[PATCH 3/4] drm/i915/gem: Replace user_access_begin by user_write_access_begin

From: Christophe Leroy
Date: Tue Feb 04 2020 - 02:38:03 EST


When i915_gem_execbuffer2_ioctl() is using user_access_begin(),
that's only to perform unsafe_put_user() so use
user_write_access_begin() in order to only open write access.

Signed-off-by: Christophe Leroy <christophe.leroy@xxxxxx>
---
drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c | 11 ++++++-----
1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c b/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c
index d5a0f5ae4a8b..f8ebd54fe69c 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c
@@ -1610,14 +1610,14 @@ static int eb_copy_relocations(const struct i915_execbuffer *eb)
* happened we would make the mistake of assuming that the
* relocations were valid.
*/
- if (!user_access_begin(urelocs, size))
+ if (!user_write_access_begin(urelocs, size))
goto end;

for (copied = 0; copied < nreloc; copied++)
unsafe_put_user(-1,
&urelocs[copied].presumed_offset,
end_user);
- user_access_end();
+ user_write_access_end();

eb->exec[i].relocs_ptr = (uintptr_t)relocs;
}
@@ -1625,7 +1625,7 @@ static int eb_copy_relocations(const struct i915_execbuffer *eb)
return 0;

end_user:
- user_access_end();
+ user_write_access_end();
end:
kvfree(relocs);
err = -EFAULT;
@@ -2955,7 +2955,8 @@ i915_gem_execbuffer2_ioctl(struct drm_device *dev, void *data,
* And this range already got effectively checked earlier
* when we did the "copy_from_user()" above.
*/
- if (!user_access_begin(user_exec_list, count * sizeof(*user_exec_list)))
+ if (!user_write_access_begin(user_exec_list,
+ count * sizeof(*user_exec_list)))
goto end;

for (i = 0; i < args->buffer_count; i++) {
@@ -2969,7 +2970,7 @@ i915_gem_execbuffer2_ioctl(struct drm_device *dev, void *data,
end_user);
}
end_user:
- user_access_end();
+ user_write_access_end();
end:;
}

--
2.25.0