From 74446b63dd4ec386fc5de554d5c4a3536096072f Mon Sep 17 00:00:00 2001 From: Anatolij Gustschin Date: Mon, 21 Feb 2011 21:33:29 +0100 Subject: [PATCH] cfb_console: fix RLE bitmap drawing code There seems to be tools producing incorrect 'end of bitmap data' markers '0100' in a RLE bitmap. Drawing such bitmaps can result in overwriting memory above the frame buffer. E.g. on MPC5121e based boards this memory can contain U-Boot environment. We may not rely on the correct end of bitmap data marker 0001 only, but also have to check whether we are going to draw a valid frame buffer scan line. The patch provides a fix by maintaining a pixel counter which is incremented by the amount of pixels we are going to draw. If the counter exceeds frame buffer pixels limit we stop the drawing with the error message. Reported-by: Michael Weiss Signed-off-by: Anatolij Gustschin Tested-by: Anatolij Gustschin --- drivers/video/cfb_console.c | 19 +++++++++++++++---- 1 file changed, 15 insertions(+), 4 deletions(-) diff --git a/drivers/video/cfb_console.c b/drivers/video/cfb_console.c index dd849c2dc1..b427c84877 100644 --- a/drivers/video/cfb_console.c +++ b/drivers/video/cfb_console.c @@ -882,6 +882,8 @@ static int display_rle8_bitmap (bmp_image_t *img, int xoff, int yoff, struct palette p[256]; bmp_color_table_entry_t cte; int green_shift, red_off; + int limit = VIDEO_COLS * VIDEO_ROWS; + int pixels = 0; x = 0; y = __le32_to_cpu(img->header.height) - 1; @@ -962,6 +964,10 @@ static int display_rle8_bitmap (bmp_image_t *img, int xoff, int yoff, /* unencoded run */ cnt = bm[1]; runlen = cnt; + pixels += cnt; + if (pixels > limit) + goto error; + bm += 2; if (y < height) { if (x >= width) { @@ -970,7 +976,6 @@ static int display_rle8_bitmap (bmp_image_t *img, int xoff, int yoff, } if (x + runlen > width) cnt = width - x; - draw_bitmap (&fbp, bm, p, cnt, 0); x += runlen; } @@ -982,9 +987,13 @@ next_run: break; default: /* encoded run */ + cnt = bm[0]; + runlen = cnt; + pixels += cnt; + if (pixels > limit) + goto error; + if (y < height) { /* only draw into visible area */ - cnt = bm[0]; - runlen = cnt; if (x >= width) { x += runlen; bm += 2; @@ -992,7 +1001,6 @@ next_run: } if (x + runlen > width) cnt = width - x; - draw_bitmap (&fbp, bm, p, cnt, 1); x += runlen; } @@ -1001,6 +1009,9 @@ next_run: } } return 0; +error: + printf("Error: Too much encoded pixel data, validate your bitmap\n"); + return -1; } #endif -- 2.39.5