diff options
| author | Jann Horn <jannh@google.com> | 2018-06-25 17:22:00 +0200 |
|---|---|---|
| committer | Pablo Neira Ayuso <pablo@netfilter.org> | 2018-06-26 16:48:40 +0200 |
| commit | ce00bf07cc95a57cd20b208e02b3c2604e532ae8 (patch) | |
| tree | 84e98d9b5c39e5655d98abd3fc4e419f89e4969f /net/netfilter | |
| parent | dffd22aed2aa1e804bccf19b30a421e89ee2ae61 (diff) | |
netfilter: nf_log: don't hold nf_log_mutex during user access
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>
Diffstat (limited to 'net/netfilter')
| -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 2c47f9ec3511..a61d6df6e5f6 100644 --- a/net/netfilter/nf_log.c +++ b/net/netfilter/nf_log.c @@ -446,14 +446,17 @@ 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; |