linux-kernel - [PATCH 4/4] misc: fastrpc: Unmap only if buffer is unmapped from DSP

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Message-Id: <20231013122007.174464-5-srinivas.kandagatla@linaro.org>
Date:   Fri, 13 Oct 2023 13:20:07 +0100
From:   srinivas.kandagatla@...aro.org
To:     gregkh@...uxfoundation.org
Cc:     linux-kernel@...r.kernel.org,
        Ekansh Gupta <quic_ekangupt@...cinc.com>,
        stable <stable@...nel.org>,
        Srinivas Kandagatla <srinivas.kandagatla@...aro.org>
Subject: [PATCH 4/4] misc: fastrpc: Unmap only if buffer is unmapped from DSP

From: Ekansh Gupta <quic_ekangupt@...cinc.com>

For unmapping any buffer from kernel, it should first be unmapped
from DSP. In case unmap from DSP request fails, the map should not
be removed from kernel as it might lead to SMMU faults and other
memory issues.

Fixes: 5c1b97c7d7b7 ("misc: fastrpc: add support for FASTRPC_IOCTL_MEM_MAP/UNMAP")
Cc: stable <stable@...nel.org>
Signed-off-by: Ekansh Gupta <quic_ekangupt@...cinc.com>
Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@...aro.org>
---
 drivers/misc/fastrpc.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/drivers/misc/fastrpc.c b/drivers/misc/fastrpc.c
index 3cdc58488db1..1c6c62a7f7f5 100644
--- a/drivers/misc/fastrpc.c
+++ b/drivers/misc/fastrpc.c
@@ -1981,11 +1981,13 @@ static int fastrpc_req_mem_unmap_impl(struct fastrpc_user *fl, struct fastrpc_me
 	sc = FASTRPC_SCALARS(FASTRPC_RMID_INIT_MEM_UNMAP, 1, 0);
 	err = fastrpc_internal_invoke(fl, true, FASTRPC_INIT_HANDLE, sc,
 				      &args[0]);
-	fastrpc_map_put(map);
-	if (err)
+	if (err) {
 		dev_err(dev, "unmmap\tpt fd = %d, 0x%09llx error\n",  map->fd, map->raddr);
+		return err;
+	}
+	fastrpc_map_put(map);
 
-	return err;
+	return 0;
 }
 
 static int fastrpc_req_mem_unmap(struct fastrpc_user *fl, char __user *argp)
-- 
2.25.1