| From bippy-5f407fcff5a0 Mon Sep 17 00:00:00 2001 |
| From: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| To: <linux-cve-announce@vger.kernel.org> |
| Reply-to: <cve@kernel.org>, <linux-kernel@vger.kernel.org> |
| Subject: CVE-2021-47572: net: nexthop: fix null pointer dereference when IPv6 is not enabled |
| |
| Description |
| =========== |
| |
| In the Linux kernel, the following vulnerability has been resolved: |
| |
| net: nexthop: fix null pointer dereference when IPv6 is not enabled |
| |
| When we try to add an IPv6 nexthop and IPv6 is not enabled |
| (!CONFIG_IPV6) we'll hit a NULL pointer dereference[1] in the error path |
| of nh_create_ipv6() due to calling ipv6_stub->fib6_nh_release. The bug |
| has been present since the beginning of IPv6 nexthop gateway support. |
| Commit 1aefd3de7bc6 ("ipv6: Add fib6_nh_init and release to stubs") tells |
| us that only fib6_nh_init has a dummy stub because fib6_nh_release should |
| not be called if fib6_nh_init returns an error, but the commit below added |
| a call to ipv6_stub->fib6_nh_release in its error path. To fix it return |
| the dummy stub's -EAFNOSUPPORT error directly without calling |
| ipv6_stub->fib6_nh_release in nh_create_ipv6()'s error path. |
| |
| [1] |
| Output is a bit truncated, but it clearly shows the error. |
| BUG: kernel NULL pointer dereference, address: 000000000000000000 |
| #PF: supervisor instruction fetch in kernel modede |
| #PF: error_code(0x0010) - not-present pagege |
| PGD 0 P4D 0 |
| Oops: 0010 [#1] PREEMPT SMP NOPTI |
| CPU: 4 PID: 638 Comm: ip Kdump: loaded Not tainted 5.16.0-rc1+ #446 |
| Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.14.0-4.fc34 04/01/2014 |
| RIP: 0010:0x0 |
| Code: Unable to access opcode bytes at RIP 0xffffffffffffffd6. |
| RSP: 0018:ffff888109f5b8f0 EFLAGS: 00010286^Ac |
| RAX: 0000000000000000 RBX: ffff888109f5ba28 RCX: 0000000000000000 |
| RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffff8881008a2860 |
| RBP: ffff888109f5b9d8 R08: 0000000000000000 R09: 0000000000000000 |
| R10: ffff888109f5b978 R11: ffff888109f5b948 R12: 00000000ffffff9f |
| R13: ffff8881008a2a80 R14: ffff8881008a2860 R15: ffff8881008a2840 |
| FS: 00007f98de70f100(0000) GS:ffff88822bf00000(0000) knlGS:0000000000000000 |
| CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 |
| CR2: ffffffffffffffd6 CR3: 0000000100efc000 CR4: 00000000000006e0 |
| Call Trace: |
| <TASK> |
| nh_create_ipv6+0xed/0x10c |
| rtm_new_nexthop+0x6d7/0x13f3 |
| ? check_preemption_disabled+0x3d/0xf2 |
| ? lock_is_held_type+0xbe/0xfd |
| rtnetlink_rcv_msg+0x23f/0x26a |
| ? check_preemption_disabled+0x3d/0xf2 |
| ? rtnl_calcit.isra.0+0x147/0x147 |
| netlink_rcv_skb+0x61/0xb2 |
| netlink_unicast+0x100/0x187 |
| netlink_sendmsg+0x37f/0x3a0 |
| ? netlink_unicast+0x187/0x187 |
| sock_sendmsg_nosec+0x67/0x9b |
| ____sys_sendmsg+0x19d/0x1f9 |
| ? copy_msghdr_from_user+0x4c/0x5e |
| ? rcu_read_lock_any_held+0x2a/0x78 |
| ___sys_sendmsg+0x6c/0x8c |
| ? asm_sysvec_apic_timer_interrupt+0x12/0x20 |
| ? lockdep_hardirqs_on+0xd9/0x102 |
| ? sockfd_lookup_light+0x69/0x99 |
| __sys_sendmsg+0x50/0x6e |
| do_syscall_64+0xcb/0xf2 |
| entry_SYSCALL_64_after_hwframe+0x44/0xae |
| RIP: 0033:0x7f98dea28914 |
| Code: 00 f7 d8 64 89 02 48 c7 c0 ff ff ff ff eb b5 0f 1f 80 00 00 00 00 48 8d 05 e9 5d 0c 00 8b 00 85 c0 75 13 b8 2e 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 54 c3 0f 1f 00 41 54 41 89 d4 55 48 89 f5 53 |
| RSP: 002b:00007fff859f5e68 EFLAGS: 00000246 ORIG_RAX: 000000000000002e2e |
| RAX: ffffffffffffffda RBX: 00000000619cb810 RCX: 00007f98dea28914 |
| RDX: 0000000000000000 RSI: 00007fff859f5ed0 RDI: 0000000000000003 |
| RBP: 0000000000000000 R08: 0000000000000001 R09: 0000000000000008 |
| R10: fffffffffffffce6 R11: 0000000000000246 R12: 0000000000000001 |
| R13: 000055c0097ae520 R14: 000055c0097957fd R15: 00007fff859f63a0 |
| </TASK> |
| Modules linked in: bridge stp llc bonding virtio_net |
| |
| The Linux kernel CVE team has assigned CVE-2021-47572 to this issue. |
| |
| |
| Affected and fixed versions |
| =========================== |
| |
| Issue introduced in 5.3 with commit 53010f991a9f5e4ed2db705ddde6ff32709192a2 and fixed in 5.4.163 with commit 7b6f44856da5ba0b1aa61403eb9fddd272156503 |
| Issue introduced in 5.3 with commit 53010f991a9f5e4ed2db705ddde6ff32709192a2 and fixed in 5.10.83 with commit b70ff391deeec35cdd8a05f5f63f5fe28bc4f225 |
| Issue introduced in 5.3 with commit 53010f991a9f5e4ed2db705ddde6ff32709192a2 and fixed in 5.15.6 with commit 39509d76a9a3d02f379d52cb4b1449469c56c0e0 |
| Issue introduced in 5.3 with commit 53010f991a9f5e4ed2db705ddde6ff32709192a2 and fixed in 5.16 with commit 1c743127cc54b112b155f434756bd4b5fa565a99 |
| |
| Please see https://www.kernel.org for a full list of currently supported |
| kernel versions by the kernel community. |
| |
| Unaffected versions might change over time as fixes are backported to |
| older supported kernel versions. The official CVE entry at |
| https://cve.org/CVERecord/?id=CVE-2021-47572 |
| will be updated if fixes are backported, please check that for the most |
| up to date information about this issue. |
| |
| |
| Affected files |
| ============== |
| |
| The file(s) affected by this issue are: |
| net/ipv4/nexthop.c |
| |
| |
| Mitigation |
| ========== |
| |
| The Linux kernel CVE team recommends that you update to the latest |
| stable kernel version for this, and many other bugfixes. Individual |
| changes are never tested alone, but rather are part of a larger kernel |
| release. Cherry-picking individual commits is not recommended or |
| supported by the Linux kernel community at all. If however, updating to |
| the latest release is impossible, the individual changes to resolve this |
| issue can be found at these commits: |
| https://git.kernel.org/stable/c/7b6f44856da5ba0b1aa61403eb9fddd272156503 |
| https://git.kernel.org/stable/c/b70ff391deeec35cdd8a05f5f63f5fe28bc4f225 |
| https://git.kernel.org/stable/c/39509d76a9a3d02f379d52cb4b1449469c56c0e0 |
| https://git.kernel.org/stable/c/1c743127cc54b112b155f434756bd4b5fa565a99 |
