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[PATCH] fb: sm501fb off-by-1 sysfs store

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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 <lethal@linux-sh.org>
Acked-by: Ben Dooks <ben-linux@fluff.org>
Cc: "Antonino A. Daplas" <adaplas@pol.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Paul Mundt 2007-03-05 00:30:31 -08:00 committed by Linus Torvalds
parent 69f7c0a1be
commit 1f2b69f9bd
1 changed files with 3 additions and 3 deletions
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6
drivers/video/sm501fb.c
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@ -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 */