From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 22B3F4E4C5B for ; Thu, 17 Sep 2026 16:18:47 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789661929; cv=none; b=VngMIL1H4X2MnLahEx5KVT+mYX1jdTeUwXGeH3OSNfV9hbMNp+9PF0HSTjbWzvLiYs0aeucJMBkwqGRelCTHGgRLzGgnR2x9WO3e5vwUhT9Kw3ST+gJXItyppGLe1LUsy02kPr9/saCmaL74amre+wJjHa7ZvpLGg4cC6dOFuXc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789661929; c=relaxed/simple; bh=2XPaCkd8S8/4nkHl0qxCvOIJpDu6SOQUoPGa+AUz1tE=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=AN7yykQOYWcf/gPVddY4uTy/2fhlLlyGMPd+57JhSF5SndMhmV6NtzXdj6woTxZwvtAuJtTO0z+oxh9tun4jXXAyoAC9r04GpbyZe+r9eNlJXyBxIOjfvr4elccf6rj3q4lW/LHvq8vX8yYOOzw32HSx2jWNhyuPQ7AfAdEeAm0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=Oo2BM0R6; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="Oo2BM0R6" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 7946D1F000FF; Thu, 17 Sep 2026 16:18:46 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1789661927; bh=YAi8wwfzzRf9tevWGV8CenrVo91fxS2GL0Fw5iLVSuo=; h=From:To:Cc:Subject:Date:Reply-To; b=Oo2BM0R6atYVJJbYfQJYTCbtSOikSwBeoL0H46/3H9eshiNhEuQ8rX6i22AZqv8t9 PQBIjiivnvjyKwoVqPPqJW1ptz21VoHb5srTh8hH5g1yG/z1C+ewEdUddsCEAu0CHR Xtt5TXdCVeunxmnhQGx9S39EcH8i1OPgsJM6zd4o= From: Greg Kroah-Hartman To: linux-cve-announce@vger.kernel.org Cc: Greg Kroah-Hartman Subject: CVE-2026-90183: blk-iolatency: clear delay state when freeing policy data Date: Thu, 17 Sep 2026 17:10:13 +0100 Message-ID: <2026091730-CVE-2026-90183-a8ca@gregkh> X-Mailer: git-send-email 2.55.0 Reply-To: , Precedence: bulk X-Mailing-List: linux-cve-announce@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=2988; i=gregkh@linuxfoundation.org; h=from:subject:message-id; bh=IO/lgISOQchC+3CddzkM/2znweevXSXFOX7RjTLlVeU=; b=owGbwMvMwCRo6H6F97bub03G02pJDFlrBOraP93TuX/yXugCS4M+nYfM5lLljALOFkURiTV8W 4uvtMV1xLIwCDIxyIopsnzZxnN0f8UhRS9D29Mwc1iZQIYwcHEKwEQeVTEsOMVRGVkxZ2LW096s v47G7B/uaWmbMSzo7kw9lZ6vt5BRuFe7U+dfR3jk3TUA X-Developer-Key: i=gregkh@linuxfoundation.org; a=openpgp; fpr=F4B60CC5BF78C2214A313DCB3147D40DDB2DFB29 Content-Transfer-Encoding: 8bit From: Greg Kroah-Hartman Description =========== In the Linux kernel, the following vulnerability has been resolved: blk-iolatency: clear delay state when freeing policy data io.latency can throttle a group which has no latency target of its own. When a sibling misses its target, check_scale_change() scales down its peers, and a peer that reaches queue depth one gets blkcg_use_delay() called on it on every further scale-down, even with min_lat_nsec == 0. iolatency_pd_offline() resets the target through iolatency_set_min_lat_nsec(), which clears the delay only on a nonzero to zero transition, so it never clears such a peer. Freeing the policy data then leaves blkg->use_delay set and blkcg->congestion_count elevated with nothing left that can drop it. blk_cgroup_congested() then returns true for every task in that cgroup and its descendants for as long as the cgroup lives: page_cache_sync_ra() cuts readahead to a single page, page_cache_async_ra() skips it altogether, and __folio_throttle_swaprate() takes swap_avail_lock and schedules a throttle on anonymous folio allocation. Clear the delay in iolatency_pd_free(). By then bio-held blkg references have drained, or the queue is frozen for policy deactivation, so check_scale_change() cannot re-arm it. The free callback can also see policy data which was never attached to a blkg, hence the pd->blkg check. The Linux kernel CVE team has assigned CVE-2026-90183 to this issue. Affected and fixed versions =========================== Issue introduced in 4.19 with commit d70675121546c35feaceebf7ed9caed8716640f3 and fixed in 7.2.6 with commit 02f1b90ab33ef99c89dd96a385b432ff57abc64d Issue introduced in 4.19 with commit d70675121546c35feaceebf7ed9caed8716640f3 and fixed in 7.3-rc1 with commit 8935bf22c0a0db517a7f72f7097300e05dd852f5 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-2026-90183 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-iolatency.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/02f1b90ab33ef99c89dd96a385b432ff57abc64d https://git.kernel.org/stable/c/8935bf22c0a0db517a7f72f7097300e05dd852f5