From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from fanzine2.igalia.com (fanzine2.igalia.com [213.97.179.56]) (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 97A493AA1A1 for ; Fri, 15 May 2026 21:06:49 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=213.97.179.56 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778879211; cv=none; b=Zt33dMBpJktzolWnuAqC7Of0BKVnAm25+1twLrwc/aF12NcHiyJ37ix6Nv8Kr49IJU/Zp1Inoqr0yCf3OfSsx7Zt0vvXmCYyftyiOl8Mg5Y7Yo1QjRSqji6GqOLZAoRdGK0X48AnFbPjFzEiVhuJSc7UHYMKgytYIyFhVGTQQyc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778879211; c=relaxed/simple; bh=7R5Ewhn9mNNL419/GQcK+BrOXctaVXyzFMWCV6hpP14=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=iRuXrO2J72RFMqzefTXQGoQzbQKwQaVBIDjd9R0RTYg/uNG7PerbWh1V4X1Owd8iQfbgh9+KyEMVBFpZWuj+24LD6/EgMxXrVR+mFIx88PxLLOD4b4mNT2AhA7IRm2XjpS0w6jvEbKcELLwgfHbFfB5Ay4ToMLxb9Kl1hrFwDNU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=igalia.com; spf=pass smtp.mailfrom=igalia.com; dkim=pass (2048-bit key) header.d=igalia.com header.i=@igalia.com header.b=H1mI27QV; arc=none smtp.client-ip=213.97.179.56 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=igalia.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=igalia.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=igalia.com header.i=@igalia.com header.b="H1mI27QV" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=igalia.com; s=20170329; h=Content-Transfer-Encoding:Content-Type:MIME-Version:References: In-Reply-To:Message-ID:Date:Subject:Cc:To:From:Sender:Reply-To:Content-ID: Content-Description:Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc :Resent-Message-ID:List-Id:List-Help:List-Unsubscribe:List-Subscribe: List-Post:List-Owner:List-Archive; bh=IveG5wjKCkPjlbRtGhoU5quq5yd9YXX9jJd4KDgTRzA=; b=H1mI27QVDTONi9LRBnmEsygPx1 NhzuiwZV+fE9jnKTrLCkiEjEDugmEq2XvrQGDeoOW3N/08xLGKUu6roQ+R5Pa79viTQY8V9Xx9hup lgO7YHVzrc+xj3h/D1cKVvgB07zRFrXQ/kU36VJn8tUY0xND5bnxGmZT+c61btDxc/ip8HjSlT1XY mJty/5ghwkv47IamCvKL4W59UmXByxePZ2ervAe0LxayFamCZdMXOZJrOF2F0zJaM8fobQEuXByW3 YSOSPYuVmgrWU7m5oJV9qRjb/SmnKXeII5RTRIIn8Ub6Onsr4nPzxldfL2OreiSpT7r9Ra3flhD0a IFBIw07Q==; Received: from [189.7.87.67] (helo=prince) by fanzine2.igalia.com with esmtpsa (Cipher TLS1.3:ECDHE_X25519__RSA_PSS_RSAE_SHA256__AES_256_GCM:256) (Exim) id 1wNzk5-000h6F-0G; Fri, 15 May 2026 23:06:47 +0200 From: =?UTF-8?q?Ma=C3=ADra=20Canal?= To: stable@vger.kernel.org Cc: kernel-dev@igalia.com, Ashutosh Desai , =?UTF-8?q?Ma=C3=ADra=20Canal?= Subject: [PATCH 6.18.y] drm/v3d: Reject empty multisync extension to prevent infinite loop Date: Fri, 15 May 2026 18:06:22 -0300 Message-ID: <20260515210621.2475109-2-mcanal@igalia.com> X-Mailer: git-send-email 2.54.0 In-Reply-To: <2026051541-twisty-generic-1b1b@gregkh> References: <2026051541-twisty-generic-1b1b@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 From: Ashutosh Desai 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 (cherry picked from commit fb44d589bf3148e13452185a6e772a7efbf2d684) Signed-off-by: Maíra Canal --- drivers/gpu/drm/v3d/v3d_submit.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/drivers/gpu/drm/v3d/v3d_submit.c b/drivers/gpu/drm/v3d/v3d_submit.c index f3652e90683c..23fa18e5e65c 100644 --- a/drivers/gpu/drm/v3d/v3d_submit.c +++ b/drivers/gpu/drm/v3d/v3d_submit.c @@ -390,6 +390,11 @@ 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_DEBUG("Empty multisync extension\n"); + return -EINVAL; + } + ret = v3d_get_multisync_post_deps(file_priv, se, multisync.out_sync_count, multisync.out_syncs); if (ret) -- 2.54.0