From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 4A0BA3624CE; Fri, 24 Apr 2026 17:39:24 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1777052364; cv=none; b=vBNNxvJNPhrnnGon5lSJG97L7OWUeoK1lRrA0HvJ9i2i/n+u6QXIe21gpt0QP4ZGNNeEoA8JACgTaS8U1Fr3Izu9ntGOpP3jRW/M7wGJJ51Vs9TqlAMDx+/iasAHd8EcB4/dWuCEkRwI06qkPDJGoN7shMSge0toZirtxlpkvkE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1777052364; c=relaxed/simple; bh=OJvd+yu2zNHcgfCd9EUwx6/y6bbay/vdg2F/eE+2ajQ=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=A8cB8WvRfLpgy0zyPIbHyrLnavriJwRgqgjKMc9HjPsATNAVvdUPg1gCdazobDvzf668mZfnECmUBCROjOXYrxt7BUQYnO7ywhcQivWcN/WNpwQvszsKANAFysm0pNJgrMha4tGDvqeFshyG6HkkIr5M0o+CYMVzqv4ttPPG178= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=pzX7erb5; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="pzX7erb5" Received: by smtp.kernel.org (Postfix) with ESMTPS id 005F0C2BCB4; Fri, 24 Apr 2026 17:39:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1777052364; bh=OJvd+yu2zNHcgfCd9EUwx6/y6bbay/vdg2F/eE+2ajQ=; h=From:Date:Subject:References:In-Reply-To:To:Cc:Reply-To:From; b=pzX7erb5ARnTZahJ2Rooyfi+qVjydekuVa4AaGYiM7vSPm8xDDURWsPmEMKXtmn0U RYxIuQdKXa974/Xxx70/Y5kffyt72WggyjeouLVlXSWIpQgm7Avo8pFWl9jgFB0cQz hAAcM3l0wGo6fBd24iWXnftyEgWB6CoPPMecFemNfyySBp/7OPKvgeMPAXtIx6fZJK RVAruZJIwA2IJh1QVDNpw7gAe4LOj7jn3wva2Kz0bfH/bV+RMJOjsM8HUfaHTuGmFM IcDixnl3Xz0hCuMDPHUwkA9n33uVoWp6AsthcS8XDClSBROfrPRoI0tGBuWfjVhaN4 JyEbfA+y4Aejg== Received: from aws-us-west-2-korg-lkml-1.web.codeaurora.org (localhost.localdomain [127.0.0.1]) by smtp.lore.kernel.org (Postfix) with ESMTP id E88DFFED3F5; Fri, 24 Apr 2026 17:39:23 +0000 (UTC) From: =?utf-8?q?Nuno_S=C3=A1_via_B4_Relay?= Date: Fri, 24 Apr 2026 18:40:14 +0100 Subject: [PATCH v4 1/4] dmaengine: Fix possible use after free Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 8bit Message-Id: <20260424-dma-dmac-handle-vunmap-v4-1-90f43412fdc0@analog.com> References: <20260424-dma-dmac-handle-vunmap-v4-0-90f43412fdc0@analog.com> In-Reply-To: <20260424-dma-dmac-handle-vunmap-v4-0-90f43412fdc0@analog.com> To: dmaengine@vger.kernel.org, linux-kernel@vger.kernel.org Cc: Lars-Peter Clausen , Vinod Koul , Frank Li X-Mailer: b4 0.15.2 X-Developer-Signature: v=1; a=ed25519-sha256; t=1777052415; l=1250; i=nuno.sa@analog.com; s=20231116; h=from:subject:message-id; bh=J8FQACGd3OeySCyq4xc/4O/tuVwcfMAzSY7wby2Naks=; b=H17/8Zb+644xB77ycJ5potIObMnRnYyuLvr7PBnDpo3PvOfGkHcoaRNSRuwzwQ2Tn8s8zZbRd KuOTEA3ypmOCn6oQUmiqdfkToJ307HXTxnkpo92fXlVzotmAkBiZefo X-Developer-Key: i=nuno.sa@analog.com; a=ed25519; pk=3NQwYA013OUYZsmDFBf8rmyyr5iQlxV/9H4/Df83o1E= X-Endpoint-Received: by B4 Relay for nuno.sa@analog.com/20231116 with auth_id=100 X-Original-From: =?utf-8?q?Nuno_S=C3=A1?= Reply-To: nuno.sa@analog.com From: Nuno Sá In dma_release_channel(), check chan->device->privatecnt after call dma_chan_put(). However, dma_chan_put() call dma_device_put() which could release the last reference of the device if the DMA provider is already gone and hence free it. Fixes it by moving dma_chan_put() after the check. Fixes: 0f571515c332 ("dmaengine: Add privatecnt to revert DMA_PRIVATE property") Signed-off-by: Nuno Sá --- drivers/dma/dmaengine.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/drivers/dma/dmaengine.c b/drivers/dma/dmaengine.c index 405bd2fbb4a3..9049171df857 100644 --- a/drivers/dma/dmaengine.c +++ b/drivers/dma/dmaengine.c @@ -905,11 +905,12 @@ void dma_release_channel(struct dma_chan *chan) mutex_lock(&dma_list_mutex); WARN_ONCE(chan->client_count != 1, "chan reference count %d != 1\n", chan->client_count); - dma_chan_put(chan); /* drop PRIVATE cap enabled by __dma_request_channel() */ if (--chan->device->privatecnt == 0) dma_cap_clear(DMA_PRIVATE, chan->device->cap_mask); + dma_chan_put(chan); + if (chan->slave) { sysfs_remove_link(&chan->dev->device.kobj, DMA_SLAVE_NAME); sysfs_remove_link(&chan->slave->kobj, chan->name); -- 2.54.0