From b7fd68ab1538e3adb665670414bea440f399fda9 Mon Sep 17 00:00:00 2001 From: "Matthew Wilcox (Oracle)" Date: Thu, 5 Oct 2023 14:56:47 +0100 Subject: [PATCH] drm: Do not overrun array in drm_gem_get_pages() If the shared memory object is larger than the DRM object that it backs, we can overrun the page array. Limit the number of pages we install from each folio to prevent this. Signed-off-by: "Matthew Wilcox (Oracle)" Reported-by: Oleksandr Natalenko Tested-by: Oleksandr Natalenko Link: https://lore.kernel.org/lkml/13360591.uLZWGnKmhe@natalenko.name/ Fixes: 3291e09a4638 ("drm: convert drm_gem_put_pages() to use a folio_batch") Cc: stable@vger.kernel.org # 6.5.x Signed-off-by: Maxime Ripard Link: https://patchwork.freedesktop.org/patch/msgid/20231005135648.2317298-1-willy@infradead.org --- drivers/gpu/drm/drm_gem.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/drivers/gpu/drm/drm_gem.c b/drivers/gpu/drm/drm_gem.c index 6129b89..44a948b 100644 --- a/drivers/gpu/drm/drm_gem.c +++ b/drivers/gpu/drm/drm_gem.c @@ -540,7 +540,7 @@ struct page **drm_gem_get_pages(struct drm_gem_object *obj) struct page **pages; struct folio *folio; struct folio_batch fbatch; - int i, j, npages; + long i, j, npages; if (WARN_ON(!obj->filp)) return ERR_PTR(-EINVAL); @@ -564,11 +564,13 @@ struct page **drm_gem_get_pages(struct drm_gem_object *obj) i = 0; while (i < npages) { + long nr; folio = shmem_read_folio_gfp(mapping, i, mapping_gfp_mask(mapping)); if (IS_ERR(folio)) goto fail; - for (j = 0; j < folio_nr_pages(folio); j++, i++) + nr = min(npages - i, folio_nr_pages(folio)); + for (j = 0; j < nr; j++, i++) pages[i] = folio_file_page(folio, i); /* Make sure shmem keeps __GFP_DMA32 allocated pages in the -- 2.7.4