Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > linux.kernel > #1222429 > unrolled thread

Re: [PATCH] lib/string_helpers.c: fix infinite loop in string_get_size()

Back to article view | Back to linux.kernel

This discussion starts older than the indexed window; earlier articles aren't shown. The article labeled Started by below is the oldest one visible, not the original post.

Contents

  Re: [PATCH] lib/string_helpers.c: fix infinite loop in  string_get_size() Andrew Morton <akpm@linux-foundation.org> - 2015-09-11 01:10 +0200
    Re: [PATCH] lib/string_helpers.c: fix infinite loop in  string_get_size() James Bottomley <jbottomley@odin.com> - 2015-09-11 20:40 +0200
      Re: [PATCH] lib/string_helpers.c: fix infinite loop in  string_get_size() Andy Shevchenko <andriy.shevchenko@linux.intel.com> - 2015-09-14 11:10 +0200
        Re: [PATCH] lib/string_helpers.c: fix infinite loop in string_get_size() Vitaly Kuznetsov <vkuznets@redhat.com> - 2015-09-14 14:50 +0200
          Re: [PATCH] lib/string_helpers.c: fix infinite loop in  string_get_size() Andy Shevchenko <andriy.shevchenko@linux.intel.com> - 2015-09-14 16:40 +0200
      Re: [PATCH] lib/string_helpers.c: fix infinite loop in string_get_size() Vitaly Kuznetsov <vkuznets@redhat.com> - 2015-09-14 11:20 +0200

#1222429 — Re: [PATCH] lib/string_helpers.c: fix infinite loop in string_get_size()

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?)




--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/

[toc] | [next] | [standalone]

#1223033

[Multipart message — attachments visible in raw view] — view raw

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

[toc] | [prev] | [next] | [standalone]

#1223956

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.


-- 
Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Intel Finland Oy
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/

[toc] | [prev] | [next] | [standalone]

#1224107 — Re: [PATCH] lib/string_helpers.c: fix infinite loop in string_get_size()

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
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/

[toc] | [prev] | [next] | [standalone]

#1224206

On Mon, 2015-09-14 at 14:43 +0200, Vitaly Kuznetsov wrote:
> 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...
> 

I didn't see a problem to add this test case. Since test module is
dedicated for that (tests).

-- 
Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Intel Finland Oy
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/

[toc] | [prev] | [next] | [standalone]

#1223965 — Re: [PATCH] lib/string_helpers.c: fix infinite loop in string_get_size()

James Bottomley <jbottomley@odin.com> writes:

> 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.

Sorry for delayed reply, I was traveling.

Please change
string_get_size(1, 512, STRING_UNITS_2, buf, sizeof(buf));

to
string_get_size(1, 512, STRING_UNITS_10, buf, sizeof(buf));

in your test.c program to see the issue, it will enter the infinite loop
as well.

Regardless to Hyper-V I think such library function shouldn't do such
nasty things (but I'll try to investigate why such small size was
reported).

-- 
  Vitaly
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/

[toc] | [prev] | [standalone]

Back to top | Article view | linux.kernel

csiph-web