| 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-2024-56672: blk-cgroup: Fix UAF in blkcg_unpin_online() |
| |
| Description |
| =========== |
| |
| In the Linux kernel, the following vulnerability has been resolved: |
| |
| blk-cgroup: Fix UAF in blkcg_unpin_online() |
| |
| blkcg_unpin_online() walks up the blkcg hierarchy putting the online pin. To |
| walk up, it uses blkcg_parent(blkcg) but it was calling that after |
| blkcg_destroy_blkgs(blkcg) which could free the blkcg, leading to the |
| following UAF: |
| |
| ================================================================== |
| BUG: KASAN: slab-use-after-free in blkcg_unpin_online+0x15a/0x270 |
| Read of size 8 at addr ffff8881057678c0 by task kworker/9:1/117 |
| |
| CPU: 9 UID: 0 PID: 117 Comm: kworker/9:1 Not tainted 6.13.0-rc1-work-00182-gb8f52214c61a-dirty #48 |
| Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS unknown 02/02/2022 |
| Workqueue: cgwb_release cgwb_release_workfn |
| Call Trace: |
| <TASK> |
| dump_stack_lvl+0x27/0x80 |
| print_report+0x151/0x710 |
| kasan_report+0xc0/0x100 |
| blkcg_unpin_online+0x15a/0x270 |
| cgwb_release_workfn+0x194/0x480 |
| process_scheduled_works+0x71b/0xe20 |
| worker_thread+0x82a/0xbd0 |
| kthread+0x242/0x2c0 |
| ret_from_fork+0x33/0x70 |
| ret_from_fork_asm+0x1a/0x30 |
| </TASK> |
| ... |
| Freed by task 1944: |
| kasan_save_track+0x2b/0x70 |
| kasan_save_free_info+0x3c/0x50 |
| __kasan_slab_free+0x33/0x50 |
| kfree+0x10c/0x330 |
| css_free_rwork_fn+0xe6/0xb30 |
| process_scheduled_works+0x71b/0xe20 |
| worker_thread+0x82a/0xbd0 |
| kthread+0x242/0x2c0 |
| ret_from_fork+0x33/0x70 |
| ret_from_fork_asm+0x1a/0x30 |
| |
| Note that the UAF is not easy to trigger as the free path is indirected |
| behind a couple RCU grace periods and a work item execution. I could only |
| trigger it with artifical msleep() injected in blkcg_unpin_online(). |
| |
| Fix it by reading the parent pointer before destroying the blkcg's blkg's. |
| |
| The Linux kernel CVE team has assigned CVE-2024-56672 to this issue. |
| |
| |
| Affected and fixed versions |
| =========================== |
| |
| Issue introduced in 5.7 with commit 4308a434e5e08c78676aa66bc626ef78cbef0883 and fixed in 5.10.234 with commit 83f5a87ee8caa76a917f59912a74d6811f773c67 |
| Issue introduced in 5.7 with commit 4308a434e5e08c78676aa66bc626ef78cbef0883 and fixed in 5.15.177 with commit 8a07350fe070017a887433f4d6909433955be5f1 |
| Issue introduced in 5.7 with commit 4308a434e5e08c78676aa66bc626ef78cbef0883 and fixed in 6.1.121 with commit 64afc6fe24c9896c0153e5a199bcea241ecb0d5c |
| Issue introduced in 5.7 with commit 4308a434e5e08c78676aa66bc626ef78cbef0883 and fixed in 6.6.67 with commit 5baa28569c924d9a90d036c2aaab79f791fedaf8 |
| Issue introduced in 5.7 with commit 4308a434e5e08c78676aa66bc626ef78cbef0883 and fixed in 6.12.6 with commit 29d1e06560f0f6179062ac638b4064deb637d1ad |
| Issue introduced in 5.7 with commit 4308a434e5e08c78676aa66bc626ef78cbef0883 and fixed in 6.13 with commit 86e6ca55b83c575ab0f2e105cf08f98e58d3d7af |
| |
| 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-2024-56672 |
| 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: |
| block/blk-cgroup.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/83f5a87ee8caa76a917f59912a74d6811f773c67 |
| https://git.kernel.org/stable/c/8a07350fe070017a887433f4d6909433955be5f1 |
| https://git.kernel.org/stable/c/64afc6fe24c9896c0153e5a199bcea241ecb0d5c |
| https://git.kernel.org/stable/c/5baa28569c924d9a90d036c2aaab79f791fedaf8 |
| https://git.kernel.org/stable/c/29d1e06560f0f6179062ac638b4064deb637d1ad |
| https://git.kernel.org/stable/c/86e6ca55b83c575ab0f2e105cf08f98e58d3d7af |
