[34-longterm 162/247] netfilter: nf_log: avoid oops in (un)bind with invalid nfproto values

Paul Gortmaker
2011-06-23T18:01:16Z

From: Jan Engelhardt <jengelh@medozas.de>

-------------------
This is a commit scheduled for the next v2.6.34 longterm release.
If you see a problem with using this for longterm, please comment.
-------------------

commit 9ef0298a8e5730d9a46d640014c727f3b4152870 upstream.

Like many other places, we have to check that the array index is
within allowed limits, or otherwise, a kernel oops and other nastiness
can ensue when we access memory beyond the end of the array.

[ 5954.115381] BUG: unable to handle kernel paging request at 0000004000000000
[ 5954.120014] IP: __find_logger+0x6f/0xa0
[ 5954.123979] nf_log_bind_pf+0x2b/0x70
[ 5954.123979] nfulnl_recv_config+0xc0/0x4a0 [nfnetlink_log]
[ 5954.123979] nfnetlink_rcv_msg+0x12c/0x1b0 [nfnetlink]
...

The problem goes back to v2.6.30-rc1~1372~1342~31 where nf_log_bind
was decoupled from nf_log_register.

Reported-by: Miguel Di Ciurcio Filho <miguel.filho@gmail.com>,
via irc.freenode.net/#netfilter
Signed-off-by: Jan Engelhardt <jengelh@medozas.de>
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
---
net/netfilter/nf_log.c | 4 ++++
1 files changed, 4 insertions(+), 0 deletions(-)

diff --git a/net/netfilter/nf_log.c b/net/netfilter/nf_log.c
index 015725a..eda826b 100644
--- a/net/netfilter/nf_log.c
+++ b/net/netfilter/nf_log.c
@@ -83,6 +83,8 @@ EXPORT_SYMBOL(nf_log_unregister);

int nf_log_bind_pf(u_int8_t pf, const struct nf_logger *logger)
{
+ if (pf >= ARRAY_SIZE(nf_loggers))
+ return -EINVAL;
mutex_lock(&nf_log_mutex);
if (__find_logger(pf, logger->name) == NULL) {
mutex_unlock(&nf_log_mutex);
@@ -96,6 +98,8 @@ EXPORT_SYMBOL(nf_log_bind_pf);

void nf_log_unbind_pf(u_int8_t pf)
{
+ if (pf >= ARRAY_SIZE(nf_loggers))
+ return;
mutex_lock(&nf_log_mutex);
rcu_assign_pointer(nf_loggers[pf], NULL);
mutex_unlock(&nf_log_mutex);
--
1.7.4.4