From: Ioan Nicu <ioan.nicu.ext@xxxxxxxxx> Subject: rapidio: fix rio_dma_transfer error handling Some of the mport_dma_req structure members were initialized late inside the do_dma_request() function, just before submitting the request to the dma engine. But we have some error branches before that. In case of such an error, the code would return on the error path and trigger the calling of dma_req_free() with a req structure which is not completely initialized. This causes a NULL pointer dereference in dma_req_free(). This patch fixes these error branches by making sure that all necessary mport_dma_req structure members are initialized in rio_dma_transfer() immediately after the request structure gets allocated. Link: http://lkml.kernel.org/r/20180412150605.GA31409@xxxxxxxxx Fixes: bbd876adb8c72 ("rapidio: use a reference count for struct mport_dma_req") Signed-off-by: Ioan Nicu <ioan.nicu.ext@xxxxxxxxx> Tested-by: Alexander Sverdlin <alexander.sverdlin@xxxxxxxxx> Acked-by: Alexandre Bounine <alex.bou9@xxxxxxxxx> Cc: Barry Wood <barry.wood@xxxxxxx> Cc: Matt Porter <mporter@xxxxxxxxxxxxxxxxxxx> Cc: Christophe JAILLET <christophe.jaillet@xxxxxxxxxx> Cc: Logan Gunthorpe <logang@xxxxxxxxxxxx> Cc: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> Cc: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxx> Cc: Frank Kunz <frank.kunz@xxxxxxxxx> Cc: <stable@xxxxxxxxxxxxxxx> [4.6+] Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- drivers/rapidio/devices/rio_mport_cdev.c | 19 +++++++++---------- 1 file changed, 9 insertions(+), 10 deletions(-) diff -puN drivers/rapidio/devices/rio_mport_cdev.c~rapidio-fix-rio_dma_transfer-error-handling drivers/rapidio/devices/rio_mport_cdev.c --- a/drivers/rapidio/devices/rio_mport_cdev.c~rapidio-fix-rio_dma_transfer-error-handling +++ a/drivers/rapidio/devices/rio_mport_cdev.c @@ -740,10 +740,7 @@ static int do_dma_request(struct mport_d tx->callback = dma_xfer_callback; tx->callback_param = req; - req->dmach = chan; - req->sync = sync; req->status = DMA_IN_PROGRESS; - init_completion(&req->req_comp); kref_get(&req->refcount); cookie = dmaengine_submit(tx); @@ -831,13 +828,20 @@ rio_dma_transfer(struct file *filp, u32 if (!req) return -ENOMEM; - kref_init(&req->refcount); - ret = get_dma_channel(priv); if (ret) { kfree(req); return ret; } + chan = priv->dmach; + + kref_init(&req->refcount); + init_completion(&req->req_comp); + req->dir = dir; + req->filp = filp; + req->priv = priv; + req->dmach = chan; + req->sync = sync; /* * If parameter loc_addr != NULL, we are transferring data from/to @@ -925,11 +929,6 @@ rio_dma_transfer(struct file *filp, u32 xfer->offset, xfer->length); } - req->dir = dir; - req->filp = filp; - req->priv = priv; - chan = priv->dmach; - nents = dma_map_sg(chan->device->dev, req->sgt.sgl, req->sgt.nents, dir); if (nents == 0) { _