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drm/gem-shmem: Test for existence of page in mmap fault handler

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Not having a page pointer in the mmap fault handler is an error. Test
for this situation and return VM_FAULT_SIGBUS if so. Also replace several
lookups of the page with a local variable.

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Boris Brezillon <boris.brezillon@collabora.com>
Link: https://patch.msgid.link/20260227114509.165572-3-tzimmermann@suse.de
This commit is contained in:
Thomas Zimmermann 2026-02-27 12:42:07 +01:00
parent 6b1697f23c
commit cd40c12a9e
1 changed files with 12 additions and 12 deletions
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24
drivers/gpu/drm/drm_gem_shmem_helper.c
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@ -574,31 +574,31 @@ static vm_fault_t drm_gem_shmem_fault(struct vm_fault *vmf)
{
struct vm_area_struct *vma = vmf->vma;
struct drm_gem_object *obj = vma->vm_private_data;
struct drm_device *dev = obj->dev;
struct drm_gem_shmem_object *shmem = to_drm_gem_shmem_obj(obj);
loff_t num_pages = obj->size >> PAGE_SHIFT;
vm_fault_t ret;
vm_fault_t ret = VM_FAULT_SIGBUS;
struct page **pages = shmem->pages;
pgoff_t page_offset;
pgoff_t page_offset = vmf->pgoff - vma->vm_pgoff; /* page offset within VMA */
struct page *page;
unsigned long pfn;
/* Offset to faulty address in the VMA. */
page_offset = vmf->pgoff - vma->vm_pgoff;
dma_resv_lock(obj->resv, NULL);
if (page_offset >= num_pages ||
drm_WARN_ON_ONCE(obj->dev, !shmem->pages) ||
shmem->madv < 0) {
ret = VM_FAULT_SIGBUS;
if (page_offset >= num_pages || drm_WARN_ON_ONCE(dev, !shmem->pages) ||
shmem->madv < 0)
goto out;
}
if (drm_gem_shmem_try_map_pmd(vmf, vmf->address, pages[page_offset])) {
page = pages[page_offset];
if (drm_WARN_ON_ONCE(dev, !page))
goto out;
if (drm_gem_shmem_try_map_pmd(vmf, vmf->address, page)) {
ret = VM_FAULT_NOPAGE;
goto out;
}
pfn = page_to_pfn(pages[page_offset]);
pfn = page_to_pfn(page);
ret = vmf_insert_pfn(vma, vmf->address, pfn);
out: