linux-kernel - [PATCH v1] misc: fastrpc: Fix incorrect DMA mapping unmap request

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Message-ID: <1690180827-20810-1-git-send-email-quic_ekangupt@quicinc.com>
Date:   Mon, 24 Jul 2023 12:10:27 +0530
From:   Ekansh Gupta <quic_ekangupt@...cinc.com>
To:     <srinivas.kandagatla@...aro.org>, <linux-arm-msm@...r.kernel.org>
CC:     Ekansh Gupta <quic_ekangupt@...cinc.com>,
        <ekangupt@....qualcomm.com>, <gregkh@...uxfoundation.org>,
        <linux-kernel@...r.kernel.org>, <fastrpc.upstream@....qualcomm.com>
Subject: [PATCH v1] misc: fastrpc: Fix incorrect DMA mapping unmap request

Scatterlist table is obtained during map create request and the same
table is used for DMA mapping unmap. In case there is any failure
while getting the sg_table, ERR_PTR is returned instead of sg_table.

When the map is getting freed, there is only a non-NULL check of
sg_table which will also be true in case failure was returned instead
of sg_table. This would result in improper unmap request. Add proper
check to avoid bad unmap request.

Signed-off-by: Ekansh Gupta <quic_ekangupt@...cinc.com>
---
 drivers/misc/fastrpc.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/misc/fastrpc.c b/drivers/misc/fastrpc.c
index 9666d28..75da69a 100644
--- a/drivers/misc/fastrpc.c
+++ b/drivers/misc/fastrpc.c
@@ -313,7 +313,7 @@ static void fastrpc_free_map(struct kref *ref)
 
 	map = container_of(ref, struct fastrpc_map, refcount);
 
-	if (map->table) {
+	if (map->table && !IS_ERR(map->table)) {
 		if (map->attr & FASTRPC_ATTR_SECUREMAP) {
 			struct qcom_scm_vmperm perm;
 			int vmid = map->fl->cctx->vmperms[0].vmid;
-- 
2.7.4