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 0E3CA5867EC for ; Fri, 11 Sep 2026 19:59:37 +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=1789156785; cv=none; b=u5Ak0ZIMQf/69F9uoRnjuHCqaU514AqL/mGSaCRTRpWYa7x24MLELj7UeC7VEP3cbe+GSSuVurgcs/4Y0gYmGh0dAx314RN7DJPBBmKFsqGCXukLfjpZEnzMNCkgMrupr88wMwrCXGYj/I+kCNzfoLoQ/B4SK8fWaYxSsfxMmPQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789156785; c=relaxed/simple; bh=HrrW+ZN3LU2Ud4+yVmzUaC8JBSKEnByefe5VDjmuYiM=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=KJ5a4mhHZJwpwjYDI3WdessH36rxkCA/TcLJ44EzJfr8/l/qgwlk8fEkwWXIeQbNzi0aXPmRwPeOAtrUIeYb+1mM5JN0JhpgiHJmVUqC3DzfWyD7mgY1usUup6w1Ja1xwpDXLKPTWQvKNcRIGPRRy/6Wf7AU8m7HSmIG26dqTpw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=T3ZjApVj; 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="T3ZjApVj" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 31E301F00898; Fri, 11 Sep 2026 19:59:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1789156774; bh=AE2YxHW7FqUq0vB2L6iuoB0+18Sq8pC6iVn37b67fdg=; h=From:To:Cc:Subject:Date:Reply-To; b=T3ZjApVjLGwPKwAy/ZOIfXYErpq5dbW8hEPMgTTXt9CmVHg0vjC/M4MgaN8VB6MMW LeGHPEt+c+kYJpkRFeqCvCv3RMGDujyzTMND4e3OqquutxJozOUCFZ2bxMgn64WcEV o9aUXAv4546dBuREaI5FloQi4Z/FOGAh42G6heNo= From: Greg Kroah-Hartman To: linux-cve-announce@vger.kernel.org Cc: Greg Kroah-Hartman Subject: CVE-2026-89595: fsnotify: Fix stale object mask after concurrent mark updates Date: Fri, 11 Sep 2026 21:44:44 +0200 Message-ID: <2026091131-CVE-2026-89595-944c@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=3747; i=gregkh@linuxfoundation.org; h=from:subject:message-id; bh=z4B+eLuH3tddUrNpLfHafD4N0HQNQs0/V2HWd17xq8U=; b=owGbwMvMwCRo6H6F97bub03G02pJDFlLIrNNHsRu4ZtZ/TNlos15s+efnc7aMej8UtWz+C107 fAc9UzRjhgWBkEmBlkxRZYv23iO7q84pOhlaHsaZg4rE8gQBi5OAZiI+xKGBSuKvpwUSn3pUy5R diIzym5j3E/9XwwzJvLcL85RZbneOm9G8T6Hg5ofTykBAA== 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: fsnotify: Fix stale object mask after concurrent mark updates When a mark gets a new event bit, fanotify and inotify may avoid recalculating the object mask if the cached aggregate already contains that bit. This is racy with a recalculation triggered by a concurrent update to another mark on the same connector. The concurrent scan can read the mark before the new bit is added, while the updater reads the old aggregate before that scan publishes its result. The updater then skips recalculation and the scan publishes a mask without the bit, leaving the object mask stale after both updates complete. This can be reproduced with two fanotify groups watching the same inode: one thread removes FAN_MODIFY from one existing mark while another thread adds FAN_MODIFY to the other mark. After both fanotify_mark() calls return, writes can fail to produce FAN_MODIFY for the group whose mark now contains the bit. This was reproduced on an unmodified v6.12.95 kernel. The equivalent inotify interleaving loses IN_MODIFY events. For normal fanotify additions, recalculate whenever the raw mark mask changes. The normal mask is not cleared asynchronously, so an unchanged addition cannot introduce missing interest. Always recalculate ignore-mask updates because FS_MODIFY handling may clear the ignore mask without taking mark->lock, making snapshot comparisons unreliable. Always recalculate after updating an existing inotify watch. Its replace path temporarily sets mark->mask to zero, so a concurrent scan can observe zero even when the old and final masks are equal. Assigning the replacement mask directly would avoid the transient zero, but existing-watch updates are infrequent, so unconditional recalculation is simpler. The Linux kernel CVE team has assigned CVE-2026-89595 to this issue. Affected and fixed versions =========================== Issue introduced in 2.6.31 with commit 63c882a05416e18de6fb59f7dd6da48f3bbe8273 and fixed in 6.18.51 with commit 947400af98b9e63841929d079a2c3ea0a8ba227b Issue introduced in 2.6.31 with commit 63c882a05416e18de6fb59f7dd6da48f3bbe8273 and fixed in 7.2.4 with commit ac8d8b599d466a129122bded77db3d0f8b96b461 Issue introduced in 2.6.31 with commit 63c882a05416e18de6fb59f7dd6da48f3bbe8273 and fixed in 7.3-rc1 with commit e422777fdd4746de1109575c51e65038d4c5c1be 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-2026-89595 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/notify/fanotify/fanotify_user.c fs/notify/inotify/inotify_user.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/947400af98b9e63841929d079a2c3ea0a8ba227b https://git.kernel.org/stable/c/ac8d8b599d466a129122bded77db3d0f8b96b461 https://git.kernel.org/stable/c/e422777fdd4746de1109575c51e65038d4c5c1be