| 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-2024-58088: bpf: Fix deadlock when freeing cgroup storage |
| |
| Description |
| =========== |
| |
| In the Linux kernel, the following vulnerability has been resolved: |
| |
| bpf: Fix deadlock when freeing cgroup storage |
| |
| The following commit |
| bc235cdb423a ("bpf: Prevent deadlock from recursive bpf_task_storage_[get|delete]") |
| first introduced deadlock prevention for fentry/fexit programs attaching |
| on bpf_task_storage helpers. That commit also employed the logic in map |
| free path in its v6 version. |
| |
| Later bpf_cgrp_storage was first introduced in |
| c4bcfb38a95e ("bpf: Implement cgroup storage available to non-cgroup-attached bpf progs") |
| which faces the same issue as bpf_task_storage, instead of its busy |
| counter, NULL was passed to bpf_local_storage_map_free() which opened |
| a window to cause deadlock: |
| |
| <TASK> |
| (acquiring local_storage->lock) |
| _raw_spin_lock_irqsave+0x3d/0x50 |
| bpf_local_storage_update+0xd1/0x460 |
| bpf_cgrp_storage_get+0x109/0x130 |
| bpf_prog_a4d4a370ba857314_cgrp_ptr+0x139/0x170 |
| ? __bpf_prog_enter_recur+0x16/0x80 |
| bpf_trampoline_6442485186+0x43/0xa4 |
| cgroup_storage_ptr+0x9/0x20 |
| (holding local_storage->lock) |
| bpf_selem_unlink_storage_nolock.constprop.0+0x135/0x160 |
| bpf_selem_unlink_storage+0x6f/0x110 |
| bpf_local_storage_map_free+0xa2/0x110 |
| bpf_map_free_deferred+0x5b/0x90 |
| process_one_work+0x17c/0x390 |
| worker_thread+0x251/0x360 |
| kthread+0xd2/0x100 |
| ret_from_fork+0x34/0x50 |
| ret_from_fork_asm+0x1a/0x30 |
| </TASK> |
| |
| Progs: |
| - A: SEC("fentry/cgroup_storage_ptr") |
| - cgid (BPF_MAP_TYPE_HASH) |
| Record the id of the cgroup the current task belonging |
| to in this hash map, using the address of the cgroup |
| as the map key. |
| - cgrpa (BPF_MAP_TYPE_CGRP_STORAGE) |
| If current task is a kworker, lookup the above hash |
| map using function parameter @owner as the key to get |
| its corresponding cgroup id which is then used to get |
| a trusted pointer to the cgroup through |
| bpf_cgroup_from_id(). This trusted pointer can then |
| be passed to bpf_cgrp_storage_get() to finally trigger |
| the deadlock issue. |
| - B: SEC("tp_btf/sys_enter") |
| - cgrpb (BPF_MAP_TYPE_CGRP_STORAGE) |
| The only purpose of this prog is to fill Prog A's |
| hash map by calling bpf_cgrp_storage_get() for as |
| many userspace tasks as possible. |
| |
| Steps to reproduce: |
| - Run A; |
| - while (true) { Run B; Destroy B; } |
| |
| Fix this issue by passing its busy counter to the free procedure so |
| it can be properly incremented before storage/smap locking. |
| |
| The Linux kernel CVE team has assigned CVE-2024-58088 to this issue. |
| |
| |
| Affected and fixed versions |
| =========================== |
| |
| Issue introduced in 6.2 with commit c4bcfb38a95edb1021a53f2d0356a78120ecfbe4 and fixed in 6.6.80 with commit 6ecb9fa14eec5f15d97c84c36896871335f6ddfb |
| Issue introduced in 6.2 with commit c4bcfb38a95edb1021a53f2d0356a78120ecfbe4 and fixed in 6.12.17 with commit fac674d2bd68f3479f27328626b42d1eebd11fef |
| Issue introduced in 6.2 with commit c4bcfb38a95edb1021a53f2d0356a78120ecfbe4 and fixed in 6.13.5 with commit fcec95b4ab3e7bc6b2f36e5d59f7e24104ea87f7 |
| Issue introduced in 6.2 with commit c4bcfb38a95edb1021a53f2d0356a78120ecfbe4 and fixed in 6.14 with commit c78f4afbd962f43a3989f45f3ca04300252b19b5 |
| |
| 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-2024-58088 |
| 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: |
| kernel/bpf/bpf_cgrp_storage.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/6ecb9fa14eec5f15d97c84c36896871335f6ddfb |
| https://git.kernel.org/stable/c/fac674d2bd68f3479f27328626b42d1eebd11fef |
| https://git.kernel.org/stable/c/fcec95b4ab3e7bc6b2f36e5d59f7e24104ea87f7 |
| https://git.kernel.org/stable/c/c78f4afbd962f43a3989f45f3ca04300252b19b5 |
