen Gu Date: Wed, 9 Feb 2022 22:10:53 +0800 Subject: [PATCH] net/smc: Avoid overwriting the copies of clcsock callback functions commit 1de9770d121ee9294794cca0e0be8fbfa0134ee8 upstream. The callback functions of clcsock will be saved and replaced during the fallback. But if the fallback happens more than once, then the copies of these callback functions will be overwritten incorrectly, resulting in a loop call issue: clcsk->sk_error_report |- smc_fback_error_report() <------------------------------| |- smc_fback_forward_wakeup() | (loop) |- clcsock_callback() (incorrectly overwritten) | |- smc->clcsk_error_report() ------------------| So this patch fixes the issue by saving these function pointers only once in the fallback and avoiding overwriting. Reported-by: syzbot+4de3c0e8a263e1e499bc@syzkaller.appspotmail.com Fixes: 341adeec9ada ("net/smc: Forward wakeup to smc socket waitqueue after fallback") Link: https://lore.kernel.org/r/0000000000006d045e05d78776f6@google.com Signed-off-by: Wen Gu Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- 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 0f5c305c55c5a..10d2d81f93376 100644 --- a/net/smc/af_smc.c +++ b/net/smc/af_smc.c @@ -667,14 +667,17 @@ static void smc_fback_error_report(struct sock *clcsk) static int smc_switch_to_fallback(struct smc_sock *smc, int reason_code) { struct sock *clcsk; + int rc = 0; mutex_lock(&smc->clcsock_release_lock); if (!smc->clcsock) { - mutex_unlock(&smc->clcsock_release_lock); - return -EBADF; + rc = -EBADF; + goto out; } clcsk = smc->clcsock->sk; + if (smc->use_fallback) + goto out; smc->use_fallback = true; smc->fallback_rsn = reason_code; smc_stat_fallback(smc); @@ -702,8 +705,9 @@ static int smc_switch_to_fallback(struct smc_sock *smc, int reason_code) smc->clcsock->sk->sk_user_data = (void *)((uintptr_t)smc | SK_USER_DATA_NOCOPY); } +out: mutex_unlock(&smc->clcsock_release_lock); - return 0; + return rc; } /* fall back during connect */