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 CFBC5332634; Fri, 15 May 2026 16:33:01 +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=1778862781; cv=none; b=BjsIMA3ZS6R9bVyzNwZqgttO4l3b+6VnkdG6A/7yV8VRu2T/jBuX9tgRWTeDLHi3KtGz4HlsjhRqwDAamSSgz1GySi/GvJLQfyySmbv0AUs1mM2+k8slr2mjqmx9M4NzR6foJynCsjJZp53gSxLsP4TUbIap8PkiMdTmOf2k2i0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778862781; c=relaxed/simple; bh=qnrNxDPeQTij3KCEz75d0pJ5Md2k75uSFkxT9r2Zg8c=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=jt8ZYduWtooeKfgDPfx0xla/fc8VKSQpgLhy5jFUSboCViAia4Q3K9E5sKnSaDqnoX8dzpwOrhUSGF3ICrJPzOQ6s41Yzn4064CvwvdVSBhTV8ietwGFRTH/68Og6MM7tAEKtkcTcwPKHl0lUaYe3WcTILKTx+0JxZ6oie9DJYU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=P+ffmQ/j; 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="P+ffmQ/j" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 367B5C2BCB0; Fri, 15 May 2026 16:33:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1778862781; bh=qnrNxDPeQTij3KCEz75d0pJ5Md2k75uSFkxT9r2Zg8c=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=P+ffmQ/jn9I5Jp9/RVh2Kv5VvQ3RfcE7CqR1dSHg4DXA5BBeJuaBb1hy+E1UG3ODN eztMsv23qmvdtXqMrABzOy5wvdAQW8Hi/XyN8q+3lOG9RABLFArH02HfLG1/ixlkB/ I73VJ+62Y8JabvE5Jl+d+pLlVZw9fesqZxCnyBLo= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Ashutosh Desai , =?UTF-8?q?Ma=C3=ADra=20Canal?= Subject: [PATCH 7.0 128/201] drm/v3d: Reject empty multisync extension to prevent infinite loop Date: Fri, 15 May 2026 17:49:06 +0200 Message-ID: <20260515154701.338257913@linuxfoundation.org> X-Mailer: git-send-email 2.54.0 In-Reply-To: <20260515154658.538039039@linuxfoundation.org> References: <20260515154658.538039039@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 7.0-stable review patch. If anyone has any objections, please let me know. ------------------ From: Ashutosh Desai commit fb44d589bf3148e13452185a6e772a7efbf2d684 upstream. 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 Signed-off-by: Greg Kroah-Hartman --- drivers/gpu/drm/v3d/v3d_submit.c | 5 +++++ 1 file changed, 5 insertions(+) --- 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 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)