Messages in this thread | | | From | James Bottomley <> | Subject | Re: [PATCH] lib/string_helpers.c: fix infinite loop in string_get_size() | Date | Fri, 11 Sep 2015 01:22:43 +0000 |
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On Fri, 2015-09-04 at 14:56 +0200, Vitaly Kuznetsov 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. > > Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com> > --- > lib/string_helpers.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/lib/string_helpers.c b/lib/string_helpers.c > index c98ae81..a155c7b 100644 > --- a/lib/string_helpers.c > +++ b/lib/string_helpers.c > @@ -76,7 +76,7 @@ void string_get_size(u64 size, u64 blk_size, const enum string_size_units units, > i++; > } > > - sf_cap = size; > + sf_cap = size ? size : 1;
If size can become zero after the scale adjustment, then there's a fault in the algorithm, and this probably isn't the right fix. However, I did a brief calculation, and I can't see how size becomes zero ... it might be that I haven't looked at this long enough (I am on holiday).
James
> for (j = 0; sf_cap*10 < 1000; j++) > sf_cap *= 10; >
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