diff --git a/debian/changelog b/debian/changelog index 7fc722836..b529baaee 100644 --- a/debian/changelog +++ b/debian/changelog @@ -57,6 +57,7 @@ linux (4.3.4-1) UNRELEASED; urgency=medium [ Salvatore Bonaccorso ] * tcp: fix zero cwnd in tcp_cwnd_reduction (CVE-2016-2070) + * netfilter: nf_nat_redirect: add missing NULL pointer check (CVE-2015-8787) -- Ben Hutchings Sat, 23 Jan 2016 11:51:46 +0000 diff --git a/debian/patches/bugfix/all/netfilter-nf_nat_redirect-add-missing-NULL-pointer-c.patch b/debian/patches/bugfix/all/netfilter-nf_nat_redirect-add-missing-NULL-pointer-c.patch new file mode 100644 index 000000000..fd17d1e98 --- /dev/null +++ b/debian/patches/bugfix/all/netfilter-nf_nat_redirect-add-missing-NULL-pointer-c.patch @@ -0,0 +1,81 @@ +From: Munehisa Kamata +Date: Mon, 26 Oct 2015 19:10:52 -0700 +Subject: netfilter: nf_nat_redirect: add missing NULL pointer check +Origin: https://git.kernel.org/linus/94f9cd81436c85d8c3a318ba92e236ede73752fc + +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: [] 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: + + [] redirect_tg4+0x15/0x20 [xt_REDIRECT] + [] ipt_do_table+0x2b9/0x5e1 [ip_tables] + [] iptable_nat_do_chain+0x25/0x30 [iptable_nat] + [] nf_nat_ipv4_fn+0x13d/0x1f0 [nf_nat_ipv4] + [] ? iptable_nat_ipv4_fn+0x20/0x20 [iptable_nat] + [] nf_nat_ipv4_in+0x2e/0x90 [nf_nat_ipv4] + [] iptable_nat_ipv4_in+0x15/0x20 [iptable_nat] + [] nf_iterate+0x57/0x80 + [] nf_hook_slow+0x97/0x100 + [] 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 +Signed-off-by: Pablo Neira Ayuso +--- + net/netfilter/nf_nat_redirect.c | 2 +- + 1 file changed, 1 insertion(+), 1 deletion(-) + +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; + } +-- +2.7.0 + diff --git a/debian/patches/series b/debian/patches/series index 3e8a2fb29..a202989e4 100644 --- a/debian/patches/series +++ b/debian/patches/series @@ -143,3 +143,4 @@ bugfix/all/bcache-change-refill_dirty-to-always-scan-entire-dis.patch bugfix/all/fuse-break-infinite-loop-in-fuse_fill_write_pages.patch bugfix/all/tcp-fix-zero-cwnd-in-tcp_cwnd_reduction.patch bugfix/all/scsi-fix-crashes-in-sd-and-sr-runtime-pm.patch +bugfix/all/netfilter-nf_nat_redirect-add-missing-NULL-pointer-c.patch