Messages in this thread | | | From | Wenwen Wang <> | Date | Tue, 4 Dec 2018 08:35:00 -0600 | Subject | Re: [PATCH] misc: mic: fix a DMA pool free failure |
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On Sun, Nov 4, 2018 at 8:05 PM Sudeep Dutt <sudeep.dutt@intel.com> wrote: > > 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?
Sure, will fix the issues and resubmit the patch. Thanks!
Wenwen
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