From 9b399ee577e11bd8b9425e279029c65029800edc Mon Sep 17 00:00:00 2001 From: "T.J. Mercier" Date: Fri, 30 Aug 2024 19:26:26 +0000 Subject: [PATCH] UPSTREAM: dma-buf: heaps: Fix off-by-one in CMA heap fault handler commit ea5ff5d351b520524019f7ff7f9ce418de2dad87 upstream. 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. Bug: 363259128 Reported-by: Xingyu Jin Fixes: a5d2d29e24be ("dma-buf: heaps: Move heap-helper logic into the cma_heap implementation") Cc: stable@vger.kernel.org # Applicable >= 5.10. Needs adjustments only for 5.10. Signed-off-by: T.J. Mercier Acked-by: John Stultz Signed-off-by: Sumit Semwal Link: https://patchwork.freedesktop.org/patch/msgid/20240830192627.2546033-1-tjmercier@google.com Signed-off-by: Greg Kroah-Hartman (cherry picked from commit 79cce5e81d20fa9ad553be439d665ac3302d3c95) Signed-off-by: Lee Jones Change-Id: Ifc9c940e0a3cd721d29c783753b0dfd13a8aafc6 --- 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 511d678ec..5f765b2ce 100755 --- a/drivers/dma-buf/heaps/cma_heap.c +++ b/drivers/dma-buf/heaps/cma_heap.c @@ -167,7 +167,7 @@ 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; vmf->page = buffer->pages[vmf->pgoff];