Messages in this thread | | | Subject | Re: [PATCH] misc: mic: fix a DMA pool free failure | From | Sudeep Dutt <> | Date | Sun, 04 Nov 2018 18:23:33 -0800 |
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On Thu, 2018-10-18 at 14:46 -0500, Wenwen Wang wrote: > In _scif_prog_signal(), a DMA pool is allocated if the MIC Coprocessor is > not X100, i.e., the boolean variable 'x100' is false. This DMA pool will be > freed eventually through the callback function scif_prog_signal_cb() with > the parameter of 'status', which actually points to the start of DMA pool. > Specifically, in scif_prog_signal_cb(), the 'ep' field and the > 'src_dma_addr' field of 'status' are used to free the DMA pool by invoking > dma_pool_free(). Given that 'status' points to the start address of the DMA > pool, both 'status->ep' and 'status->src_dma_addr' are in the DMA pool. And > so, the device has the permission to access them. Even worse, a malicious > device can modify them. As a result, dma_pool_free() will not succeed. > > To avoid the above issue, this patch introduces a new data structure, i.e., > scif_cb_arg, to store the arguments required by the call back function. A > variable 'cb_arg' is allocated in _scif_prog_signal() to pass the > arguments. 'cb_arg' will be freed after dma_pool_free() in > scif_prog_signal_cb(). > > Signed-off-by: Wenwen Wang <wang6495@umn.edu> > --- > drivers/misc/mic/scif/scif_fence.c | 17 +++++++++++++---- > drivers/misc/mic/scif/scif_rma.h | 14 ++++++++++++++ > 2 files changed, 27 insertions(+), 4 deletions(-) > > diff --git a/drivers/misc/mic/scif/scif_fence.c b/drivers/misc/mic/scif/scif_fence.c > index cac3bcc..30f7d9b 100644 > --- a/drivers/misc/mic/scif/scif_fence.c > +++ b/drivers/misc/mic/scif/scif_fence.c > @@ -195,10 +195,11 @@ static inline void *scif_get_local_va(off_t off, struct scif_window *window) > > static void scif_prog_signal_cb(void *arg) > { > - struct scif_status *status = arg; > + struct scif_cb_arg *cb_arg = arg; > > - dma_pool_free(status->ep->remote_dev->signal_pool, status, > - status->src_dma_addr); > + dma_pool_free(cb_arg->ep->remote_dev->signal_pool, cb_arg->status, > + cb_arg->src_dma_addr); > + kfree(cb_arg); > } > > static int _scif_prog_signal(scif_epd_t epd, dma_addr_t dst, u64 val) > @@ -209,6 +210,7 @@ static int _scif_prog_signal(scif_epd_t epd, dma_addr_t dst, u64 val) > bool x100 = !is_dma_copy_aligned(chan->device, 1, 1, 1); > struct dma_async_tx_descriptor *tx; > struct scif_status *status = NULL; > + struct scif_cb_arg *cb_arg = NULL; > dma_addr_t src; > dma_cookie_t cookie; > int err; > @@ -257,8 +259,15 @@ static int _scif_prog_signal(scif_epd_t epd, dma_addr_t dst, u64 val) > goto dma_fail; > } > if (!x100) { > + err = -ENOMEM;
Should err be set to -ENOMEM only if the cb_arg allocation fails?
> + cb_arg = kmalloc(sizeof(*cb_arg), GFP_KERNEL); > + if (!cb_arg) > + goto dma_fail; > + cb_arg->src_dma_addr = src; > + cb_arg->status = status; > + cb_arg->ep = ep; > tx->callback = scif_prog_signal_cb; > - tx->callback_param = status; > + tx->callback_param = cb_arg; > }
cb_arg should be freed if there is a dma_submit_error(..) below in the dma_fail path.
Wenwen, can you please fix these up and resend the patch?
Thanks, Sudeep Dutt
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