| 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-2024-40900: cachefiles: remove requests from xarray during flushing requests |
| |
| Description |
| =========== |
| |
| In the Linux kernel, the following vulnerability has been resolved: |
| |
| cachefiles: remove requests from xarray during flushing requests |
| |
| Even with CACHEFILES_DEAD set, we can still read the requests, so in the |
| following concurrency the request may be used after it has been freed: |
| |
| mount | daemon_thread1 | daemon_thread2 |
| ------------------------------------------------------------ |
| cachefiles_ondemand_init_object |
| cachefiles_ondemand_send_req |
| REQ_A = kzalloc(sizeof(*req) + data_len) |
| wait_for_completion(&REQ_A->done) |
| cachefiles_daemon_read |
| cachefiles_ondemand_daemon_read |
| // close dev fd |
| cachefiles_flush_reqs |
| complete(&REQ_A->done) |
| kfree(REQ_A) |
| xa_lock(&cache->reqs); |
| cachefiles_ondemand_select_req |
| req->msg.opcode != CACHEFILES_OP_READ |
| // req use-after-free !!! |
| xa_unlock(&cache->reqs); |
| xa_destroy(&cache->reqs) |
| |
| Hence remove requests from cache->reqs when flushing them to avoid |
| accessing freed requests. |
| |
| The Linux kernel CVE team has assigned CVE-2024-40900 to this issue. |
| |
| |
| Affected and fixed versions |
| =========================== |
| |
| Issue introduced in 5.19 with commit c8383054506c77b814489c09877b5db83fd4abf2 and fixed in 6.1.95 with commit 9f13aacdd4ee9a7644b2a3c96d67113cd083c9c7 |
| Issue introduced in 5.19 with commit c8383054506c77b814489c09877b5db83fd4abf2 and fixed in 6.6.35 with commit 50d0e55356ba5b84ffb51c42704126124257e598 |
| Issue introduced in 5.19 with commit c8383054506c77b814489c09877b5db83fd4abf2 and fixed in 6.9.6 with commit 37e19cf86a520d65de1de9cb330415c332a40d19 |
| Issue introduced in 5.19 with commit c8383054506c77b814489c09877b5db83fd4abf2 and fixed in 6.10 with commit 0fc75c5940fa634d84e64c93bfc388e1274ed013 |
| |
| 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-2024-40900 |
| 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: |
| fs/cachefiles/daemon.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/9f13aacdd4ee9a7644b2a3c96d67113cd083c9c7 |
| https://git.kernel.org/stable/c/50d0e55356ba5b84ffb51c42704126124257e598 |
| https://git.kernel.org/stable/c/37e19cf86a520d65de1de9cb330415c332a40d19 |
| https://git.kernel.org/stable/c/0fc75c5940fa634d84e64c93bfc388e1274ed013 |
