From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 B24C24418E4; Mon, 17 Aug 2026 13:58:59 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786975141; cv=none; b=gyoqgClxryKQ6n35YxLfwvwmnAgKGD9bvIWFtQp1UngA7QrGaKJls7+0J0sS2LbZWoM5kbR54Jd10K+QQFWQT01SIau1s2RfKbG4kokzU5I42D4egNDCa5B1RTt58NtsvTT1pEFZsM4IUBtLOETEsP+dy81UkO70JEDWONzNYbY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786975141; c=relaxed/simple; bh=rtGxoi6tjPK8YVIxjVBtj4DCSfOMsIZxyJSfv5sDmlU=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=nLLvQPMe7AgA0QKjYcbB29GjFnPzZFQ/o/SYJ3IJarxC8oRoJwPDXNAheYQQYntplSkccabr7ruYtxxB0LrTyCm+vaQf3l28R7V+KpesulyTxyXC5kTdBopAHE0drZrMem/KkEiQRF5GrDXG1c8f0CjoerUQZJEWR55cSORFWs8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=dN+DpscE; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="dN+DpscE" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 0BD7E1F000E9; Mon, 17 Aug 2026 13:58:58 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1786975139; bh=fWVbQQ/VdoVhbd5aOjuEO5HB41LGk2Hb9bjuZ1QWPlk=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=dN+DpscEzLzkOVpxoOUxIre+v8FPHUu/SmuvOg/OMzGchU7wpAmbR7uwA5k64S6yF R3OcT3CJvgsRqP1AW5bt2IdEbmH2k57loWTOcuYA7pYdeaXhVxVRZ1nm+zSzzS/3L4 /6g36Eoad5MBIMa51yT8ZsIBcqD2F+PE2oa2m8w0= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, stable@kernel.org, Dmitry Baryshkov , Ekansh Gupta , Jianping Li , Srinivas Kandagatla Subject: [PATCH 6.18 176/250] misc: fastrpc: Remove buffer from list prior to unmap operation Date: Mon, 17 Aug 2026 15:32:17 +0200 Message-ID: <20260817132543.795167129@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260817132536.466235697@linuxfoundation.org> References: <20260817132536.466235697@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Ekansh Gupta commit 6102ceb4eab845743ee57acd3863fbd06e93c927 upstream. fastrpc_req_munmap_impl() is called to unmap any buffer. The buffer is getting removed from the list after it is unmapped from DSP. This can create potential race conditions if multiple threads invoke unmap concurrently, where one thread may remove the entry from the list while another thread's unmap operation is still ongoing. Fix this by removing the buffer entry from the list before calling the unmap operation. If the unmap fails, the entry is re-added to the list so that userspace can retry the unmap, or alternatively, the buffer will be cleaned up during device release when the DSP process is torn down and all DSP-side mappings are freed along with remaining buffers in the list. Fixes: 2419e55e532de ("misc: fastrpc: add mmap/unmap support") Cc: stable@kernel.org Reviewed-by: Dmitry Baryshkov Signed-off-by: Ekansh Gupta Signed-off-by: Jianping Li Signed-off-by: Srinivas Kandagatla Link: https://patch.msgid.link/20260724223342.629168-3-srini@kernel.org Signed-off-by: Greg Kroah-Hartman Signed-off-by: Greg Kroah-Hartman --- drivers/misc/fastrpc.c | 14 ++++++++++---- 1 file changed, 10 insertions(+), 4 deletions(-) --- a/drivers/misc/fastrpc.c +++ b/drivers/misc/fastrpc.c @@ -1858,9 +1858,6 @@ static int fastrpc_req_munmap_impl(struc &args[0]); if (!err) { dev_dbg(dev, "unmmap\tpt 0x%09lx OK\n", buf->raddr); - spin_lock(&fl->lock); - list_del(&buf->node); - spin_unlock(&fl->lock); fastrpc_buf_free(buf); } else { dev_err(dev, "unmmap\tpt 0x%09lx ERROR\n", buf->raddr); @@ -1874,6 +1871,7 @@ static int fastrpc_req_munmap(struct fas struct fastrpc_buf *buf = NULL, *iter, *b; struct fastrpc_req_munmap req; struct device *dev = fl->sctx->dev; + int err; if (copy_from_user(&req, argp, sizeof(req))) return -EFAULT; @@ -1881,6 +1879,7 @@ static int fastrpc_req_munmap(struct fas spin_lock(&fl->lock); list_for_each_entry_safe(iter, b, &fl->mmaps, node) { if ((iter->raddr == req.vaddrout) && (iter->size == req.size)) { + list_del(&iter->node); buf = iter; break; } @@ -1893,7 +1892,14 @@ static int fastrpc_req_munmap(struct fas return -EINVAL; } - return fastrpc_req_munmap_impl(fl, buf); + err = fastrpc_req_munmap_impl(fl, buf); + if (err) { + spin_lock(&fl->lock); + list_add_tail(&buf->node, &fl->mmaps); + spin_unlock(&fl->lock); + } + + return err; } static int fastrpc_req_mmap(struct fastrpc_user *fl, char __user *argp)