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 4DA2F1C84A6 for ; Wed, 24 Jun 2026 16:26:16 +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=1782318377; cv=none; b=XtSAr2/5+nCUEhkgs1KxOhXmd2hVeN5IPEup3Y4+FU3f3q1l0u5VzS2n7B+//J+CMXXoAlUxvzrMxJ6/kqh1sOCcPomOa5b9QUFoeCgcfxmlwTDcpJx67T8iCNjPiMvBRWFFcZjLh5prGT96vexxHZYLSE0Fp9KHI7eyF5OdFSs= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782318377; c=relaxed/simple; bh=Qqw0RdC/A29PKBWwpwi3wpO6QLXDVx9q3CxGBLtXmlk=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=sxbpgHzMkY12H7dJUPCI1cu4XcGlWthzFgMYp9uFoA3RU+sNHNVbOIs0EUE7fOpsOsDEC9GL8Mf1mBIMNwtJSEvPd2E41uEcJPV0tYx1/s1rUYGJ3RSwWx5CVBGaCzogsaEpOK/xg5DJZuy+xDOLVLaQ6bqON+adgJI/JB/bhKc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=FIEWgIZl; 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="FIEWgIZl" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 44C5C1F000E9; Wed, 24 Jun 2026 16:26:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1782318375; bh=oghUybY949nNp0CfCirxcG0hyn32I+I+4M57JAwJZb4=; h=From:To:Cc:Subject:Date:Reply-To; b=FIEWgIZlaTLRApu9KuXa+NDimyu999OKpxYTucMTKJmCqNIsnzRaitdaWTLc+1DXR /oaAzz42Fyl0gKGHBvhYeO42+j1D4VMobG86liKpZSnYr5ONsTTn957dXJQpWVxgGW eSXvg5X6Z2vVzM9plG+3HhnV4YW1hbfbAr02KeP8= From: Greg Kroah-Hartman To: linux-cve-announce@vger.kernel.org Cc: Greg Kroah-Hartman Subject: CVE-2026-52946: fs/fcntl: fix SOFTIRQ-unsafe lock order in fasync signaling Date: Wed, 24 Jun 2026 17:25:02 +0100 Message-ID: <2026062402-CVE-2026-52946-bf2a@gregkh> X-Mailer: git-send-email 2.54.0 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=4434; i=gregkh@linuxfoundation.org; h=from:subject:message-id; bh=5AWTanhrU4KjPbd4MNB8X5aNT6PRenpvm+6VfZ6ItJc=; b=owGbwMvMwCRo6H6F97bub03G02pJDFk2LPesXs75ZJ/wYtcO2YMWz42K2Zq4NjcuXa4oVXlfk r+Q+eDVjlgWBkEmBlkxRZYv23iO7q84pOhlaHsaZg4rE8gQBi5OAZjItz6GeYqh708yb+vn0HbK irYTMCyRNPrswLBg5pW9+wMWbJ8YMF3289Ita75ZV5zNAgA= 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: fs/fcntl: fix SOFTIRQ-unsafe lock order in fasync signaling A SOFTIRQ-safe to SOFTIRQ-unsafe lock order deadlock can occur in send_sigio() and send_sigurg() when a process group receives a signal. When FASYNC is configured for a process group (PIDTYPE_PGID), both functions use read_lock(&tasklist_lock) to traverse the task list. However, they are frequently called from softirq context: - send_sigio() via input_inject_event -> kill_fasync - send_sigurg() via tcp_check_urg -> sk_send_sigurg (NET_RX_SOFTIRQ) The deadlock is caused by the rwlock writer fairness mechanism: 1. CPU 0 (process context) holds read_lock(&tasklist_lock) in do_wait(). 2. CPU 1 (process context) attempts write_lock(&tasklist_lock) in fork() or exit() and spins, which blocks all new readers. 3. CPU 0 is interrupted by a softirq (e.g., TCP URG packet reception). 4. The softirq calls send_sigurg() and attempts to acquire read_lock(&tasklist_lock), deadlocking because CPU 1 is waiting. Since PID hashing and do_each_pid_task() traversals are already RCU-protected, the read_lock on tasklist_lock is no longer strictly required for safe traversal. Fix this by replacing tasklist_lock with rcu_read_lock(), aligning the process group signaling path with the single-PID path. This also mitigates a potential remote denial of service vector via TCP URG packets. Lockdep splat: ===================================================== WARNING: SOFTIRQ-safe -> SOFTIRQ-unsafe lock order detected [...] Chain exists of: &dev->event_lock --> &f_owner->lock --> tasklist_lock Possible interrupt unsafe locking scenario: CPU0 CPU1 ---- ---- lock(tasklist_lock); local_irq_disable(); lock(&dev->event_lock); lock(&f_owner->lock); lock(&dev->event_lock); *** DEADLOCK *** The Linux kernel CVE team has assigned CVE-2026-52946 to this issue. Affected and fixed versions =========================== Fixed in 5.10.259 with commit 54626335ea4174ab2d9a183b511d825f6765e47b Fixed in 5.15.210 with commit 897d6a7247739fb1528f98c575df4f2e5de7f994 Fixed in 6.1.176 with commit 32dbd5ce4be3a3ed7e00f8af18795cc84fc50a33 Fixed in 6.6.143 with commit b5fa9e32fb6718f70c986ee14dd5d01b4846f331 Fixed in 6.12.94 with commit 1bee417678f1135e35b25a37734db46aa94258d2 Fixed in 6.18.36 with commit 20a93e397abe850c49b6fa0e8cc827b5f634a8f5 Fixed in 7.0.13 with commit bfcc8e8d8a495bb34cae9e620adfb75fb13a3954 Fixed in 7.1.1 with commit 36c1b57b2ecf3c61ac93f5f07bd29b6f21e226ed 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-2026-52946 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/fcntl.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/54626335ea4174ab2d9a183b511d825f6765e47b https://git.kernel.org/stable/c/897d6a7247739fb1528f98c575df4f2e5de7f994 https://git.kernel.org/stable/c/32dbd5ce4be3a3ed7e00f8af18795cc84fc50a33 https://git.kernel.org/stable/c/b5fa9e32fb6718f70c986ee14dd5d01b4846f331 https://git.kernel.org/stable/c/1bee417678f1135e35b25a37734db46aa94258d2 https://git.kernel.org/stable/c/20a93e397abe850c49b6fa0e8cc827b5f634a8f5 https://git.kernel.org/stable/c/bfcc8e8d8a495bb34cae9e620adfb75fb13a3954 https://git.kernel.org/stable/c/36c1b57b2ecf3c61ac93f5f07bd29b6f21e226ed https://git.kernel.org/stable/c/00633c4683828acd5256fa8d5163f440d74bbe71