In the quest to remove all stack VLA usage from the kernel[1], this moves the buffer off the stack (since it could be as much as 1024 bytes), and uses a new area in the cursor data structure. Additionally adds missed documentation and removes redundant assignments.

[1] https://lkml.kernel.org/r/CA+55aFzCG-zNmZwX4A2FQpadafLfEzK6CC=qPXydAacU1RqZW...

Signed-off-by: Kees Cook keescook@chromium.org --- drivers/video/fbdev/fsl-diu-fb.c | 23 +++++++++++++---------- 1 file changed, 13 insertions(+), 10 deletions(-)

diff --git a/drivers/video/fbdev/fsl-diu-fb.c b/drivers/video/fbdev/fsl-diu-fb.c index 1bfd13cbd4e3..bc9eb8afc313 100644 --- a/drivers/video/fbdev/fsl-diu-fb.c +++ b/drivers/video/fbdev/fsl-diu-fb.c @@ -360,6 +360,10 @@ struct mfb_info { * @ad[]: Area Descriptors for each real AOI * @gamma: gamma color table * @cursor: hardware cursor data + * @blank_cursor: blank cursor for hiding cursor + * @next_cursor: scratch space to build load cursor + * @edid_data: EDID information buffer + * @has_edid: whether or not the EDID buffer is valid * * This data structure must be allocated with 32-byte alignment, so that the * internal fields can be aligned properly. @@ -381,6 +385,8 @@ struct fsl_diu_data { __le16 cursor[MAX_CURS * MAX_CURS] __aligned(32); /* Blank cursor data -- used to hide the cursor */ __le16 blank_cursor[MAX_CURS * MAX_CURS] __aligned(32); + /* Scratch cursor data -- used to build new cursor */ + __le16 next_cursor[MAX_CURS * MAX_CURS] __aligned(32); uint8_t edid_data[EDID_LENGTH]; bool has_edid; } __aligned(32); @@ -1056,13 +1062,17 @@ static int fsl_diu_cursor(struct fb_info *info, struct fb_cursor *cursor) * FB_CUR_SETSHAPE - the cursor bitmask has changed */ if (cursor->set & (FB_CUR_SETSHAPE | FB_CUR_SETCMAP | FB_CUR_SETIMAGE)) { + /* + * Determine the size of the cursor image data. Normally, + * it's 8x16. + */ unsigned int image_size = - DIV_ROUND_UP(cursor->image.width, 8) * cursor->image.height; + DIV_ROUND_UP(cursor->image.width, 8) * + cursor->image.height; unsigned int image_words = DIV_ROUND_UP(image_size, sizeof(uint32_t)); unsigned int bg_idx = cursor->image.bg_color; unsigned int fg_idx = cursor->image.fg_color; - uint8_t buffer[image_size]; uint32_t *image, *source, *mask; uint16_t fg, bg; unsigned int i; @@ -1070,13 +1080,6 @@ static int fsl_diu_cursor(struct fb_info *info, struct fb_cursor *cursor) if (info->state != FBINFO_STATE_RUNNING) return 0;

- /* - * Determine the size of the cursor image data. Normally, - * it's 8x16. - */ - image_size = DIV_ROUND_UP(cursor->image.width, 8) * - cursor->image.height; - bg = ((info->cmap.red[bg_idx] & 0xf8) << 7) | ((info->cmap.green[bg_idx] & 0xf8) << 2) | ((info->cmap.blue[bg_idx] & 0xf8) >> 3) | @@ -1088,7 +1091,7 @@ static int fsl_diu_cursor(struct fb_info *info, struct fb_cursor *cursor) 1 << 15;

/* Use 32-bit operations on the data to improve performance */ - image = (uint32_t *)buffer; + image = (uint32_t *)data->next_cursor; source = (uint32_t *)cursor->image.data; mask = (uint32_t *)cursor->mask;