From 794a11cb67201ad1bb61af510bb8460280feb3f3 Mon Sep 17 00:00:00 2001 From: Chris Wilson Date: Thu, 14 Mar 2019 07:58:29 +0000 Subject: [PATCH] drm/i915: Sanity check mmap length against object size We assumed that vm_mmap() would reject an attempt to mmap past the end of the filp (our object), but we were wrong. Applications that tried to use the mmap beyond the end of the object would be greeted by a SIGBUS. After this patch, those applications will be told about the error on creating the mmap, rather than at a random moment on later access. Reported-by: Antonio Argenziano Testcase: igt/gem_mmap/bad-size Signed-off-by: Chris Wilson Cc: Antonio Argenziano Cc: Joonas Lahtinen Cc: Tvrtko Ursulin Cc: stable@vger.kernel.org Reviewed-by: Tvrtko Ursulin Reviewed-by: Joonas Lahtinen Link: https://patchwork.freedesktop.org/patch/msgid/20190314075829.16838-1-chris@chris-wilson.co.uk --- drivers/gpu/drm/i915/i915_gem.c | 15 +++++++++------ 1 file changed, 9 insertions(+), 6 deletions(-) diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c index b38c9531b5e8..b7086c8d4726 100644 --- a/drivers/gpu/drm/i915/i915_gem.c +++ b/drivers/gpu/drm/i915/i915_gem.c @@ -1639,8 +1639,13 @@ i915_gem_mmap_ioctl(struct drm_device *dev, void *data, * pages from. */ if (!obj->base.filp) { - i915_gem_object_put(obj); - return -ENXIO; + addr = -ENXIO; + goto err; + } + + if (range_overflows(args->offset, args->size, (u64)obj->base.size)) { + addr = -EINVAL; + goto err; } addr = vm_mmap(obj->base.filp, 0, args->size, @@ -1654,8 +1659,8 @@ i915_gem_mmap_ioctl(struct drm_device *dev, void *data, struct vm_area_struct *vma; if (down_write_killable(&mm->mmap_sem)) { - i915_gem_object_put(obj); - return -EINTR; + addr = -EINTR; + goto err; } vma = find_vma(mm, addr); if (vma && __vma_matches(vma, obj->base.filp, addr, args->size)) @@ -1673,12 +1678,10 @@ i915_gem_mmap_ioctl(struct drm_device *dev, void *data, i915_gem_object_put(obj); args->addr_ptr = (u64)addr; - return 0; err: i915_gem_object_put(obj); - return addr; } -- 2.30.2