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authorMatthew Wilcox (Oracle) <willy@infradead.org>2023-10-05 14:56:47 +0100
committerMaxime Ripard <mripard@kernel.org>2023-10-12 10:44:06 +0200
commitb7fd68ab1538e3adb665670414bea440f399fda9 (patch)
tree5c23ec8ae85f915b2f05a40a9e1f9cb85e42f958
parent2b7947bd32e243c52870d54141d3b4ea6775e63d (diff)
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)" <willy@infradead.org> Reported-by: Oleksandr Natalenko <oleksandr@natalenko.name> Tested-by: Oleksandr Natalenko <oleksandr@natalenko.name> 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 <mripard@kernel.org> Link: https://patchwork.freedesktop.org/patch/msgid/20231005135648.2317298-1-willy@infradead.org
-rw-r--r--drivers/gpu/drm/drm_gem.c6
1 files changed, 4 insertions, 2 deletions
diff --git a/drivers/gpu/drm/drm_gem.c b/drivers/gpu/drm/drm_gem.c
index 6129b89bb366..44a948b80ee1 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