From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1794049948; b=C2Opj8BgaT0zFzCHHAsrJa0eiF51BwaHBvvYevilga6qKz+dZBvDNlkjkBJs+gdYGSrZ 41U7ijf8u6QdZ151L//VYddddVyODlTZZjoDVwR5dGu7EEnte+wrbRMgJk6G8BJYK3i5l djIkrZwpkmh+7BaRzWkylurFXFOohVGJxnTh/p42ciMfck7p2LFs5ZWEFcr+3YeWdEQTR tTCf/kz9y39I8rlVVrD4Xdhn/10r0Av5yQg4ewVMoCxM+cdCPeP6LFRwXt5F4SumBsGZ6 Tu/66VN7Ud+klMW6l63sEfU628yQ6cql6p6i1jV59gwLoJlU+x3tSEjYVEeGGI+uKdA== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794049948; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: MIME-Version:Content-Type:Content-Transfer-Encoding; bh=Gnl3SX7mnwqMR1ZSzkhYRCcPItvu5bu6bwhKHhHiqLk=; b=YyMFN+rMylN1f9jdMOLb/RTa2sjmc9bH+ly6His8tJ7eFst6uu1tH5Lt8r4pBA/15ijS Gv2ZCtXTBO9XTAk4RRUiiPqKWWfiNgK99dmkKdVaDBYc53vyw/nmd/D2NWLJ2uhwt1+xG 3rkSN0a1I4tBzuPsh1+r0dhWMr1krPZUoChmS287mM4N/XquQKtw1TYWSWWWozFovBeef Wv8XkhVRLygmAbhJlUi0B6Oa6rnp62Bu68+jz535bACtTvS16jAB2X+bnUbsCuEWemLD9 fQmGnHB9pPu8QkxtiOn3Lu0VwXObMZWi5Vs8qop7X3F6Ez6H3lUqJjXsc35uCaovNpA== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b="EMQ/rdsi"; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 347B0606A32C for ; Sat, 7 Nov 2026 11:12:28 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=EMQ/rdsi Received: by smtp.kernel.org (Postfix) with ESMTPSA id 8DE511F0089F; Sat, 7 Nov 2026 11:12:27 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1794049948; bh=Gnl3SX7mnwqMR1ZSzkhYRCcPItvu5bu6bwhKHhHiqLk=; h=From:To:Cc:Subject:Date; b=EMQ/rdsiQqRCHzZaK4rO6EP6r8FEqSyz5yMEN0rKMspDrNrwvy4JcdVrrSKEoiWeb oE09CKECs7vI0rxvYnqWN8V39I7RyGGcWcnQP0+AjFE/UC3GQitf9Q8vR7VSfZSxFn 8SKTp9j03x7UD9nZOblL91vMqyVTeEr8qZGsr85SlpK6A+qCHAe8RKgnb7WtbbG4lH ocifUGS+0pv0V6hc68xd+6muy8eRXDIJs1GzOeJ+9yJVLZ5X76I/qx2Rf9I1+GGotr uN2UrtpcM9pKTl5iaPkp2cSEy7KIwckVDpQ34UB3vs1hwW5DRn1B7dK+2Sx9PPKaZf +isaDpVQiia6g== From: Sasha Levin To: dmnk@google.com, bvanassche@acm.org, axboe@kernel.dk Cc: stable@vger.kernel.org Subject: FAILED: patch "[PATCH] loop: check for read-write open mode on LOOP_SET_STATUS in lo_compat_ioctl()" failed to apply to 5.15-stable tree Date: Sat, 7 Nov 2026 06:12:26 -0500 Message-ID: <20261107061226-failed-5.15-87409eedc543@kernel.org> X-Mailer: git-send-email 2.53.0 X-Mailing-List: stable@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit The patch below does not apply to the 5.15-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to . To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.15.y git checkout FETCH_HEAD git cherry-pick -x 87409eedc543d288cdd49c2174f7d61eca7b8db5 # git commit -s git send-email --to '' --in-reply-to '20261107061226-failed-5.15-87409eedc543@kernel.org' --subject-prefix 'PATCH 5.15.y' 'HEAD^..' Thanks, Sasha ------------------ original commit in Linus's tree ------------------ >From 87409eedc543d288cdd49c2174f7d61eca7b8db5 Mon Sep 17 00:00:00 2001 From: Dominik Maier Date: Sun, 25 Oct 2026 21:07:40 +0100 Subject: [PATCH] loop: check for read-write open mode on LOOP_SET_STATUS in lo_compat_ioctl() lo_ioctl() checks for (mode & BLK_OPEN_WRITE) || capable(CAP_SYS_ADMIN) before allowing LOOP_SET_STATUS or LOOP_SET_STATUS64, but not lo_compat_ioctl(), the handler used by 32-bit user space on 64-bit kernels. As a result, on 64-bit kernels with CONFIG_COMPAT=y, a 32-bit unprivileged user-space process holding a read-only (O_RDONLY) file descriptor to an active /dev/loopN device can issue a compat LOOP_SET_STATUS ioctl to modify lo_offset, clear lo_sizelimit to 0 (exposing backing-file data past the configured limit), or alter lo_flags. Enforce the same (mode & BLK_OPEN_WRITE) || capable(CAP_SYS_ADMIN) check on LOOP_SET_STATUS in lo_compat_ioctl(). Cc: stable@vger.kernel.org Assisted-by: ARTIST LLM Signed-off-by: Dominik Maier Reviewed-by: Bart Van Assche bvanassche@acm.org Link: https://patch.msgid.link/20261025200740.2064379-1-dmnk@google.com Signed-off-by: Jens Axboe --- drivers/block/loop.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/drivers/block/loop.c b/drivers/block/loop.c index aabaaacdb4fab..a3325ceab484a 100644 --- a/drivers/block/loop.c +++ b/drivers/block/loop.c @@ -1604,8 +1604,10 @@ static int lo_compat_ioctl(struct block_device *bdev, blk_mode_t mode, switch(cmd) { case LOOP_SET_STATUS: - err = loop_set_status_compat(lo, - (const struct compat_loop_info __user *)arg); + err = -EPERM; + if ((mode & BLK_OPEN_WRITE) || capable(CAP_SYS_ADMIN)) + err = loop_set_status_compat(lo, + (const struct compat_loop_info __user *)arg); break; case LOOP_GET_STATUS: err = loop_get_status_compat(lo, -- 2.53.0