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authorJann Horn <jannh@google.com>2018-06-25 17:22:00 +0200
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2018-07-11 15:42:26 +0200
commitea2db4202d34c553b91ff81551335dc2d488f76e (patch)
treed0d45b28c4e32a37ae85895b324c0f85d3c65035
parent1e4c8faf6409f4562213cad75013653f548c1561 (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.c9
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;