| Message ID | 1448921453-13800-1-git-send-email-kamal@canonical.com |
|---|---|
| State | New |
| Headers | show |
diff --git a/net/netfilter/nf_nat_redirect.c b/net/netfilter/nf_nat_redirect.c index 97b75f9..d438698 100644 --- a/net/netfilter/nf_nat_redirect.c +++ b/net/netfilter/nf_nat_redirect.c @@ -55,7 +55,7 @@ nf_nat_redirect_ipv4(struct sk_buff *skb, rcu_read_lock(); indev = __in_dev_get_rcu(skb->dev); - if (indev != NULL) { + if (indev && indev->ifa_list) { ifa = indev->ifa_list; newdst = ifa->ifa_local; }
This is a note to let you know that I have just added a patch titled netfilter: nf_nat_redirect: add missing NULL pointer check to the linux-3.19.y-queue branch of the 3.19.y-ckt extended stable tree which can be found at: http://kernel.ubuntu.com/git/ubuntu/linux.git/log/?h=linux-3.19.y-queue This patch is scheduled to be released in version 3.19.8-ckt11. If you, or anyone else, feels it should not be added to this tree, please reply to this email. For more information about the 3.19.y-ckt tree, see https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable Thanks. -Kamal ------ From 78d999d1be8dc60d0f62382330434b341cc8343c Mon Sep 17 00:00:00 2001 From: Munehisa Kamata <kamatam@amazon.com> Date: Mon, 26 Oct 2015 19:10:52 -0700 Subject: netfilter: nf_nat_redirect: add missing NULL pointer check commit 94f9cd81436c85d8c3a318ba92e236ede73752fc upstream. Commit 8b13eddfdf04cbfa561725cfc42d6868fe896f56 ("netfilter: refactor NAT redirect IPv4 to use it from nf_tables") has introduced a trivial logic change which can result in the following crash. BUG: unable to handle kernel NULL pointer dereference at 0000000000000030 IP: [<ffffffffa033002d>] nf_nat_redirect_ipv4+0x2d/0xa0 [nf_nat_redirect] PGD 3ba662067 PUD 3ba661067 PMD 0 Oops: 0000 [#1] SMP Modules linked in: ipv6(E) xt_REDIRECT(E) nf_nat_redirect(E) xt_tcpudp(E) iptable_nat(E) nf_conntrack_ipv4(E) nf_defrag_ipv4(E) nf_nat_ipv4(E) nf_nat(E) nf_conntrack(E) ip_tables(E) x_tables(E) binfmt_misc(E) xfs(E) libcrc32c(E) evbug(E) evdev(E) psmouse(E) i2c_piix4(E) i2c_core(E) acpi_cpufreq(E) button(E) ext4(E) crc16(E) jbd2(E) mbcache(E) dm_mirror(E) dm_region_hash(E) dm_log(E) dm_mod(E) CPU: 0 PID: 2536 Comm: ip Tainted: G E 4.1.7-15.23.amzn1.x86_64 #1 Hardware name: Xen HVM domU, BIOS 4.2.amazon 05/06/2015 task: ffff8800eb438000 ti: ffff8803ba664000 task.ti: ffff8803ba664000 [...] Call Trace: <IRQ> [<ffffffffa0334065>] redirect_tg4+0x15/0x20 [xt_REDIRECT] [<ffffffffa02e2e99>] ipt_do_table+0x2b9/0x5e1 [ip_tables] [<ffffffffa0328045>] iptable_nat_do_chain+0x25/0x30 [iptable_nat] [<ffffffffa031777d>] nf_nat_ipv4_fn+0x13d/0x1f0 [nf_nat_ipv4] [<ffffffffa0328020>] ? iptable_nat_ipv4_fn+0x20/0x20 [iptable_nat] [<ffffffffa031785e>] nf_nat_ipv4_in+0x2e/0x90 [nf_nat_ipv4] [<ffffffffa03280a5>] iptable_nat_ipv4_in+0x15/0x20 [iptable_nat] [<ffffffff81449137>] nf_iterate+0x57/0x80 [<ffffffff814491f7>] nf_hook_slow+0x97/0x100 [<ffffffff814504d4>] ip_rcv+0x314/0x400 unsigned int nf_nat_redirect_ipv4(struct sk_buff *skb, ... { ... rcu_read_lock(); indev = __in_dev_get_rcu(skb->dev); if (indev != NULL) { ifa = indev->ifa_list; newdst = ifa->ifa_local; <--- } rcu_read_unlock(); ... } Before the commit, 'ifa' had been always checked before access. After the commit, however, it could be accessed even if it's NULL. Interestingly, this was once fixed in 2003. http://marc.info/?l=netfilter-devel&m=106668497403047&w=2 In addition to the original one, we have seen the crash when packets that need to be redirected somehow arrive on an interface which hasn't been yet fully configured. This change just reverts the logic to the old behavior to avoid the crash. Fixes: 8b13eddfdf04 ("netfilter: refactor NAT redirect IPv4 to use it from nf_tables") Signed-off-by: Munehisa Kamata <kamatam@amazon.com> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org> Signed-off-by: Kamal Mostafa <kamal@canonical.com> --- net/netfilter/nf_nat_redirect.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) -- 1.9.1