Messages in this thread | | | From | Jon Mason <> | Date | Tue, 5 Dec 2017 13:08:44 -0500 | Subject | Re: [PATCH v2 03/15] NTB: Fix UB/bug in ntb_mw_get_align() |
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On Tue, Dec 5, 2017 at 12:56 PM, Serge Semin <fancer.lancer@gmail.com> wrote: > On Tue, Dec 05, 2017 at 11:52:32AM -0500, Jon Mason <jdmason@kudzu.us> wrote: >> On Sun, Dec 3, 2017 at 2:17 PM, Serge Semin <fancer.lancer@gmail.com> wrote: >> > Simple (1 << pidx) operation causes undefined behaviour when >> > pidx >= 32. It must be casted to u64 to match the actual return >> > value of ntb_link_is_up() method, so to have all the possible >> > peer indexes covered and to get rid of undefined behaviour. >> > Additionally there are special macros in "linux/bitops.h" to perform >> > the bit-set-shift operations, so it's recommended to have them used >> > for proper bit setting. >> >> This looks good to me, but also seems like a bug fix. Please comment >> on if this is not noticed. >> > > The consequences of the bug isn't noticeable at the moment, but potentially > it can be seen on the devices like Switchtec (when multi-portness is finally > added). Anyway it's better to fix it now, than to wait for obvious bug. > Additionally as I said the originator of the code should have used BIT_ULL > instead of the pure bit shifting.
This is more of a question of whether it should go into -stable and be outside this patch set. If this is impossible to ever hit, then including it here instead of fast tracking it in -stable is fine.
Thanks, Jon
> > Thanks, > -Sergey > >> Thanks, >> Jon >> >> > >> > Signed-off-by: Serge Semin <fancer.lancer@gmail.com> >> > Reviewed-by: Logan Gunthorpe <logang@deltatee.com> >> > --- >> > include/linux/ntb.h | 2 +- >> > 1 file changed, 1 insertion(+), 1 deletion(-) >> > >> > diff --git a/include/linux/ntb.h b/include/linux/ntb.h >> > index c1646f2c6344..488e586fb76c 100644 >> > --- a/include/linux/ntb.h >> > +++ b/include/linux/ntb.h >> > @@ -764,7 +764,7 @@ static inline int ntb_mw_get_align(struct ntb_dev *ntb, int pidx, int widx, >> > resource_size_t *size_align, >> > resource_size_t *size_max) >> > { >> > - if (!(ntb_link_is_up(ntb, NULL, NULL) & (1 << pidx))) >> > + if (!(ntb_link_is_up(ntb, NULL, NULL) & BIT_ULL(pidx))) >> > return -ENOTCONN; >> > >> > return ntb->ops->mw_get_align(ntb, pidx, widx, addr_align, size_align, >> > -- >> > 2.12.0 >> >
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