diff options
| author | Jann Horn <jannh@google.com> | 2018-06-25 17:22:00 +0200 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2018-07-11 15:42:26 +0200 |
| commit | ea2db4202d34c553b91ff81551335dc2d488f76e (patch) | |
| tree | d0d45b28c4e32a37ae85895b324c0f85d3c65035 | |
| parent | 1e4c8faf6409f4562213cad75013653f548c1561 (diff) | |
netfilter: nf_log: don't hold nf_log_mutex during user access
commit ce00bf07cc95a57cd20b208e02b3c2604e532ae8 upstream.
The old code would indefinitely block other users of nf_log_mutex if
a userspace access in proc_dostring() blocked e.g. due to a userfaultfd
region. Fix it by moving proc_dostring() out of the locked region.
This is a followup to commit 266d07cb1c9a ("netfilter: nf_log: fix
sleeping function called from invalid context"), which changed this code
from using rcu_read_lock() to taking nf_log_mutex.
Fixes: 266d07cb1c9a ("netfilter: nf_log: fix sleeping function calle[...]")
Signed-off-by: Jann Horn <jannh@google.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | net/netfilter/nf_log.c | 9 |
1 files changed, 6 insertions, 3 deletions
diff --git a/net/netfilter/nf_log.c b/net/netfilter/nf_log.c index cfe93c2227c5..ee15f31b4999 100644 --- a/net/netfilter/nf_log.c +++ b/net/netfilter/nf_log.c @@ -387,14 +387,17 @@ static int nf_log_proc_dostring(struct ctl_table *table, int write, rcu_assign_pointer(net->nf.nf_loggers[tindex], logger); mutex_unlock(&nf_log_mutex); } else { + struct ctl_table tmp = *table; + + tmp.data = buf; mutex_lock(&nf_log_mutex); logger = nft_log_dereference(net->nf.nf_loggers[tindex]); if (!logger) - table->data = "NONE"; + strlcpy(buf, "NONE", sizeof(buf)); else - table->data = logger->name; - r = proc_dostring(table, write, buffer, lenp, ppos); + strlcpy(buf, logger->name, sizeof(buf)); mutex_unlock(&nf_log_mutex); + r = proc_dostring(&tmp, write, buffer, lenp, ppos); } return r; |