On Fri, Aug 30, 2024 at 12:26 PM T.J. Mercier <tjmercier@xxxxxxxxxx> wrote: > > Until VM_DONTEXPAND was added in commit 1c1914d6e8c6 ("dma-buf: heaps: > Don't track CMA dma-buf pages under RssFile") it was possible to obtain > a mapping larger than the buffer size via mremap and bypass the overflow > check in dma_buf_mmap_internal. When using such a mapping to attempt to > fault past the end of the buffer, the CMA heap fault handler also checks > the fault offset against the buffer size, but gets the boundary wrong by > 1. Fix the boundary check so that we don't read off the end of the pages > array and insert an arbitrary page in the mapping. > > Reported-by: Xingyu Jin <xingyuj@xxxxxxxxxx> > Fixes: a5d2d29e24be ("dma-buf: heaps: Move heap-helper logic into the cma_heap implementation") > Cc: stable@xxxxxxxxxxxxxxx # Applicable >= 5.10. Needs adjustments only for 5.10. > Signed-off-by: T.J. Mercier <tjmercier@xxxxxxxxxx> > --- > drivers/dma-buf/heaps/cma_heap.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/dma-buf/heaps/cma_heap.c b/drivers/dma-buf/heaps/cma_heap.c > index c384004b918e..93be88b805fe 100644 > --- a/drivers/dma-buf/heaps/cma_heap.c > +++ b/drivers/dma-buf/heaps/cma_heap.c > @@ -165,7 +165,7 @@ static vm_fault_t cma_heap_vm_fault(struct vm_fault *vmf) > struct vm_area_struct *vma = vmf->vma; > struct cma_heap_buffer *buffer = vma->vm_private_data; > > - if (vmf->pgoff > buffer->pagecount) > + if (vmf->pgoff >= buffer->pagecount) > return VM_FAULT_SIGBUS; Thanks for fixing this! (And thanks to Xingyu Jin for catching it!) Acked-by: John Stultz <jstultz@xxxxxxxxxx> thanks -john