ghsa-v63c-pgjm-vxv9
Vulnerability from github
In the Linux kernel, the following vulnerability has been resolved:
md: Don't ignore read-only array in md_check_recovery()
Usually if the array is not read-write, md_check_recovery() won't register new sync_thread in the first place. And if the array is read-write and sync_thread is registered, md_set_readonly() will unregister sync_thread before setting the array read-only. md/raid follow this behavior hence there is no problem.
After commit f52f5c71f3d4 ("md: fix stopping sync thread"), following hang can be triggered by test shell/integrity-caching.sh:
1) array is read-only. dm-raid update super block: rs_update_sbs ro = mddev->ro mddev->ro = 0 -> set array read-write md_update_sb
2) register new sync thread concurrently.
3) dm-raid set array back to read-only: rs_update_sbs mddev->ro = ro
4) stop the array: raid_dtr md_stop stop_sync_thread set_bit(MD_RECOVERY_INTR, &mddev->recovery); md_wakeup_thread_directly(mddev->sync_thread); wait_event(..., !test_bit(MD_RECOVERY_RUNNING, &mddev->recovery))
5) sync thread done: md_do_sync set_bit(MD_RECOVERY_DONE, &mddev->recovery); md_wakeup_thread(mddev->thread);
6) daemon thread can't unregister sync thread: md_check_recovery if (!md_is_rdwr(mddev) && !test_bit(MD_RECOVERY_NEEDED, &mddev->recovery)) return; -> -> MD_RECOVERY_RUNNING can't be cleared, hence step 4 hang;
The root cause is that dm-raid manipulate 'mddev->ro' by itself, however, dm-raid really should stop sync thread before setting the array read-only. Unfortunately, I need to read more code before I can refacter the handler of 'mddev->ro' in dm-raid, hence let's fix the problem the easy way for now to prevent dm-raid regression.
{
"affected": [],
"aliases": [
"CVE-2024-26757"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2024-04-03T17:15:52Z",
"severity": null
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\nmd: Don\u0027t ignore read-only array in md_check_recovery()\n\nUsually if the array is not read-write, md_check_recovery() won\u0027t\nregister new sync_thread in the first place. And if the array is\nread-write and sync_thread is registered, md_set_readonly() will\nunregister sync_thread before setting the array read-only. md/raid\nfollow this behavior hence there is no problem.\n\nAfter commit f52f5c71f3d4 (\"md: fix stopping sync thread\"), following\nhang can be triggered by test shell/integrity-caching.sh:\n\n1) array is read-only. dm-raid update super block:\nrs_update_sbs\n ro = mddev-\u003ero\n mddev-\u003ero = 0\n -\u003e set array read-write\n md_update_sb\n\n2) register new sync thread concurrently.\n\n3) dm-raid set array back to read-only:\nrs_update_sbs\n mddev-\u003ero = ro\n\n4) stop the array:\nraid_dtr\n md_stop\n stop_sync_thread\n set_bit(MD_RECOVERY_INTR, \u0026mddev-\u003erecovery);\n md_wakeup_thread_directly(mddev-\u003esync_thread);\n wait_event(..., !test_bit(MD_RECOVERY_RUNNING, \u0026mddev-\u003erecovery))\n\n5) sync thread done:\n md_do_sync\n set_bit(MD_RECOVERY_DONE, \u0026mddev-\u003erecovery);\n md_wakeup_thread(mddev-\u003ethread);\n\n6) daemon thread can\u0027t unregister sync thread:\n md_check_recovery\n if (!md_is_rdwr(mddev) \u0026\u0026\n !test_bit(MD_RECOVERY_NEEDED, \u0026mddev-\u003erecovery))\n return;\n -\u003e -\u003e MD_RECOVERY_RUNNING can\u0027t be cleared, hence step 4 hang;\n\nThe root cause is that dm-raid manipulate \u0027mddev-\u003ero\u0027 by itself,\nhowever, dm-raid really should stop sync thread before setting the\narray read-only. Unfortunately, I need to read more code before I\ncan refacter the handler of \u0027mddev-\u003ero\u0027 in dm-raid, hence let\u0027s fix\nthe problem the easy way for now to prevent dm-raid regression.",
"id": "GHSA-v63c-pgjm-vxv9",
"modified": "2024-04-03T18:30:42Z",
"published": "2024-04-03T18:30:42Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2024-26757"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/2ea169c5a0b1134d573d07fc27a16f327ad0e7d3"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/55a48ad2db64737f7ffc0407634218cc6e4c513b"
}
],
"schema_version": "1.4.0",
"severity": []
}