Re: [PATCH] fbdev: colormap fixes
From: Jon Smirl <hidden>
Date: 2005-07-28 19:33:50
Also in:
lkml
Subsystem:
framebuffer layer, the rest · Maintainers:
Helge Deller, Linus Torvalds
Do we want to apply this patch now to get rid of the buffer overflow hole? Then we can take our time and work out a better solution. -- Jon Smirl jonsmirl@gmail.com Fix a buffer overflow vunerabilty in previous cmap patch signed-off-by: Jon Smirl <redacted>
diff --git a/drivers/video/fbsysfs.c b/drivers/video/fbsysfs.c
--- a/drivers/video/fbsysfs.c
+++ b/drivers/video/fbsysfs.c@@ -244,15 +244,15 @@ static ssize_t show_virtual(struct class /* Format for cmap is "%02x%c%4x%4x%4x\n" */ /* %02x entry %c transp %4x red %4x blue %4x green \n */ -/* 255 rows at 16 chars equals 4096 */ -/* PAGE_SIZE can be 4096 or larger */ +/* 256 rows at 16 chars equals 4096, the normal page size */ +/* the code will automatically adjust for different page sizes */ static ssize_t store_cmap(struct class_device *class_device, const char *buf, size_t count) { struct fb_info *fb_info = (struct fb_info *)class_get_devdata(class_device); int rc, i, start, length, transp = 0; - if ((count > 4096) || ((count % 16) != 0) || (PAGE_SIZE < 4096)) + if ((count > PAGE_SIZE) || ((count % 16) != 0)) return -EINVAL; if (!fb_info->fbops->fb_setcolreg && !fb_info->fbops->fb_setcmap)
@@ -317,18 +317,18 @@ static ssize_t show_cmap(struct class_de !fb_info->cmap.green) return -EINVAL; - if (PAGE_SIZE < 4096) + if (fb_info->cmap.len > PAGE_SIZE / 16) return -EINVAL; /* don't mess with the format, the buffer is PAGE_SIZE */ - /* 255 entries at 16 chars per line equals 4096 = PAGE_SIZE */ + /* 256 entries at 16 chars per line equals 4096 = PAGE_SIZE */ for (i = 0; i < fb_info->cmap.len; i++) { - sprintf(&buf[ i * 16], "%02x%c%4x%4x%4x\n", i + fb_info->cmap.start, + snprintf(&buf[ i * 16], PAGE_SIZE - i * 16, "%02x%c%4x%4x%4x\n", i + fb_info->cmap.start, ((fb_info->cmap.transp && fb_info->cmap.transp[i]) ? '*' : ' '), fb_info->cmap.red[i], fb_info->cmap.blue[i], fb_info->cmap.green[i]); } - return 4096; + return 16 * fb_info->cmap.len; } static ssize_t store_blank(struct class_device *class_device, const char * buf, -------------------------------------------------------
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