Messages in this thread | | | Subject | Re: [PATCH] PNP: fix unintended sign extension on left shifts | From | "Rafael J. Wysocki" <> | Date | Tue, 15 Oct 2019 18:29:32 +0200 |
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On 10/14/2019 3:16 PM, Colin King wrote: > From: Colin Ian King <colin.king@canonical.com> > > Shifting a u8 left will cause the value to be promoted to an integer. If > the top bit of the u8 is set then the following conversion to a 64 bit > resource_size_t will sign extend the value causing the upper 32 bits > to be set in the result. > > Fix this by casting the u8 value to a resource_size_t before the shift. > Original commit is pre-git history. > > Signed-off-by: Colin Ian King <colin.king@canonical.com>
Please resend this with a Cc to linux-acpi@vger.kernel.org for easier handling.
> --- > drivers/pnp/isapnp/core.c | 18 ++++++++++++------ > 1 file changed, 12 insertions(+), 6 deletions(-) > > diff --git a/drivers/pnp/isapnp/core.c b/drivers/pnp/isapnp/core.c > index 179b737280e1..c947b1673041 100644 > --- a/drivers/pnp/isapnp/core.c > +++ b/drivers/pnp/isapnp/core.c > @@ -511,10 +511,14 @@ static void __init isapnp_parse_mem32_resource(struct pnp_dev *dev, > unsigned char flags; > > isapnp_peek(tmp, size); > - min = (tmp[4] << 24) | (tmp[3] << 16) | (tmp[2] << 8) | tmp[1]; > - max = (tmp[8] << 24) | (tmp[7] << 16) | (tmp[6] << 8) | tmp[5]; > - align = (tmp[12] << 24) | (tmp[11] << 16) | (tmp[10] << 8) | tmp[9]; > - len = (tmp[16] << 24) | (tmp[15] << 16) | (tmp[14] << 8) | tmp[13]; > + min = ((resource_size_t)tmp[4] << 24) | (tmp[3] << 16) | > + (tmp[2] << 8) | tmp[1]; > + max = ((resource_size_t)tmp[8] << 24) | (tmp[7] << 16) | > + (tmp[6] << 8) | tmp[5]; > + align = ((resource_size_t)tmp[12] << 24) | (tmp[11] << 16) | > + (tmp[10] << 8) | tmp[9]; > + len = ((resource_size_t)tmp[16] << 24) | (tmp[15] << 16) | > + (tmp[14] << 8) | tmp[13]; > flags = tmp[0]; > pnp_register_mem_resource(dev, option_flags, > min, max, align, len, flags); > @@ -532,8 +536,10 @@ static void __init isapnp_parse_fixed_mem32_resource(struct pnp_dev *dev, > unsigned char flags; > > isapnp_peek(tmp, size); > - base = (tmp[4] << 24) | (tmp[3] << 16) | (tmp[2] << 8) | tmp[1]; > - len = (tmp[8] << 24) | (tmp[7] << 16) | (tmp[6] << 8) | tmp[5]; > + base = ((resource_size_t)tmp[4] << 24) | (tmp[3] << 16) | > + (tmp[2] << 8) | tmp[1]; > + len = ((resource_size_t)tmp[8] << 24) | (tmp[7] << 16) | > + (tmp[6] << 8) | tmp[5]; > flags = tmp[0]; > pnp_register_mem_resource(dev, option_flags, base, base, 0, len, flags); > }
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