* Re: Fw: [PATCH] lib/kstrtox.c Stop parsing integer on overflow [not found] <20150217161724.65a9ff577f84917497d61b4e@linux-foundation.org> @ 2015-02-18 7:44 ` Alexey Dobriyan 2015-02-19 17:53 ` Anshul Garg 0 siblings, 1 reply; 3+ messages in thread From: Alexey Dobriyan @ 2015-02-18 7:44 UTC (permalink / raw) To: Andrew Morton; +Cc: aksgarg1989, linux-kernel On Tue, Feb 17, 2015 at 04:17:24PM -0800, Andrew Morton wrote: > ? > > Begin forwarded message: > > Date: Mon, 16 Feb 2015 10:48:50 -0800 > From: Anshul Garg <aksgarg1989@gmail.com> > To: linux-kernel@vger.kernel.org > Cc: aksgarg1989@gmail.com, anshul.g@samsung.com, torvalds@linux-foundation.org > Subject: [PATCH] lib/kstrtox.c Stop parsing integer on overflow > > > From: Anshul Garg <aksgarg1989@gmail.com> > > While converting string representation to integer > break the loop if overflow is detected. > > Signed-off-by: Anshul Garg <aksgarg1989@gmail.com> > --- > lib/kstrtox.c | 4 +++- > 1 file changed, 3 insertions(+), 1 deletion(-) > > diff --git a/lib/kstrtox.c b/lib/kstrtox.c > index ec8da78..6f30209 100644 > --- a/lib/kstrtox.c > +++ b/lib/kstrtox.c > @@ -70,8 +70,10 @@ unsigned int _parse_integer(const char *s, unsigned int base, unsigned long long > * it in the max base we support (16) > */ > if (unlikely(res & (~0ull << 60))) { > - if (res > div_u64(ULLONG_MAX - val, base)) > + if (res > div_u64(ULLONG_MAX - val, base)) { > overflow = 1; > + break; > + } > } > res = res * base + val; > rv++; The _notion_ of a patch is OK if you want EVERY simple_strtoull() call to stop parsing past overflow right now. It SHOULD have done so from day 1, but it doesn't do that. When I wrote kstrto*() code I deliberatedly didn't break this bug because of the sheer number of call sites. If you are OK with changing bug-for-bug compatibility, then patch simply need to delete overflow detection code. Alexey ^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: Fw: [PATCH] lib/kstrtox.c Stop parsing integer on overflow 2015-02-18 7:44 ` Fw: [PATCH] lib/kstrtox.c Stop parsing integer on overflow Alexey Dobriyan @ 2015-02-19 17:53 ` Anshul Garg 2015-02-20 11:08 ` Alexey Dobriyan 0 siblings, 1 reply; 3+ messages in thread From: Anshul Garg @ 2015-02-19 17:53 UTC (permalink / raw) To: Alexey Dobriyan; +Cc: Andrew Morton, Linux Kernel Mailing List On Wed, Feb 18, 2015 at 1:14 PM, Alexey Dobriyan <adobriyan@gmail.com> wrote: > On Tue, Feb 17, 2015 at 04:17:24PM -0800, Andrew Morton wrote: >> ? >> >> Begin forwarded message: >> >> Date: Mon, 16 Feb 2015 10:48:50 -0800 >> From: Anshul Garg <aksgarg1989@gmail.com> >> To: linux-kernel@vger.kernel.org >> Cc: aksgarg1989@gmail.com, anshul.g@samsung.com, torvalds@linux-foundation.org >> Subject: [PATCH] lib/kstrtox.c Stop parsing integer on overflow >> >> >> From: Anshul Garg <aksgarg1989@gmail.com> >> >> While converting string representation to integer >> break the loop if overflow is detected. >> >> Signed-off-by: Anshul Garg <aksgarg1989@gmail.com> >> --- >> lib/kstrtox.c | 4 +++- >> 1 file changed, 3 insertions(+), 1 deletion(-) >> >> diff --git a/lib/kstrtox.c b/lib/kstrtox.c >> index ec8da78..6f30209 100644 >> --- a/lib/kstrtox.c >> +++ b/lib/kstrtox.c >> @@ -70,8 +70,10 @@ unsigned int _parse_integer(const char *s, unsigned int base, unsigned long long >> * it in the max base we support (16) >> */ >> if (unlikely(res & (~0ull << 60))) { >> - if (res > div_u64(ULLONG_MAX - val, base)) >> + if (res > div_u64(ULLONG_MAX - val, base)) { >> overflow = 1; >> + break; >> + } >> } >> res = res * base + val; >> rv++; > > The _notion_ of a patch is OK if you want EVERY simple_strtoull() call > to stop parsing past overflow right now. It SHOULD have done so from day 1, > but it doesn't do that. > > When I wrote kstrto*() code I deliberatedly didn't break this bug > because of the sheer number of call sites. > > If you are OK with changing bug-for-bug compatibility, > then patch simply need to delete overflow detection code. > > Alexey I think this patch won't break any existing module using this function. because this function sets KSTRTOX_OVERFLOW as error status. which is checked by calling function to determine whether value is correct or not. If this flag is set we can simply discard the parsed value. ^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: Fw: [PATCH] lib/kstrtox.c Stop parsing integer on overflow 2015-02-19 17:53 ` Anshul Garg @ 2015-02-20 11:08 ` Alexey Dobriyan 0 siblings, 0 replies; 3+ messages in thread From: Alexey Dobriyan @ 2015-02-20 11:08 UTC (permalink / raw) To: Anshul Garg; +Cc: Andrew Morton, Linux Kernel Mailing List On Thu, Feb 19, 2015 at 8:53 PM, Anshul Garg <aksgarg1989@gmail.com> wrote: > On Wed, Feb 18, 2015 at 1:14 PM, Alexey Dobriyan <adobriyan@gmail.com> wrote: >> On Tue, Feb 17, 2015 at 04:17:24PM -0800, Andrew Morton wrote: >>> ? >>> >>> Begin forwarded message: >>> >>> Date: Mon, 16 Feb 2015 10:48:50 -0800 >>> From: Anshul Garg <aksgarg1989@gmail.com> >>> To: linux-kernel@vger.kernel.org >>> Cc: aksgarg1989@gmail.com, anshul.g@samsung.com, torvalds@linux-foundation.org >>> Subject: [PATCH] lib/kstrtox.c Stop parsing integer on overflow >>> >>> >>> From: Anshul Garg <aksgarg1989@gmail.com> >>> >>> While converting string representation to integer >>> break the loop if overflow is detected. >>> >>> Signed-off-by: Anshul Garg <aksgarg1989@gmail.com> >>> --- >>> lib/kstrtox.c | 4 +++- >>> 1 file changed, 3 insertions(+), 1 deletion(-) >>> >>> diff --git a/lib/kstrtox.c b/lib/kstrtox.c >>> index ec8da78..6f30209 100644 >>> --- a/lib/kstrtox.c >>> +++ b/lib/kstrtox.c >>> @@ -70,8 +70,10 @@ unsigned int _parse_integer(const char *s, unsigned int base, unsigned long long >>> * it in the max base we support (16) >>> */ >>> if (unlikely(res & (~0ull << 60))) { >>> - if (res > div_u64(ULLONG_MAX - val, base)) >>> + if (res > div_u64(ULLONG_MAX - val, base)) { >>> overflow = 1; >>> + break; >>> + } >>> } >>> res = res * base + val; >>> rv++; >> >> The _notion_ of a patch is OK if you want EVERY simple_strtoull() call >> to stop parsing past overflow right now. It SHOULD have done so from day 1, >> but it doesn't do that. >> >> When I wrote kstrto*() code I deliberatedly didn't break this bug >> because of the sheer number of call sites. >> >> If you are OK with changing bug-for-bug compatibility, >> then patch simply need to delete overflow detection code. >> >> Alexey > > I think this patch won't break any existing module using this function. > because this function sets KSTRTOX_OVERFLOW as error status. > > which is checked by calling function to determine whether value is correct > or not. > > If this flag is set we can simply discard the parsed value. Which is my previous email is all about. If you discard, every single simple_strto*() call will change its behaviour. If you're OK with that, patch is incomplete. Alexey ^ permalink raw reply [flat|nested] 3+ messages in thread
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2015-02-18 7:44 ` Fw: [PATCH] lib/kstrtox.c Stop parsing integer on overflow Alexey Dobriyan
2015-02-19 17:53 ` Anshul Garg
2015-02-20 11:08 ` Alexey Dobriyan
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