Messages in this thread | | | Date | Thu, 30 Oct 2008 02:28:16 +1300 | From | "Phillip O'Donnell" <> | Subject | Re: [PATCH] libata: Avoid overflow in ata_tf_to_lba48() when tf->hba_lbal > 127 |
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Confirmed - HPA is no longer detected on boot.
Cheers, Phillip
On Wed, Oct 29, 2008 at 12:52 PM, Roland Dreier <rdreier@cisco.com> wrote: > In ata_tf_to_lba48(), when evaluating > > (tf->hob_lbal & 0xff) << 24 > > the expression is promoted to signed int (since int can hold all values > of u8). However, if hob_lbal is 128 or more, then it is treated as a > negative signed value and sign-extended when promoted to u64 to | into > sectors, which leads to the MSB 32 bits of section getting set > incorrectly. > > For example, Phillip O'Donnell <phillip.odonnell@gmail.com> reported > that a 1.5GB drive caused: > > ata3.00: HPA detected: current 2930277168, native 18446744072344861488 > > where 2930277168 == 0xAEA87B30 and 18446744072344861488 == 0xffffffffaea87b30 > which shows the problem when hob_lbal is 0xae. > > Fix this by adding a cast to u64, just as is used by for hob_lbah and > hob_lbam in the function. > > Reported-by: Phillip O'Donnell <phillip.odonnell@gmail.com> > Signed-off-by: Roland Dreier <rolandd@cisco.com> > --- > Phillip, this should fix at least your cosmetic issue; can you test it > and report back? > > Thanks, > Roland > > drivers/ata/libata-core.c | 2 +- > 1 files changed, 1 insertions(+), 1 deletions(-) > > diff --git a/drivers/ata/libata-core.c b/drivers/ata/libata-core.c > index bbb3cae..10424ff 100644 > --- a/drivers/ata/libata-core.c > +++ b/drivers/ata/libata-core.c > @@ -1268,7 +1268,7 @@ u64 ata_tf_to_lba48(const struct ata_taskfile *tf) > > sectors |= ((u64)(tf->hob_lbah & 0xff)) << 40; > sectors |= ((u64)(tf->hob_lbam & 0xff)) << 32; > - sectors |= (tf->hob_lbal & 0xff) << 24; > + sectors |= ((u64)(tf->hob_lbal & 0xff)) << 24; > sectors |= (tf->lbah & 0xff) << 16; > sectors |= (tf->lbam & 0xff) << 8; > sectors |= (tf->lbal & 0xff); >
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