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 7BB80585981 for ; Fri, 11 Sep 2026 20:06:34 +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=1789157197; cv=none; b=QYcMTWdGNzISEChyVcfodQWIS5+kcgK3OM+d9C7sj5PXW5aLpb9JYmZY5s0k7sPH0bU9wcEXYpD++g0otJepBXgF21AKdesUM66Q4+fCi5frtgZl38J3sTFtjnrvVNPNOOmOZBNQYftbOsBMb015aBK6T0DSwrGaLE1Ymwf4PKE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789157197; c=relaxed/simple; bh=usPE9cwM6IlLuriq5zGYfGkPdHj4hpvJHPlvfVIjeso=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=EutMzlLPByAo7f2AHwvMFqqQ0uha38RZdRJ9fPF0qOjCvyrFYY7gMhqAnku3nUEniwjA8aeSplzavrxm/LTLZtsCOIzg/kOxP5jskTQmjdVX+NTUpUdO3xJa4/YGvG8IM+X3VeoOhqxMhPlfomUjCU7uSsv/fvkWEveXv3KxQKw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=OoJJF8BP; 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="OoJJF8BP" Received: by smtp.kernel.org (Postfix) with ESMTPSA id D78411F000FF; Fri, 11 Sep 2026 20:06:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1789157193; bh=GnfBRxnEMyAHuqwwvZVM7/XbLz/SZzGzKY/MyWj7EOE=; h=From:To:Cc:Subject:Date:Reply-To; b=OoJJF8BPX9C7IDQP9riNfbgdz6E0HFBWKkVmO0lIpVe6/P8Cu6NN564n1p4cR3qil dM3TLth6R4fSdiHJP63fnHi+qr6Rzh6ZLbf5115W4YXyCXBIfNVspdGpV9x6PrXf4c ekVroJhmd8wto7vWjEIEaB9tJXrMH+XFVcZ/b4AY= From: Greg Kroah-Hartman To: linux-cve-announce@vger.kernel.org Cc: Greg Kroah-Hartman Subject: CVE-2026-89766: pidfd: hold exec_update_lock around namespace ioctl Date: Fri, 11 Sep 2026 21:47:35 +0200 Message-ID: <2026091110-CVE-2026-89766-8b77@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=3203; i=gregkh@linuxfoundation.org; h=from:subject:message-id; bh=UE8mqZXlxGI5IC4WqA9dtngaiEpHrSW8OKL9GY7b6W0=; b=owGbwMvMwCRo6H6F97bub03G02pJDFlLIidN5Tne2+yWujs+Z0r8frNOg5vafCwJv9knr8hwF vz2LvF8RywLgyATg6yYIsuXbTxH91ccUvQytD0NM4eVCWQIAxenAEzEKphhruBDjj+bQg3/FYi/ kRV+Y/bUVOWUD8OCbfHf51hdnzEt1Ven798BMzmNvxPKAA== 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: pidfd: hold exec_update_lock around namespace ioctl The PIDFD_GET_*_NAMESPACE ioctls in pidfd_ioctl() perform a filesystem credentials ptrace access check before handing out a namespace file descriptor. The accompanying comment states that the code "mirrors nsfs behavior", but, unlike the corresponding procfs paths, it does so without holding the target task's exec_update_lock. proc_ns_get_link() and proc_ns_readlink() both take exec_update_lock for reading around the ptrace check and the namespace lookup, so that the credentials used for the access decision match those of the task when its namespace is read. Without it, a caller can pass the check against the target's old credentials and then read the namespace after the target has execve()'d a setuid binary and committed new credentials -- accessing namespace information it should have been denied. Hold exec_update_lock for reading around the ptrace check and the namespace lookup so that pidfd truly mirrors nsfs behavior, as the comment already claims. open_namespace() itself runs outside the lock: once a namespace reference is obtained it carries its own refcount and is opened with the caller's own credentials, so a concurrent execve() on the target can no longer affect the outcome. The Linux kernel CVE team has assigned CVE-2026-89766 to this issue. Affected and fixed versions =========================== Issue introduced in 6.11 with commit 5b08bd408534bfb3a7cf5778da5b27d4e4fffe12 and fixed in 6.18.51 with commit cf24ce48d60225fdbee68ed2058763a1fd172ff3 Issue introduced in 6.11 with commit 5b08bd408534bfb3a7cf5778da5b27d4e4fffe12 and fixed in 7.2.4 with commit e89318aa8629969e86548b05e7c19283af3f0efb Issue introduced in 6.11 with commit 5b08bd408534bfb3a7cf5778da5b27d4e4fffe12 and fixed in 7.3-rc1 with commit 9688a46802939da28f00cb40e8129615d5d4af39 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-2026-89766 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/pidfs.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/cf24ce48d60225fdbee68ed2058763a1fd172ff3 https://git.kernel.org/stable/c/e89318aa8629969e86548b05e7c19283af3f0efb https://git.kernel.org/stable/c/9688a46802939da28f00cb40e8129615d5d4af39