linux-kernel - [PATCH] ksmbd: smbd: fix dma_unmap

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Message-ID: <20260109103840.55252-2-fourier.thomas@gmail.com>
Date: Fri,  9 Jan 2026 11:38:39 +0100
From: Thomas Fourier <fourier.thomas@...il.com>
To: 
Cc: Thomas Fourier <fourier.thomas@...il.com>,
	stable@...r.kernel.org,
	Namjae Jeon <linkinjeon@...nel.org>,
	Steve French <smfrench@...il.com>,
	Sergey Senozhatsky <senozhatsky@...omium.org>,
	Tom Talpey <tom@...pey.com>,
	Hyunchul Lee <hyc.lee@...il.com>,
	Ronnie Sahlberg <lsahlber@...hat.com>,
	linux-cifs@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH] ksmbd: smbd: fix dma_unmap_sg() nents

The dma_unmap_sg() functions should be called with the same nents as the
dma_map_sg(), not the value the map function returned.

Fixes: 0626e6641f6b ("cifsd: add server handler for central processing and tranport layers")
Cc: <stable@...r.kernel.org>
Signed-off-by: Thomas Fourier <fourier.thomas@...il.com>
---
 fs/smb/server/transport_rdma.c | 15 +++++++--------
 1 file changed, 7 insertions(+), 8 deletions(-)

diff --git a/fs/smb/server/transport_rdma.c b/fs/smb/server/transport_rdma.c
index f585359684d4..8620690aa2ec 100644
--- a/fs/smb/server/transport_rdma.c
+++ b/fs/smb/server/transport_rdma.c
@@ -1353,14 +1353,12 @@ static int get_sg_list(void *buf, int size, struct scatterlist *sg_list, int nen
 
 static int get_mapped_sg_list(struct ib_device *device, void *buf, int size,
 			      struct scatterlist *sg_list, int nentries,
-			      enum dma_data_direction dir)
+			      enum dma_data_direction dir, int *npages)
 {
-	int npages;
-
-	npages = get_sg_list(buf, size, sg_list, nentries);
-	if (npages < 0)
+	*npages = get_sg_list(buf, size, sg_list, nentries);
+	if (*npages < 0)
 		return -EINVAL;
-	return ib_dma_map_sg(device, sg_list, npages, dir);
+	return ib_dma_map_sg(device, sg_list, *npages, dir);
 }
 
 static int post_sendmsg(struct smbdirect_socket *sc,
@@ -1431,12 +1429,13 @@ static int smb_direct_post_send_data(struct smbdirect_socket *sc,
 	for (i = 0; i < niov; i++) {
 		struct ib_sge *sge;
 		int sg_cnt;
+		int npages;
 
 		sg_init_table(sg, SMBDIRECT_SEND_IO_MAX_SGE - 1);
 		sg_cnt = get_mapped_sg_list(sc->ib.dev,
 					    iov[i].iov_base, iov[i].iov_len,
 					    sg, SMBDIRECT_SEND_IO_MAX_SGE - 1,
-					    DMA_TO_DEVICE);
+					    DMA_TO_DEVICE, &npages);
 		if (sg_cnt <= 0) {
 			pr_err("failed to map buffer\n");
 			ret = -ENOMEM;
@@ -1444,7 +1443,7 @@ static int smb_direct_post_send_data(struct smbdirect_socket *sc,
 		} else if (sg_cnt + msg->num_sge > SMBDIRECT_SEND_IO_MAX_SGE) {
 			pr_err("buffer not fitted into sges\n");
 			ret = -E2BIG;
-			ib_dma_unmap_sg(sc->ib.dev, sg, sg_cnt,
+			ib_dma_unmap_sg(sc->ib.dev, sg, npages,
 					DMA_TO_DEVICE);
 			goto err;
 		}
-- 
2.43.0