From: Wen Gu guwen@linux.alibaba.com
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 guwen@linux.alibaba.com Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- net/smc/af_smc.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-)
--- a/net/smc/af_smc.c +++ b/net/smc/af_smc.c @@ -667,14 +667,17 @@ static void smc_fback_error_report(struc 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->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 */