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=1794323119; b=dUALxK4ty6y47dE7VFcuhyrfnQeWNDOmx0nsSn69y5nm58DME5MQHn24HGFMclUQwY4e XLv3pM6+Kwtanz308mGI1/WYILmyf5ZYtGJfWXkIjj+O9O6G3KcjOGR7Qlm3s678/9hUh KiyYDf0v+IIuVTtcB1wPuOtMxD4pO7/C7jXzL9kABnMICpIqi+05Gop/jEdkOgFKgecz4 SFSXNvTtGde4JBHHqOYQoAb2vcfnYpYg8f7KB3+ZQhHF0K3CCLDNJgzXHq2DxTCtcugKu HdXjZJcHlibyN2MGOWJjselgxidjsLuH8H7sf25t3JGl/0uK2TdA2W7ItsdAuTZmkwQ== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794323119; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:MIME-Version:Content-Transfer-Encoding; bh=AvjVGl7hP9n6ZVen3Z6llmgS56dtNy5sp1qyOJAKUY4=; b=l6s6TMuHA9fMtFRlAzn0FFxyPkmN33MWPmAD9N3O533iKZ+F+vEvfVwq6pHc58knhwZq DyZMexA4LwYIaYRcimqi/JOhylLN7BrCX+hFGUCJcT4NVdEHFt5TTz3x0HoSKUcOaAAN1 toGJM7SCNsgb0NZmeZ0Ys5auAEmvqBVrd5xRrrnziuo1jqWybZvLpiUdnnbEJKUJM+1fc RwQ6hRpqhboRJQFKhKcwR2/KeETNTDKh0fqjgeSzbTwujGMDpOErRW4MZjsn+ImSbqTPz 26hDTseOzeNX2NbhwT5ja/5NajCYFl9NiMFl6O1azlVFvTLf7srIH77rJ+4TZgZ1uXQ== 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=mHfF5mYP; 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 9B83760A380C for ; Tue, 10 Nov 2026 15:05:19 +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=mHfF5mYP Received: by smtp.kernel.org (Postfix) with ESMTPSA id 723CE1F008BC; Tue, 10 Nov 2026 15:05:18 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1794323119; bh=AvjVGl7hP9n6ZVen3Z6llmgS56dtNy5sp1qyOJAKUY4=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=mHfF5mYPrJOEKrQIr6qttsjeV/4c+Z2ubDx6IcaDaI8JRXIHpYDYttinpFgk9hf2l Ebr5wv/MmACRvtzfSbAoRgkVebIdQ/rhak7q+uyXTr9bA2sCo6sQL4+NXua615Rchg UlDyfKdQc47hb3HJxi7gib+25Jth2eyWAvrBC9GO+ow+89Gqw7kNcJAlRJuee7uhbr v2hT+Rkj9ubGeQKcGJZ8DAtx8sJ2QqjH4HbJoIC3Nutr3Bma3nLJe8YA8nfemTtcKN 6fnQnr4wQt4VdB6Pa2Bn7T9OKJ01jtwOmxLBLbPK5mxT1ICFh4+eU+VJwYP2757kiW Wv4AFXBDDlbeg== From: Sasha Levin To: stable@vger.kernel.org Cc: Yifei Gao , Ekansh Gupta , Srinivas Kandagatla , Greg Kroah-Hartman , Sasha Levin Subject: [PATCH 6.6.y 2/2] misc: fastrpc: fix double-free in fastrpc_map_attach() error path Date: Tue, 10 Nov 2026 10:05:16 -0500 Message-ID: <20261110150509.2034547-2-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20261110150509.2034547-1-sashal@kernel.org> References: <20261107053317-failed-6.6-09fa66ec1b48@kernel.org> <20261110150509.2034547-1-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 18acf810694c9..20ef5822030cf 100644 --- a/drivers/misc/fastrpc.c +++ b/drivers/misc/fastrpc.c @@ -856,7 +856,7 @@ 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; @@ -879,7 +879,7 @@ 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