| 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-2021-47590: mptcp: fix deadlock in __mptcp_push_pending() |
| |
| Description |
| =========== |
| |
| In the Linux kernel, the following vulnerability has been resolved: |
| |
| mptcp: fix deadlock in __mptcp_push_pending() |
| |
| __mptcp_push_pending() may call mptcp_flush_join_list() with subflow |
| socket lock held. If such call hits mptcp_sockopt_sync_all() then |
| subsequently __mptcp_sockopt_sync() could try to lock the subflow |
| socket for itself, causing a deadlock. |
| |
| sysrq: Show Blocked State |
| task:ss-server state:D stack: 0 pid: 938 ppid: 1 flags:0x00000000 |
| Call Trace: |
| <TASK> |
| __schedule+0x2d6/0x10c0 |
| ? __mod_memcg_state+0x4d/0x70 |
| ? csum_partial+0xd/0x20 |
| ? _raw_spin_lock_irqsave+0x26/0x50 |
| schedule+0x4e/0xc0 |
| __lock_sock+0x69/0x90 |
| ? do_wait_intr_irq+0xa0/0xa0 |
| __lock_sock_fast+0x35/0x50 |
| mptcp_sockopt_sync_all+0x38/0xc0 |
| __mptcp_push_pending+0x105/0x200 |
| mptcp_sendmsg+0x466/0x490 |
| sock_sendmsg+0x57/0x60 |
| __sys_sendto+0xf0/0x160 |
| ? do_wait_intr_irq+0xa0/0xa0 |
| ? fpregs_restore_userregs+0x12/0xd0 |
| __x64_sys_sendto+0x20/0x30 |
| do_syscall_64+0x38/0x90 |
| entry_SYSCALL_64_after_hwframe+0x44/0xae |
| RIP: 0033:0x7f9ba546c2d0 |
| RSP: 002b:00007ffdc3b762d8 EFLAGS: 00000246 ORIG_RAX: 000000000000002c |
| RAX: ffffffffffffffda RBX: 00007f9ba56c8060 RCX: 00007f9ba546c2d0 |
| RDX: 000000000000077a RSI: 0000000000e5e180 RDI: 0000000000000234 |
| RBP: 0000000000cc57f0 R08: 0000000000000000 R09: 0000000000000000 |
| R10: 0000000000000000 R11: 0000000000000246 R12: 00007f9ba56c8060 |
| R13: 0000000000b6ba60 R14: 0000000000cc7840 R15: 41d8685b1d7901b8 |
| </TASK> |
| |
| Fix the issue by using __mptcp_flush_join_list() instead of plain |
| mptcp_flush_join_list() inside __mptcp_push_pending(), as suggested by |
| Florian. The sockopt sync will be deferred to the workqueue. |
| |
| The Linux kernel CVE team has assigned CVE-2021-47590 to this issue. |
| |
| |
| Affected and fixed versions |
| =========================== |
| |
| Issue introduced in 5.13 with commit 1b3e7ede1365a24db1b4fd837e58a595f52fa4ad and fixed in 5.15.11 with commit 23311b92755ffa9087332d1bb8c71c0f6a10cc08 |
| Issue introduced in 5.13 with commit 1b3e7ede1365a24db1b4fd837e58a595f52fa4ad and fixed in 5.16 with commit 3d79e3756ca90f7a6087b77b62c1d9c0801e0820 |
| |
| 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-2021-47590 |
| 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/mptcp/protocol.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/23311b92755ffa9087332d1bb8c71c0f6a10cc08 |
| https://git.kernel.org/stable/c/3d79e3756ca90f7a6087b77b62c1d9c0801e0820 |
