From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pf1-f178.google.com (mail-pf1-f178.google.com [209.85.210.178]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 76E2F3AFCE5 for ; Thu, 30 Jul 2026 06:27:26 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.210.178 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785392850; cv=none; b=H9FZlmxp40mvs/CJ4p5VdCM0CSDt0R0QkMdnTLBGVp1hbBRut2OdMuCpO1T2HuBv0snsqRCu9JIMVGhhPgonSWI0qS+2OV6ESFk5C3U2GMzK0tJCyik+vfH3PRlDfmXgaoqOAiWEGU/dEi1Av99TCblhLbYGShSl25Ag32MPdPs= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785392850; c=relaxed/simple; bh=2Wi3i4Vjg7+AxOlXMBs+6tkx40vpBZwTeE7t+8e81gs=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version:Content-Type; b=hB9/ujc0znJNKTdXao+vE+b9t0wV+JBRW0I5OIpbg7RdFAtY9qVFA3uuV6OW9FWxyOzVZu35xJfLp7hfZ4uvorYO/3XESlpTckS937D8QNzbrGLEdzwfD8+QLuIM22rR5rNHM21f4OGUqbT8QawvG/AHpFqO/Mr0bTvU2KMEFd8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=B+md/OeI; arc=none smtp.client-ip=209.85.210.178 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="B+md/OeI" Received: by mail-pf1-f178.google.com with SMTP id d2e1a72fcca58-848479c9bd5so1518244b3a.3 for ; Wed, 29 Jul 2026 23:27:26 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20251104; t=1785392844; x=1785997644; darn=vger.kernel.org; h=content-transfer-encoding:content-type:mime-version:references :in-reply-to:message-id:date:subject:cc:to:from:from:to:cc:subject :date:message-id:reply-to:content-type; bh=3EaYXPThWNdkG4MwcQhWQJEAKHoDeZpU3BU1Rq69yw8=; b=B+md/OeIDFb8CbdHxYmcVZIAnIqqX/0PxEAPc0sODudMj5hJa4Wni0n0HSIkeB95Bp OoNyPiD5XHVMyvUkildU7tARTKa6Im3S5MiE4Je0AVl+o1NA3M9VabwS3zaIbyJf7eJk EjjDGwdWVWiLheMBQ0xx1OzybZHMbMjosGvY5W2LgssP/jbbyTTXTxJE+SMJ0ev3vB7/ XvA9FWeAV+rEegYiiOuRHdArakbWWqeZ5/ZRx+GQhJ6Q6WbjymGwnKo12VntUBXk69p4 sLr4UN20Z2RN3ab7+7YoDUDInmhkRT7aTDIsVPHWniJRtYBZ5TY67v5YnFn3blz+TP5D xdvA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1785392844; x=1785997644; h=content-transfer-encoding:content-type:mime-version:references :in-reply-to:message-id:date:subject:cc:to:from:x-gm-gg :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to :content-type; bh=3EaYXPThWNdkG4MwcQhWQJEAKHoDeZpU3BU1Rq69yw8=; b=pwMprfk5JCYNu5S5XipAF0kYTkt6UOJqv5zzbW3fDBR89S7FAX+Byfa8Ulb3up/3da zqMSbwsGE/4/tUZpNrTu0Cr8x0G835Hs21lgA31vIp0y50shsCNX5t49OwAcg5lCFY5I x8mkSaSkSy9jqNI+q1/e9GMzX5hU8bp75TznGssoLRKvvL/y5b4cqVUwIVs0/wCKv3iU WWMZZqDJGBqhiemZ5swX8oA/eKmBKN1djH7m25Bc1QC09osYZMpxewfS/oQHTJmTB2lC 7VOJrUzXo9HuZK+4DbhJbdaaORWEZJuLu33g0moferx7liJykslX8fUrLH/50NhZmDSa c41Q== X-Gm-Message-State: AOJu0YwYTSebtbBpx0a/zAMRYkoEZP2/HYe3LyVeD/Ox0kwKGI/vl/rc aOVDzNq0M1UPI7hxp4X0yD1ByEU/NqezAEoKmfW/wFaf682+8cUWZKGm X-Gm-Gg: AR+sD12/aD3ZGugWlumerTwPbpnzVy6cKlmLGBVPNZF8x3zfu+i00PMcnBLbZBNpXdX onHX/lBrYSJ8Z7kiPUFWJF+90y11rB0OOd0YjlDn+9C62hpyu0S/r7y1QG7fDa7quv8BlZv/ei9 rZAxKiaPuS9FSJaC5i+0BqV6e1hkIQj8OC2u0Yb0JsppFKamKx3zQvK+u8/pX6o1u27T+rgJKvf s2k12S3pmIbQm6rMOZdPtxcCzE+qzlorHvMOwwbHf2F1Ui5rtwtESuNxNMwA9ST/uKkxmh5YNuy Kr+Dn1oXkQlPkNTixKa3Bpm4c+shr8gSKPhSbF9EayvKgdbw7rNN9N51GbDzpFyR/MmABMvu/5G nPd5A/Hey6ULOpkaECfJ/l5bQAgRMl/A+99Tjao/bjqCvgA6GtUiTfo19MyutzZAdi0XIlvPful eUT2e9fJ1ah96kI/DGnYCi2R+CLZlAicNYN35QWF0+CZ0OcW+/ZEKE19WEb6fWcCxv X-Received: by 2002:a05:6a00:1150:b0:84a:2fff:cef9 with SMTP id d2e1a72fcca58-84ebc1ed97fmr1520110b3a.13.1785392843988; Wed, 29 Jul 2026 23:27:23 -0700 (PDT) Received: from baineng-pc.. ([117.133.183.252]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-84ea00507b0sm2503229b3a.14.2026.07.29.23.27.18 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 29 Jul 2026 23:27:23 -0700 (PDT) From: Baineng Shou To: Sumit Semwal , =?UTF-8?q?Christian=20K=C3=B6nig?= , "T . J . Mercier" , Benjamin Gaignard , Brian Starkey , John Stultz , Sandeep Patil , "Andrew F . Davis" , Srinivas Kandagatla , David Airlie , Simona Vetter Cc: stable@vger.kernel.org, dri-devel@lists.freedesktop.org, linux-media@vger.kernel.org, linaro-mm-sig@lists.linaro.org, linux-kernel@vger.kernel.org, linux-arm-msm@vger.kernel.org, Baineng Shou Subject: [PATCH v5 2/4] misc: fastrpc: don't publish fd before copy_to_user() succeeds Date: Thu, 30 Jul 2026 14:26:43 +0800 Message-Id: <20260730062645.233148-3-shoubaineng@gmail.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20260730062645.233148-1-shoubaineng@gmail.com> References: <20260730062645.233148-1-shoubaineng@gmail.com> 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 fastrpc_ioctl_alloc_dmabuf() calls dma_buf_fd() which installs the fd into the caller's fd table before copy_to_user() copies the fd number back to userspace. If copy_to_user() fails, the fd is already visible to other threads in the same process but the ioctl returns -EFAULT. The existing comment in the code even acknowledges the problem: "The usercopy failed, but we can't do much about it, as dma_buf_fd() already called fd_install()..." Now that dma_buf_fd_install() is available (introduced to fix the same issue in dma-heap), apply the same pattern here: reserve the fd with get_unused_fd_flags(), attempt copy_to_user(), and only on success call dma_buf_fd_install() to publish it atomically with the tracepoint. On copy_to_user() failure, put_unused_fd() and dma_buf_put() cleanly unwind without any user-visible side effects. Fixes: 6cffd79504ce ("misc: fastrpc: Add support for dmabuf exporter") Cc: stable@vger.kernel.org Acked-by: Christian König Signed-off-by: Baineng Shou --- drivers/misc/fastrpc.c | 16 ++++++---------- 1 file changed, 6 insertions(+), 10 deletions(-) diff --git a/drivers/misc/fastrpc.c b/drivers/misc/fastrpc.c index f3a49384586d..c5143cd25767 100644 --- a/drivers/misc/fastrpc.c +++ b/drivers/misc/fastrpc.c @@ -1709,24 +1709,20 @@ static int fastrpc_dmabuf_alloc(struct fastrpc_user *fl, char __user *argp) return err; } - bp.fd = dma_buf_fd(buf->dmabuf, O_ACCMODE); + bp.fd = get_unused_fd_flags(O_ACCMODE); if (bp.fd < 0) { dma_buf_put(buf->dmabuf); - return -EINVAL; + return bp.fd; } if (copy_to_user(argp, &bp, sizeof(bp))) { - /* - * The usercopy failed, but we can't do much about it, as - * dma_buf_fd() already called fd_install() and made the - * file descriptor accessible for the current process. It - * might already be closed and dmabuf no longer valid when - * we reach this point. Therefore "leak" the fd and rely on - * the process exit path to do any required cleanup. - */ + put_unused_fd(bp.fd); + dma_buf_put(buf->dmabuf); return -EFAULT; } + dma_buf_fd_install(buf->dmabuf, bp.fd); + return 0; } -- 2.34.1