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=1794590594; b=larIbIpAlYxa0a8h3NIwHKvODAoFXhZ9MiRtBMQNd/JbueETpf/zr1DeVSKRuZEgpTwz lcWZLkGbI2jKCoK2ox23WWWK2p9glsCV5nONSRVGvIJIO11g0TU+agl5nk2paW7JE9ro0 2qJgSvFYSlxxJ4LxReQtMhXQ46LO0D8gfxqLYjbfbU8bxblr/1BQerhxEMlkTKAvoK4gs SLz2SW2r6YMFmY33WvoT8B2vvT8eIsSoytDPpuUxo2MrIPK+H6eFPQ4d6PTSRSkao5AMj qf+iPjpcjNQfFSdssv42+BeIKSbZ5ilwj2M9SoYHjkE+THyy5AbvlIbTQZ4QvuvHRtQ== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794590594; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:User-Agent:X-stable:X-Patchwork-Hint: MIME-Version:Content-Transfer-Encoding; bh=yu+/7QT8+MaZWXZZVIB8P8CvxlJRJb/O9cVb+LQf0H8=; b=vcCQDuqmcb0vSyFFwNbiQe8EiIxV7Mdb6Jm5G++TkfkZ//+ZOxPufYX9KTvgIzkk2jya 5bxWT+iX380v8PJklkLR4jvoaL8n9MT7i40Ogm4Y/taSZcmfIiiu7rKc9EEoxAmOtayut r/SNKiLaJn7FhJIzP/RoUzPJL/xqoyBFGlcpfvtZUB1m8XzbBOsA+ihPTIqDx0G+fO0we WGZLv+wZgcgNRnUdaqL8s4VsPnuYkL8aUTcYQ0K3V3hP5zim0L+ZIQEaRfYQ8POGQjQin 3ygP4mhvU8+cPs9Eu71VUEoQwj/YiB0pIzjwKyA3Ae93r/zRwnRTOFsk8MZjTAJ1y4Q== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b=g33IooBO; 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 5C467606A32E; Fri, 13 Nov 2026 17:23:14 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b=g33IooBO Received: by smtp.kernel.org (Postfix) with ESMTPSA id 095231F000C7; Fri, 13 Nov 2026 17:23:13 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1794590594; bh=yu+/7QT8+MaZWXZZVIB8P8CvxlJRJb/O9cVb+LQf0H8=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=g33IooBOHbwuVw4+CJvEqMxVV5eS7EXFyqZKY9Mk8G9Zwl11KQO4iemM4g7iNru+5 7geZbY6rQslQ9lG8RPUTniXicUyJbFxegmAFFHJlW0JQfeDhiL3YCIKi7QBeJT0i2N 4+v9EFpYSRU3C4FIWsHl7sr9fVOhNHx/W7fDUtPI= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Yifei Gao , Ekansh Gupta , Srinivas Kandagatla , Sasha Levin Subject: [PATCH 6.18 525/686] misc: fastrpc: fix double-free in fastrpc_map_attach() error path Date: Fri, 13 Nov 2026 10:50:58 -0500 Message-ID: <20261113153838.923783189@linuxfoundation.org> X-Mailer: git-send-email 2.56.0 In-Reply-To: <20261113153820.902362109@linuxfoundation.org> References: <20261113153820.902362109@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore 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 6.18-stable review patch. If anyone has any objections, please let me know. ------------------ 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 891f28e933537..9d596f4fd4dcd 100644 --- a/drivers/misc/fastrpc.c +++ b/drivers/misc/fastrpc.c @@ -854,7 +854,7 @@ 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; @@ -877,7 +877,7 @@ 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