Messages in this thread | | | Date | Thu, 21 May 2015 18:14:23 -0400 | From | Tejun Heo <> | Subject | Re: [PATCH] fs: sysfs: don't pass count == 0 to bin file readers |
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Hello,
On Fri, May 22, 2015 at 12:21:16AM +0300, Vladimir Zapolskiy wrote: > If count == 0 bytes are requested by a reader, sysfs_kf_bin_read() > deliberately returns 0 without passing a potentially harmful value to > some externally defined underlying battr->read() function. > > However in case of (pos == size && count) the next clause always sets > count to 0 and this value is handed over to battr->read(). > > The change intends to make obsolete (and remove later) a redundant > sanity check in battr->read(), if it is present, or add more > protection to struct bin_attribute users, who does not care about > input arguments. > > Signed-off-by: Vladimir Zapolskiy <vz@mleia.com> > --- > fs/sysfs/file.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/fs/sysfs/file.c b/fs/sysfs/file.c > index 7c2867b..6c95628 100644 > --- a/fs/sysfs/file.c > +++ b/fs/sysfs/file.c > @@ -90,7 +90,7 @@ static ssize_t sysfs_kf_bin_read(struct kernfs_open_file *of, char *buf, > return 0; > > if (size) { > - if (pos > size) > + if (pos >= size) > return 0; > if (pos + count > size) > count = size - pos;
Hmmm... maybe just move that test upwards?
if (!count || pos >= size) return 0;
count = min(count, size - pos);
-- tejun
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