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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 <antonio.argenziano@intel.com>
Testcase: igt/gem_mmap/bad-size
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Antonio Argenziano <antonio.argenziano@intel.com>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Cc: stable@vger.kernel.org
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190314075829.16838-1-chris@chris-wilson.co.uk
(cherry picked from commit 794a11cb67)
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
This commit is contained in:
Chris Wilson 2019-03-14 07:58:29 +00:00 committed by Rodrigo Vivi
parent 65f26e978d
commit 000c4f90e3
1 changed files with 9 additions and 6 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

15
drivers/gpu/drm/i915/i915_gem.c
View File

@ -1734,8 +1734,13 @@ 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,
@ -1749,8 +1754,8 @@ 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))
@ -1768,12 +1773,10 @@ 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;
}