From: Paul Mundt Date: Mon, 5 Mar 2007 08:30:31 +0000 (-0800) Subject: [PATCH] fb: sm501fb off-by-1 sysfs store X-Git-Tag: firefly_0821_release~30833 X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=1f2b69f9bdce8461341e5fb864568a2ee90079c8;p=firefly-linux-kernel-4.4.55.git [PATCH] fb: sm501fb off-by-1 sysfs store Currently sm501fb_crtsrc_store() won't allow the routing to be changed via echos from userspace in to the sysfs file. The reason for this is that the strnicmp() for both heads uses a sizeof() for the string length, which ends up being strlen() + 1 (\0 in the normal case, but the echo gives a newline, which is where the issue occurs), this then causes a mismatch and subsequently bails with the -EINVAL. In addition to this, the hardcoded lengths were then used for the store length that was returned, which ended up being erroneous and resulting in a write error. There's also no point in returning anything but the full length since it will -EINVAL out on a mismatch well before then anyways. sizeof("string") is great for making sure you have space in your buffer, but rather less so for string comparisons :-) Signed-off-by: Paul Mundt Acked-by: Ben Dooks Cc: "Antonino A. Daplas" Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- diff --git a/drivers/video/sm501fb.c b/drivers/video/sm501fb.c index 58c0ac733db9..0a44c44672c8 100644 --- a/drivers/video/sm501fb.c +++ b/drivers/video/sm501fb.c @@ -1074,9 +1074,9 @@ static ssize_t sm501fb_crtsrc_store(struct device *dev, if (len < 1) return -EINVAL; - if (strnicmp(buf, "crt", sizeof("crt")) == 0) + if (strnicmp(buf, "crt", 3) == 0) head = HEAD_CRT; - else if (strnicmp(buf, "panel", sizeof("panel")) == 0) + else if (strnicmp(buf, "panel", 5) == 0) head = HEAD_PANEL; else return -EINVAL; @@ -1098,7 +1098,7 @@ static ssize_t sm501fb_crtsrc_store(struct device *dev, writel(ctrl, info->regs + SM501_DC_CRT_CONTROL); sm501fb_sync_regs(info); - return (head == HEAD_CRT) ? 3 : 5; + return len; } /* Prepare the device_attr for registration with sysfs later */