On Mon 2019-05-20 09:26:45, Gustavo A. R. Silva wrote: > > > On 5/20/19 9:00 AM, Greg KH wrote: > > On Mon, May 20, 2019 at 02:40:14PM +0200, Pavel Machek wrote: > >> > >> In lecd_attach, if arg is < 0, it was treated as 0. Spectre v1 fix > >> changed that. Bug does not exist in mainline AFAICT. > >> > >> Signed-off-by: Pavel Machek <[email protected]> > >> # for 4.19.y > >> > >> diff --git a/net/atm/lec.c b/net/atm/lec.c > >> index ad4f829193f0..ed279cd912f4 100644 > >> --- a/net/atm/lec.c > >> +++ b/net/atm/lec.c > >> @@ -731,7 +731,7 @@ static int lecd_attach(struct atm_vcc *vcc, int arg) > >> i = arg; > >> if (arg >= MAX_LEC_ITF) > >> return -EINVAL; > >> - i = array_index_nospec(arg, MAX_LEC_ITF); > >> + i = array_index_nospec(i, MAX_LEC_ITF); > >> if (!dev_lec[i]) { > >> int size; > >> > > > > Why is this only for 4.19.y? What is different in Linus's tree that > > makes this not needed there? > > > > The only difference is this clean up: > > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=fdd1a8103a6df50bdeacd8bb04c3f6976cb9ae41 > > As Dan says, the code works fine, but the *i* value wasn't being used > anymore, so that piece of code was a bit confusing.
Yep, you are right, code managed to confused me: array_index_nospec
really returns 0 if it is out of bounds,
(typeof(_i)) (_i & _mask);
because _mask is always 0 or ~0.
Best regards,
Pavel
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