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=1794322346; b=cwX7DEoIR39+2lLUwQo9Ud9zr/EOtfe5m9KaOOjK+/FiaiEYkLGFC7F27okUg5R4pZw/ 9WjY2er1KZsGuF9KlWB3p3+IjbzuneC8RPZmaIXCuwDpHjPdIqmE4dAHR1zSERbr1CSSN LadUcS9p2TOGMuA3g3QBcvBIQKtbdhQw9Bn59LJY2GS3nS2bwWw0p3URXCDpwn/q/Fx9T 1YH0yn5kC0wPSxMC9qV8iqTXczI6nmyntxL7vfCMi4sCZ5FvkL5QqZSsN5JMOHEWQIjmc sdYCIr9fD1oOGbVYB8z8vqaW/TsUU+KnIMe+5+iJQ2Td6gmXpTRn4TSU2UGL2IF/Wcg== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794322346; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:MIME-Version:Content-Transfer-Encoding; bh=WEi0OBPz0WhzdtOPhVd3eOIpfuGhYQ8+zh669kK+Wao=; b=rGgpp4CwtAuIb6yP3dSNp2ju9+hwBxZTkzxa6F6rHbVs314rR3POpJc/Z4+kiQpwXJuT awGPT3td2kHQDYsZgzaG32GVOExEyEXRjOqf7ZFPW9hGAMdBshXiFhu2I8YwdgbWhfcua cx4pVMi2O1Xz46ES+Z3gDKCLpGfEXf089Nt9ytAJPTt5XwfzD0En/OPjtEbN+b2L+cnks 3L9il2e9WstxFI1N43Vmq2AD65WUvWgw6YaE7TjN0BYx8f4RB9N+0rUKUKRek57mjAmsz KbWMyyzwxJuEt/Okw9eBqGGznjkx+6MhtX47Q2Rs7DoTbkqja39zGrOr8vIYWiMgjSw== 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="J+GuAu/+"; 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 2297E60A2600 for ; Tue, 10 Nov 2026 14:52:26 +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=J+GuAu/+ Received: by smtp.kernel.org (Postfix) with ESMTPSA id 28D601F008A2; Tue, 10 Nov 2026 14:52:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1794322345; bh=WEi0OBPz0WhzdtOPhVd3eOIpfuGhYQ8+zh669kK+Wao=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=J+GuAu/+y6Bnu0kJO8pyb35iJct9HtmwiBoZ97h+zx7eAJKot4jDUUMa38wkA7VV0 mG8ox2HcDiEHw6s6wAjmXhjVB8NHtuvnWaWr0b7K71QvHIOIRSE0mXPu0gqzQimeSD IURaXbowxlbjaqeqRbRtQM4YZZ/RIWPNwpduQzPZYCmV4u9vRZa7+K6mjvGN8DOBbX B1iOdKN42BVSokqM7TYKA3BBnb9n/1ReVQK3ZGw1dOa4SJQJ3G/zFVmPw6APCuXQL7 ZFVS262XwY1gQg74MLdZAV+IUWDbqbyOU1p4/kC7aPkPYhuJLyOlDaBRvHFPXjJtG0 +SavMiEpEvnaA== From: Sasha Levin To: stable@vger.kernel.org Cc: Yifei Gao , Ekansh Gupta , Srinivas Kandagatla , Greg Kroah-Hartman , Sasha Levin Subject: [PATCH 6.18.y 2/2] misc: fastrpc: fix double-free in fastrpc_map_attach() error path Date: Tue, 10 Nov 2026 09:52:22 -0500 Message-ID: <20261110145217.1998136-2-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20261110145217.1998136-1-sashal@kernel.org> References: <20261107050955-failed-6.18-09fa66ec1b48@kernel.org> <20261110145217.1998136-1-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 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