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drm/amd/display: Don't allow partial copy_from_user

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There is no reason to allow for partial buffers from userspace in our
debugfs. In this particular case callers will zero out the wr_buf but if
callers in the future don't do that we might be looking at corrupt data.

Linus puts it better than I can in
https://lkml.org/lkml/2021/10/26/993

Reviewed-by: Rodrigo Siqueira <Rodrigo.Siqueira@amd.com>
Signed-off-by: Harry Wentland <harry.wentland@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
This commit is contained in:
Harry Wentland 2021-10-27 10:26:33 -04:00 committed by Alex Deucher
parent 7846972880
commit 25a1a08fe7
1 changed files with 4 additions and 6 deletions
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10
drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_debugfs.c
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@ -78,12 +78,10 @@ static int parse_write_buffer_into_params(char *wr_buf, uint32_t wr_buf_size,
wr_buf_ptr = wr_buf;
r = copy_from_user(wr_buf_ptr, buf, wr_buf_size);
/* r is bytes not be copied */
if (r >= wr_buf_size) {
DRM_DEBUG_DRIVER("user data not be read\n");
return -EINVAL;
/* r is bytes not be copied */
if (copy_from_user(wr_buf_ptr, buf, wr_buf_size)) {
DRM_DEBUG_DRIVER("user data could not be read successfully\n");
return -EFAULT;
}
/* check number of parameters. isspace could not differ space and \n */