From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 BEA01389E1A for ; Fri, 15 May 2026 08:35:27 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778834127; cv=none; b=Wx9VXID2oOhsZTtkdbYLKwOkRUWFI7Wkna62c8i+x9jVsCZ4dUsPNQ8wdczQGBRmwI2kuXpS8P0sdp387TlCEWQoICZIHJASZHPtEoOAuSPeQVzJcSo77WJv6XuAVygA8dF0HjkxxL2PYvPaVsl62rBXEQKUZw/INHJIfBT8lAk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778834127; c=relaxed/simple; bh=0cWNeKYjm98GyutygDKiDSCXBtWO0aICsr4ka2XTfzI=; h=Subject:To:Cc:From:Date:Message-ID:MIME-Version:Content-Type; b=KDQxJdHPrQKN9d9zZVUnaZ2YpYdCSL98MBd+M4i4jypqvTkP5O+FZW3s3WyVgVaTlI+Ynji6lbFFEX+BQAUDbjCexJydS9WICnekGHRlFj8vLl7+REhrlLXnrX36mT44+meAZipeJn2UKWscN3UYTrY3wgbxb9xVd6AbWhz0rS8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=2Zp5WxJE; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="2Zp5WxJE" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 0ECDBC2BCB0; Fri, 15 May 2026 08:35:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1778834127; bh=0cWNeKYjm98GyutygDKiDSCXBtWO0aICsr4ka2XTfzI=; h=Subject:To:Cc:From:Date:From; b=2Zp5WxJEEdMX/fFe49sgEvsr83xxKotIKvApxlTK+hVV76G/SAEDNIMy3ROKxskX1 ZN2AqzhTkARBcz1pvxB0rzWP439gZphGvF/lbGiKlU1+52NlCt8WAicmv4d3BMYzcq Y3Xu6jhL8k3BU9dz3Oh48//m/EZePDHiqvM/CCn8= Subject: FAILED: patch "[PATCH] drm/v3d: Reject empty multisync extension to prevent infinite" failed to apply to 6.6-stable tree To: ashutoshdesai993@gmail.com,mcanal@igalia.com Cc: From: Date: Fri, 15 May 2026 10:35:31 +0200 Message-ID: <2026051531-plexiglas-mumbling-3aa6@gregkh> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit The patch below does not apply to the 6.6-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-6.6.y git checkout FETCH_HEAD git cherry-pick -x fb44d589bf3148e13452185a6e772a7efbf2d684 # git commit -s git send-email --to '' --in-reply-to '2026051531-plexiglas-mumbling-3aa6@gregkh' --subject-prefix 'PATCH 6.6.y' HEAD^.. Possible dependencies: thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From fb44d589bf3148e13452185a6e772a7efbf2d684 Mon Sep 17 00:00:00 2001 From: Ashutosh Desai Date: Wed, 15 Apr 2026 05:00:00 +0000 Subject: [PATCH] drm/v3d: Reject empty multisync extension to prevent infinite loop MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit v3d_get_extensions() walks a userspace-provided singly-linked list of ioctl extensions without any bound on the chain length. A local user can craft a self-referential extension (ext->next == &ext) with zero in_sync_count and out_sync_count, which bypasses the existing duplicate- extension guard: if (se->in_sync_count || se->out_sync_count) return -EINVAL; The guard never fires because v3d_get_multisync_post_deps() returns immediately when count is zero, leaving both fields at zero on every iteration. The result is an infinite loop in kernel context, blocking the calling thread and pegging a CPU core indefinitely. Fix this by rejecting a multisync extension where both in_sync_count and out_sync_count are zero in v3d_get_multisync_submit_deps(). An empty multisync carries no synchronization information and serves no useful purpose, so returning -EINVAL for such an extension is the correct defense against this attack vector. Fixes: e4165ae8304e ("drm/v3d: add multiple syncobjs support") Cc: stable@vger.kernel.org Signed-off-by: Ashutosh Desai Link: https://patch.msgid.link/20260415050000.3816128-1-ashutoshdesai993@gmail.com Signed-off-by: Maíra Canal diff --git a/drivers/gpu/drm/v3d/v3d_submit.c b/drivers/gpu/drm/v3d/v3d_submit.c index 18f2bf1fe89f..fc74351efad5 100644 --- a/drivers/gpu/drm/v3d/v3d_submit.c +++ b/drivers/gpu/drm/v3d/v3d_submit.c @@ -393,6 +393,11 @@ v3d_get_multisync_submit_deps(struct drm_file *file_priv, if (multisync.pad) return -EINVAL; + if (!multisync.in_sync_count && !multisync.out_sync_count) { + drm_dbg(&v3d->drm, "Empty multisync extension\n"); + return -EINVAL; + } + ret = v3d_get_multisync_post_deps(file_priv, se, multisync.out_sync_count, multisync.out_syncs); if (ret)