| 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-2024-40925: block: fix request.queuelist usage in flush |
| |
| Description |
| =========== |
| |
| In the Linux kernel, the following vulnerability has been resolved: |
| |
| block: fix request.queuelist usage in flush |
| |
| Friedrich Weber reported a kernel crash problem and bisected to commit |
| 81ada09cc25e ("blk-flush: reuse rq queuelist in flush state machine"). |
| |
| The root cause is that we use "list_move_tail(&rq->queuelist, pending)" |
| in the PREFLUSH/POSTFLUSH sequences. But rq->queuelist.next == xxx since |
| it's popped out from plug->cached_rq in __blk_mq_alloc_requests_batch(). |
| We don't initialize its queuelist just for this first request, although |
| the queuelist of all later popped requests will be initialized. |
| |
| Fix it by changing to use "list_add_tail(&rq->queuelist, pending)" so |
| rq->queuelist doesn't need to be initialized. It should be ok since rq |
| can't be on any list when PREFLUSH or POSTFLUSH, has no move actually. |
| |
| Please note the commit 81ada09cc25e ("blk-flush: reuse rq queuelist in |
| flush state machine") also has another requirement that no drivers would |
| touch rq->queuelist after blk_mq_end_request() since we will reuse it to |
| add rq to the post-flush pending list in POSTFLUSH. If this is not true, |
| we will have to revert that commit IMHO. |
| |
| This updated version adds "list_del_init(&rq->queuelist)" in flush rq |
| callback since the dm layer may submit request of a weird invalid format |
| (REQ_FSEQ_PREFLUSH | REQ_FSEQ_POSTFLUSH), which causes double list_add |
| if without this "list_del_init(&rq->queuelist)". The weird invalid format |
| problem should be fixed in dm layer. |
| |
| The Linux kernel CVE team has assigned CVE-2024-40925 to this issue. |
| |
| |
| Affected and fixed versions |
| =========================== |
| |
| Issue introduced in 6.6 with commit 81ada09cc25e4bf2de7d2951925fb409338a545d and fixed in 6.6.35 with commit fe1e395563ccb051e9dbd8fa99859f5caaad2e71 |
| Issue introduced in 6.6 with commit 81ada09cc25e4bf2de7d2951925fb409338a545d and fixed in 6.9.6 with commit 87907bd69721a8506618a954d41a1de3040e88aa |
| Issue introduced in 6.6 with commit 81ada09cc25e4bf2de7d2951925fb409338a545d and fixed in 6.10 with commit d0321c812d89c5910d8da8e4b10c891c6b96ff70 |
| |
| 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-2024-40925 |
| 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-flush.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/fe1e395563ccb051e9dbd8fa99859f5caaad2e71 |
| https://git.kernel.org/stable/c/87907bd69721a8506618a954d41a1de3040e88aa |
| https://git.kernel.org/stable/c/d0321c812d89c5910d8da8e4b10c891c6b96ff70 |
