Messages in this thread | | | From | Vitaly Kuznetsov <> | Subject | Re: [PATCH] lib/string_helpers.c: fix infinite loop in string_get_size() | Date | Mon, 14 Sep 2015 14:43:30 +0200 |
| |
Andy Shevchenko <andriy.shevchenko@linux.intel.com> writes:
> On Fri, 2015-09-11 at 18:31 +0000, James Bottomley wrote: >> On Thu, 2015-09-10 at 16:08 -0700, Andrew Morton wrote: >> > On Fri, 4 Sep 2015 14:56:33 +0200 Vitaly Kuznetsov < >> > vkuznets@redhat.com> wrote: >> > >> > > string_get_size(1, 512, 0, ..., ...) call results in an infinite >> > > loop. The >> > > problem is that if size == 0 when we start calculating sf_cap >> > > this loop >> > > will never end. >> > > >> > > The caller causing the issue is sd_read_capacity(), the problem >> > > was noticed >> > > on Hyper-V. >> > >> > When fixing bugs, please provide enough info for others to be able >> > to >> > understand which kernel version(s) need the fix. In this case: >> > what >> > end-user action triggers this bug? (iow, how does sdkp->capacity >> > become zero?) >> >> Any more details. The attached programme, which is cut straight out >> of >> the algorithm in string_helpers.c and modified for a C environment >> slightly (only in do_div and the typedefs) produces this >> >> hello >> STRING IS 512 B >> >> With your input, so I don't think the problem is where you think it >> is. >> >> James >> > > Vitaly, it might make sense to extend test-string_helpers.c to what you > are trying to do right.
The issue is that string_get_size() enters an infinite loop on some inputs so if we add a test for such inputs we'll hang our kernel...
-- Vitaly
| |