[linux] 06/07: l2tp: fix racy SOCK_ZAPPED flag check in l2tp_ip{, 6}_bind() (CVE-2016-10200)
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debian-kernel at lists.debian.org
Tue Mar 14 14:16:59 UTC 2017
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in repository linux.
commit 71b7929cd2a3d5a000b4ee60616a5336b4105846
Author: Ben Hutchings <ben at decadent.org.uk>
Date: Tue Mar 14 01:28:43 2017 +0000
l2tp: fix racy SOCK_ZAPPED flag check in l2tp_ip{,6}_bind() (CVE-2016-10200)
---
debian/changelog | 1 +
...cy-sock_zapped-flag-check-in-l2tp_ip-6-_b.patch | 161 +++++++++++++++++++++
debian/patches/series | 1 +
3 files changed, 163 insertions(+)
diff --git a/debian/changelog b/debian/changelog
index 3cadcdd..b5e427e 100644
--- a/debian/changelog
+++ b/debian/changelog
@@ -6,6 +6,7 @@ linux (3.16.39-1+deb8u3) UNRELEASED; urgency=medium
* mnt: Add a per mount namespace limit on the number of mounts (CVE-2016-6213)
* vfs: Commit to never having executables on proc and sysfs
* aio: mark AIO pseudo-fs noexec (CVE-2016-10044)
+ * l2tp: fix racy SOCK_ZAPPED flag check in l2tp_ip{,6}_bind() (CVE-2016-10200)
-- Ben Hutchings <ben at decadent.org.uk> Mon, 13 Mar 2017 23:29:39 +0000
diff --git a/debian/patches/bugfix/all/l2tp-fix-racy-sock_zapped-flag-check-in-l2tp_ip-6-_b.patch b/debian/patches/bugfix/all/l2tp-fix-racy-sock_zapped-flag-check-in-l2tp_ip-6-_b.patch
new file mode 100644
index 0000000..36fe2f2
--- /dev/null
+++ b/debian/patches/bugfix/all/l2tp-fix-racy-sock_zapped-flag-check-in-l2tp_ip-6-_b.patch
@@ -0,0 +1,161 @@
+From: Guillaume Nault <g.nault at alphalink.fr>
+Date: Fri, 18 Nov 2016 22:13:00 +0100
+Subject: l2tp: fix racy SOCK_ZAPPED flag check in l2tp_ip{,6}_bind()
+Origin: https://git.kernel.org/linus/32c231164b762dddefa13af5a0101032c70b50ef
+Bug-Debian-Security: https://security-tracker.debian.org/tracker/CVE-2016-10200
+
+Lock socket before checking the SOCK_ZAPPED flag in l2tp_ip6_bind().
+Without lock, a concurrent call could modify the socket flags between
+the sock_flag(sk, SOCK_ZAPPED) test and the lock_sock() call. This way,
+a socket could be inserted twice in l2tp_ip6_bind_table. Releasing it
+would then leave a stale pointer there, generating use-after-free
+errors when walking through the list or modifying adjacent entries.
+
+BUG: KASAN: use-after-free in l2tp_ip6_close+0x22e/0x290 at addr ffff8800081b0ed8
+Write of size 8 by task syz-executor/10987
+CPU: 0 PID: 10987 Comm: syz-executor Not tainted 4.8.0+ #39
+Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.8.2-0-g33fbe13 by qemu-project.org 04/01/2014
+ ffff880031d97838 ffffffff829f835b ffff88001b5a1640 ffff8800081b0ec0
+ ffff8800081b15a0 ffff8800081b6d20 ffff880031d97860 ffffffff8174d3cc
+ ffff880031d978f0 ffff8800081b0e80 ffff88001b5a1640 ffff880031d978e0
+Call Trace:
+ [<ffffffff829f835b>] dump_stack+0xb3/0x118 lib/dump_stack.c:15
+ [<ffffffff8174d3cc>] kasan_object_err+0x1c/0x70 mm/kasan/report.c:156
+ [< inline >] print_address_description mm/kasan/report.c:194
+ [<ffffffff8174d666>] kasan_report_error+0x1f6/0x4d0 mm/kasan/report.c:283
+ [< inline >] kasan_report mm/kasan/report.c:303
+ [<ffffffff8174db7e>] __asan_report_store8_noabort+0x3e/0x40 mm/kasan/report.c:329
+ [< inline >] __write_once_size ./include/linux/compiler.h:249
+ [< inline >] __hlist_del ./include/linux/list.h:622
+ [< inline >] hlist_del_init ./include/linux/list.h:637
+ [<ffffffff8579047e>] l2tp_ip6_close+0x22e/0x290 net/l2tp/l2tp_ip6.c:239
+ [<ffffffff850b2dfd>] inet_release+0xed/0x1c0 net/ipv4/af_inet.c:415
+ [<ffffffff851dc5a0>] inet6_release+0x50/0x70 net/ipv6/af_inet6.c:422
+ [<ffffffff84c4581d>] sock_release+0x8d/0x1d0 net/socket.c:570
+ [<ffffffff84c45976>] sock_close+0x16/0x20 net/socket.c:1017
+ [<ffffffff817a108c>] __fput+0x28c/0x780 fs/file_table.c:208
+ [<ffffffff817a1605>] ____fput+0x15/0x20 fs/file_table.c:244
+ [<ffffffff813774f9>] task_work_run+0xf9/0x170
+ [<ffffffff81324aae>] do_exit+0x85e/0x2a00
+ [<ffffffff81326dc8>] do_group_exit+0x108/0x330
+ [<ffffffff81348cf7>] get_signal+0x617/0x17a0 kernel/signal.c:2307
+ [<ffffffff811b49af>] do_signal+0x7f/0x18f0
+ [<ffffffff810039bf>] exit_to_usermode_loop+0xbf/0x150 arch/x86/entry/common.c:156
+ [< inline >] prepare_exit_to_usermode arch/x86/entry/common.c:190
+ [<ffffffff81006060>] syscall_return_slowpath+0x1a0/0x1e0 arch/x86/entry/common.c:259
+ [<ffffffff85e4d726>] entry_SYSCALL_64_fastpath+0xc4/0xc6
+Object at ffff8800081b0ec0, in cache L2TP/IPv6 size: 1448
+Allocated:
+PID = 10987
+ [ 1116.897025] [<ffffffff811ddcb6>] save_stack_trace+0x16/0x20
+ [ 1116.897025] [<ffffffff8174c736>] save_stack+0x46/0xd0
+ [ 1116.897025] [<ffffffff8174c9ad>] kasan_kmalloc+0xad/0xe0
+ [ 1116.897025] [<ffffffff8174cee2>] kasan_slab_alloc+0x12/0x20
+ [ 1116.897025] [< inline >] slab_post_alloc_hook mm/slab.h:417
+ [ 1116.897025] [< inline >] slab_alloc_node mm/slub.c:2708
+ [ 1116.897025] [< inline >] slab_alloc mm/slub.c:2716
+ [ 1116.897025] [<ffffffff817476a8>] kmem_cache_alloc+0xc8/0x2b0 mm/slub.c:2721
+ [ 1116.897025] [<ffffffff84c4f6a9>] sk_prot_alloc+0x69/0x2b0 net/core/sock.c:1326
+ [ 1116.897025] [<ffffffff84c58ac8>] sk_alloc+0x38/0xae0 net/core/sock.c:1388
+ [ 1116.897025] [<ffffffff851ddf67>] inet6_create+0x2d7/0x1000 net/ipv6/af_inet6.c:182
+ [ 1116.897025] [<ffffffff84c4af7b>] __sock_create+0x37b/0x640 net/socket.c:1153
+ [ 1116.897025] [< inline >] sock_create net/socket.c:1193
+ [ 1116.897025] [< inline >] SYSC_socket net/socket.c:1223
+ [ 1116.897025] [<ffffffff84c4b46f>] SyS_socket+0xef/0x1b0 net/socket.c:1203
+ [ 1116.897025] [<ffffffff85e4d685>] entry_SYSCALL_64_fastpath+0x23/0xc6
+Freed:
+PID = 10987
+ [ 1116.897025] [<ffffffff811ddcb6>] save_stack_trace+0x16/0x20
+ [ 1116.897025] [<ffffffff8174c736>] save_stack+0x46/0xd0
+ [ 1116.897025] [<ffffffff8174cf61>] kasan_slab_free+0x71/0xb0
+ [ 1116.897025] [< inline >] slab_free_hook mm/slub.c:1352
+ [ 1116.897025] [< inline >] slab_free_freelist_hook mm/slub.c:1374
+ [ 1116.897025] [< inline >] slab_free mm/slub.c:2951
+ [ 1116.897025] [<ffffffff81748b28>] kmem_cache_free+0xc8/0x330 mm/slub.c:2973
+ [ 1116.897025] [< inline >] sk_prot_free net/core/sock.c:1369
+ [ 1116.897025] [<ffffffff84c541eb>] __sk_destruct+0x32b/0x4f0 net/core/sock.c:1444
+ [ 1116.897025] [<ffffffff84c5aca4>] sk_destruct+0x44/0x80 net/core/sock.c:1452
+ [ 1116.897025] [<ffffffff84c5ad33>] __sk_free+0x53/0x220 net/core/sock.c:1460
+ [ 1116.897025] [<ffffffff84c5af23>] sk_free+0x23/0x30 net/core/sock.c:1471
+ [ 1116.897025] [<ffffffff84c5cb6c>] sk_common_release+0x28c/0x3e0 ./include/net/sock.h:1589
+ [ 1116.897025] [<ffffffff8579044e>] l2tp_ip6_close+0x1fe/0x290 net/l2tp/l2tp_ip6.c:243
+ [ 1116.897025] [<ffffffff850b2dfd>] inet_release+0xed/0x1c0 net/ipv4/af_inet.c:415
+ [ 1116.897025] [<ffffffff851dc5a0>] inet6_release+0x50/0x70 net/ipv6/af_inet6.c:422
+ [ 1116.897025] [<ffffffff84c4581d>] sock_release+0x8d/0x1d0 net/socket.c:570
+ [ 1116.897025] [<ffffffff84c45976>] sock_close+0x16/0x20 net/socket.c:1017
+ [ 1116.897025] [<ffffffff817a108c>] __fput+0x28c/0x780 fs/file_table.c:208
+ [ 1116.897025] [<ffffffff817a1605>] ____fput+0x15/0x20 fs/file_table.c:244
+ [ 1116.897025] [<ffffffff813774f9>] task_work_run+0xf9/0x170
+ [ 1116.897025] [<ffffffff81324aae>] do_exit+0x85e/0x2a00
+ [ 1116.897025] [<ffffffff81326dc8>] do_group_exit+0x108/0x330
+ [ 1116.897025] [<ffffffff81348cf7>] get_signal+0x617/0x17a0 kernel/signal.c:2307
+ [ 1116.897025] [<ffffffff811b49af>] do_signal+0x7f/0x18f0
+ [ 1116.897025] [<ffffffff810039bf>] exit_to_usermode_loop+0xbf/0x150 arch/x86/entry/common.c:156
+ [ 1116.897025] [< inline >] prepare_exit_to_usermode arch/x86/entry/common.c:190
+ [ 1116.897025] [<ffffffff81006060>] syscall_return_slowpath+0x1a0/0x1e0 arch/x86/entry/common.c:259
+ [ 1116.897025] [<ffffffff85e4d726>] entry_SYSCALL_64_fastpath+0xc4/0xc6
+Memory state around the buggy address:
+ ffff8800081b0d80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
+ ffff8800081b0e00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
+>ffff8800081b0e80: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb
+ ^
+ ffff8800081b0f00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
+ ffff8800081b0f80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
+
+==================================================================
+
+The same issue exists with l2tp_ip_bind() and l2tp_ip_bind_table.
+
+Fixes: c51ce49735c1 ("l2tp: fix oops in L2TP IP sockets for connect() AF_UNSPEC case")
+Reported-by: Baozeng Ding <sploving1 at gmail.com>
+Reported-by: Andrey Konovalov <andreyknvl at google.com>
+Tested-by: Baozeng Ding <sploving1 at gmail.com>
+Signed-off-by: Guillaume Nault <g.nault at alphalink.fr>
+Signed-off-by: David S. Miller <davem at davemloft.net>
+---
+ net/l2tp/l2tp_ip.c | 5 +++--
+ net/l2tp/l2tp_ip6.c | 5 +++--
+ 2 files changed, 6 insertions(+), 4 deletions(-)
+
+--- a/net/l2tp/l2tp_ip.c
++++ b/net/l2tp/l2tp_ip.c
+@@ -251,8 +251,6 @@ static int l2tp_ip_bind(struct sock *sk,
+ int ret;
+ int chk_addr_ret;
+
+- if (!sock_flag(sk, SOCK_ZAPPED))
+- return -EINVAL;
+ if (addr_len < sizeof(struct sockaddr_l2tpip))
+ return -EINVAL;
+ if (addr->l2tp_family != AF_INET)
+@@ -267,6 +265,9 @@ static int l2tp_ip_bind(struct sock *sk,
+ read_unlock_bh(&l2tp_ip_lock);
+
+ lock_sock(sk);
++ if (!sock_flag(sk, SOCK_ZAPPED))
++ goto out;
++
+ if (sk->sk_state != TCP_CLOSE || addr_len < sizeof(struct sockaddr_l2tpip))
+ goto out;
+
+--- a/net/l2tp/l2tp_ip6.c
++++ b/net/l2tp/l2tp_ip6.c
+@@ -266,8 +266,6 @@ static int l2tp_ip6_bind(struct sock *sk
+ int addr_type;
+ int err;
+
+- if (!sock_flag(sk, SOCK_ZAPPED))
+- return -EINVAL;
+ if (addr->l2tp_family != AF_INET6)
+ return -EINVAL;
+ if (addr_len < sizeof(*addr))
+@@ -293,6 +291,9 @@ static int l2tp_ip6_bind(struct sock *sk
+ lock_sock(sk);
+
+ err = -EINVAL;
++ if (!sock_flag(sk, SOCK_ZAPPED))
++ goto out_unlock;
++
+ if (sk->sk_state != TCP_CLOSE)
+ goto out_unlock;
+
diff --git a/debian/patches/series b/debian/patches/series
index 3c99601..1b3f967 100644
--- a/debian/patches/series
+++ b/debian/patches/series
@@ -709,6 +709,7 @@ bugfix/all/mbcache-reschedule-before-restarting-iteration-in-mb_cache_entry_allo
bugfix/all/mnt-add-a-per-mount-namespace-limit-on-the-number-of.patch
bugfix/all/vfs-commit-to-never-having-exectuables-on-proc-and-s.patch
bugfix/all/aio-mark-aio-pseudo-fs-noexec.patch
+bugfix/all/l2tp-fix-racy-sock_zapped-flag-check-in-l2tp_ip-6-_b.patch
# Fix ABI changes
debian/of-fix-abi-changes.patch
--
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