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=1794322799; b=XfRmwn7DEZSiD/pSVDirMf6zxfs8it9CnrqEjVk0yLs1717LOYZKT/+JmwIEx5IXCPi5 spkPDW0WXgtY2Z0Hx7jdThCqdICF4UHgcTpWKdIAdK97TNOZ1X9RUlK9BvPiFzoxx0dVl H4HRzbI2YtFFv5tgfaXHStWFH4Bi8xaYbgpyMFz2vdf0c4EYrW1Y6FA0jn9bXyQR2DayD g9b+g/6a+gJEEsFvyRH1RD+39i9PYIskgrIWSxUmrRouRCIyQ5keREadF41HgIcARmlNC YnRwjO/m9Qoz2epY1wMJLYLLg4X5tyMDKxDPQHsSew1VkCvRkg5qv4FO6LALgfdNsbg== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794322799; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:MIME-Version:Content-Transfer-Encoding; bh=mEfMS9ILT1rPQqgbKFW2JGPLsDmYArucIN6/LOvmWlg=; b=blcr1D80ij0uQvxezkMsX+Ynuc3eliTkCbaUGXK4FTgZkODn3mwnj+gwco8ABnOMdON8 B+rIkaL7TnD9mVsRD/t4Mna3tQsT/1h5Sp/IF6M3QeieTm/WUZccmZnIe4N8TTfbpZId8 jRrk0YHxmVW8cLizLHsDfadvhHp1UrwvY5HY65MwD8WQrgLODQbT8d56bCHujqX9sqrcf 0zWe9qdHIeILIzgT6mcnw3F22nJ9E0l408TODLQ/UPf8HyvwjtLkoK4XP8/WjExqP8VwW BBPHS+pIMf9ba6FMeDMwuvowfDiwT+ll+RwXb1BqnsxyW+C75d8xrUoISLIhpguR/HQ== 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="fhR/bpkr"; 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 2DA0660A3801 for ; Tue, 10 Nov 2026 14:59:58 +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=fhR/bpkr Received: by smtp.kernel.org (Postfix) with ESMTPSA id 1729F1F0089F; Tue, 10 Nov 2026 14:59:58 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1794322798; bh=mEfMS9ILT1rPQqgbKFW2JGPLsDmYArucIN6/LOvmWlg=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=fhR/bpkrzFSSmIMFXPeGi7EGbBWtgegYQ4PRkv1o/m+v+sg6uO1PSq8TPaAJ3cDfQ f1jKSeU1whESMyTSZQa68MH+QhK13KuaInyazSSwCoWVOq2o3riQQiR+qvb1RrLP3v NPWiSz9abJefqFAKR0SgC/FDfVBUVz3bHETQiXUhEgrFJeZHaIaBXWSSdD+KSmQGMQ BZIS3TH+4Lk+lKHRgy6yFEnlH+fa+Qmkf9uNMwIaUPz5KMsglznmnyt6rDZ7fhAPOS RFmDNxu+QzzdCj6vjvTmaJX+1FIt4sJeYEQBfyqCBCG46Y1VAXMZ2SCXuGBN4Yzw2d VcmRYYo+XxbLA== From: Sasha Levin To: stable@vger.kernel.org Cc: Yifei Gao , Ekansh Gupta , Srinivas Kandagatla , Greg Kroah-Hartman , Sasha Levin Subject: [PATCH 6.12.y 2/2] misc: fastrpc: fix double-free in fastrpc_map_attach() error path Date: Tue, 10 Nov 2026 09:59:55 -0500 Message-ID: <20261110145948.2017214-2-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20261110145948.2017214-1-sashal@kernel.org> References: <20261107052053-failed-6.12-09fa66ec1b48@kernel.org> <20261110145948.2017214-1-sashal@kernel.org> 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-Transfer-Encoding: 8bit From: Yifei Gao [ Upstream commit 09fa66ec1b4896ab841da085ca58b6433f28f07f ] map->table is assigned right after dma_buf_map_attachment_unlocked() succeeds. The two failure checks that follow, the len > map->size test and, where subsystem VMIDs are configured, a failed qcom_scm_assign_mem(), jump to map_err with map->table already set. map_err manually calls dma_buf_detach() and dma_buf_put() and then falls through to fastrpc_map_put(). Since that change the error path tail is fastrpc_map_put() -> fastrpc_free_map(), and fastrpc_free_map() already unmaps, detaches and puts the dma-buf whenever map->table is set. The two operations therefore run twice: the second dma_buf_put() drops an extra reference on map->buf, and dma_buf_unmap_attachment_unlocked() dereferences the map->attach already freed by the manual dma_buf_detach(). kref_init() sets the refcount to 1 with no intervening get, so the final fastrpc_map_put() frees the map synchronously and the redundant cleanup is deterministic. The len > map->size branch is reachable by an unprivileged process via FASTRPC_IOCTL_MEM_MAP with an fd whose dma-buf is smaller than the requested length, before any DSP invocation. Route both map->table-is-set failure branches to get_err instead of map_err, so fastrpc_free_map() is the single owner of the unmap/detach/put sequence. map_err is retained for the dma_buf_map_attachment_unlocked() failure, which is reached with map->table still NULL and an attachment that fastrpc_free_map() will not clean up, so its dma_buf_detach()/dma_buf_put() must still run manually. Fixes: 334f1a1cbe03 ("misc: fastrpc: Use fastrpc_map_put in fastrpc_map_create on fail") Cc: stable@vger.kernel.org Assisted-by: Claude:claude-opus-4-8 Signed-off-by: Yifei Gao Reviewed-by: Ekansh Gupta Signed-off-by: Srinivas Kandagatla Link: https://patch.msgid.link/20261002101220.1084101-2-srinivas.kandagatla@oss.qualcomm.com Signed-off-by: Greg Kroah-Hartman Signed-off-by: Sasha Levin --- drivers/misc/fastrpc.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/misc/fastrpc.c b/drivers/misc/fastrpc.c index afafaa68e2bd2..a4577ef5a3946 100644 --- a/drivers/misc/fastrpc.c +++ b/drivers/misc/fastrpc.c @@ -857,7 +857,7 @@ static int fastrpc_map_attach(struct fastrpc_user *fl, int fd, dev_dbg(sess->dev, "Bad size passed len 0x%llx map size 0x%llx\n", len, map->size); err = -EINVAL; - goto map_err; + goto get_err; } map->va = sg_virt(map->table->sgl); map->len = len; @@ -880,7 +880,7 @@ static int fastrpc_map_attach(struct fastrpc_user *fl, int fd, dev_err(sess->dev, "Failed to assign memory with dma_addr %pad size 0x%llx err %d\n", &map->dma_addr, map->len, err); - goto map_err; + goto get_err; } } spin_lock(&fl->lock); -- 2.53.0