| 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-2021-47099: veth: ensure skb entering GRO are not cloned. |
| |
| Description |
| =========== |
| |
| In the Linux kernel, the following vulnerability has been resolved: |
| |
| veth: ensure skb entering GRO are not cloned. |
| |
| After commit d3256efd8e8b ("veth: allow enabling NAPI even without XDP"), |
| if GRO is enabled on a veth device and TSO is disabled on the peer |
| device, TCP skbs will go through the NAPI callback. If there is no XDP |
| program attached, the veth code does not perform any share check, and |
| shared/cloned skbs could enter the GRO engine. |
| |
| Ignat reported a BUG triggered later-on due to the above condition: |
| |
| [ 53.970529][ C1] kernel BUG at net/core/skbuff.c:3574! |
| [ 53.981755][ C1] invalid opcode: 0000 [#1] PREEMPT SMP KASAN PTI |
| [ 53.982634][ C1] CPU: 1 PID: 19 Comm: ksoftirqd/1 Not tainted 5.16.0-rc5+ #25 |
| [ 53.982634][ C1] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015 |
| [ 53.982634][ C1] RIP: 0010:skb_shift+0x13ef/0x23b0 |
| [ 53.982634][ C1] Code: ea 03 0f b6 04 02 48 89 fa 83 e2 07 38 d0 |
| 7f 08 84 c0 0f 85 41 0c 00 00 41 80 7f 02 00 4d 8d b5 d0 00 00 00 0f |
| 85 74 f5 ff ff <0f> 0b 4d 8d 77 20 be 04 00 00 00 4c 89 44 24 78 4c 89 |
| f7 4c 89 8c |
| [ 53.982634][ C1] RSP: 0018:ffff8881008f7008 EFLAGS: 00010246 |
| [ 53.982634][ C1] RAX: 0000000000000000 RBX: ffff8881180b4c80 RCX: 0000000000000000 |
| [ 53.982634][ C1] RDX: 0000000000000002 RSI: ffff8881180b4d3c RDI: ffff88810bc9cac2 |
| [ 53.982634][ C1] RBP: ffff8881008f70b8 R08: ffff8881180b4cf4 R09: ffff8881180b4cf0 |
| [ 53.982634][ C1] R10: ffffed1022999e5c R11: 0000000000000002 R12: 0000000000000590 |
| [ 53.982634][ C1] R13: ffff88810f940c80 R14: ffff88810f940d50 R15: ffff88810bc9cac0 |
| [ 53.982634][ C1] FS: 0000000000000000(0000) GS:ffff888235880000(0000) knlGS:0000000000000000 |
| [ 53.982634][ C1] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 |
| [ 53.982634][ C1] CR2: 00007ff5f9b86680 CR3: 0000000108ce8004 CR4: 0000000000170ee0 |
| [ 53.982634][ C1] Call Trace: |
| [ 53.982634][ C1] <TASK> |
| [ 53.982634][ C1] tcp_sacktag_walk+0xaba/0x18e0 |
| [ 53.982634][ C1] tcp_sacktag_write_queue+0xe7b/0x3460 |
| [ 53.982634][ C1] tcp_ack+0x2666/0x54b0 |
| [ 53.982634][ C1] tcp_rcv_established+0x4d9/0x20f0 |
| [ 53.982634][ C1] tcp_v4_do_rcv+0x551/0x810 |
| [ 53.982634][ C1] tcp_v4_rcv+0x22ed/0x2ed0 |
| [ 53.982634][ C1] ip_protocol_deliver_rcu+0x96/0xaf0 |
| [ 53.982634][ C1] ip_local_deliver_finish+0x1e0/0x2f0 |
| [ 53.982634][ C1] ip_sublist_rcv_finish+0x211/0x440 |
| [ 53.982634][ C1] ip_list_rcv_finish.constprop.0+0x424/0x660 |
| [ 53.982634][ C1] ip_list_rcv+0x2c8/0x410 |
| [ 53.982634][ C1] __netif_receive_skb_list_core+0x65c/0x910 |
| [ 53.982634][ C1] netif_receive_skb_list_internal+0x5f9/0xcb0 |
| [ 53.982634][ C1] napi_complete_done+0x188/0x6e0 |
| [ 53.982634][ C1] gro_cell_poll+0x10c/0x1d0 |
| [ 53.982634][ C1] __napi_poll+0xa1/0x530 |
| [ 53.982634][ C1] net_rx_action+0x567/0x1270 |
| [ 53.982634][ C1] __do_softirq+0x28a/0x9ba |
| [ 53.982634][ C1] run_ksoftirqd+0x32/0x60 |
| [ 53.982634][ C1] smpboot_thread_fn+0x559/0x8c0 |
| [ 53.982634][ C1] kthread+0x3b9/0x490 |
| [ 53.982634][ C1] ret_from_fork+0x22/0x30 |
| [ 53.982634][ C1] </TASK> |
| |
| Address the issue by skipping the GRO stage for shared or cloned skbs. |
| To reduce the chance of OoO, try to unclone the skbs before giving up. |
| |
| v1 -> v2: |
| - use avoid skb_copy and fallback to netif_receive_skb - Eric |
| |
| The Linux kernel CVE team has assigned CVE-2021-47099 to this issue. |
| |
| |
| Affected and fixed versions |
| =========================== |
| |
| Issue introduced in 5.13 with commit d3256efd8e8b234a6251e4d4580bd2c3c31fdc4c and fixed in 5.15.12 with commit d2269ae48598e05b59ec9ea9e6e44fd33941130d |
| Issue introduced in 5.13 with commit d3256efd8e8b234a6251e4d4580bd2c3c31fdc4c and fixed in 5.16 with commit 9695b7de5b4760ed22132aca919570c0190cb0ce |
| |
| 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-2021-47099 |
| 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: |
| drivers/net/veth.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/d2269ae48598e05b59ec9ea9e6e44fd33941130d |
| https://git.kernel.org/stable/c/9695b7de5b4760ed22132aca919570c0190cb0ce |
