On 05/09/2014 12:03 PM, H. Peter Anvin wrote:
On 05/09/2014 08:59 AM, Boris Ostrovsky wrote:
On 05/09/2014 11:43 AM, H. Peter Anvin wrote:
On 05/09/2014 08:11 AM, Boris Ostrovsky wrote:
With tk->wall_to_monotonic.tv_nsec being a 32-bit value on 32-bit
systems, (tk->wall_to_monotonic.tv_nsec << tk->shift) in
update_vsyscall()
may lose upper bits or, worse, add them since compiler will do this:
(u64)(tk->wall_to_monotonic.tv_nsec << tk->shift)
instead of
((u64)tk->wall_to_monotonic.tv_nsec << tk->shift)
So if, for example, tv_nsec is 0x800000 and shift is 8 we will end up
with 0xffffffff80000000 instead of 0x80000000. And then we are stuck in
the subsequent 'while' loop.
We need explicit cast.
Signed-off-by: Boris Ostrovsky <[email protected]>
Acked-by: Konrad Rzeszutek Wilk <[email protected]>
Cc: [email protected]
This is needed in stable only for v3.14, right?
I suspect anything that has commit 650ea024 needs to be fixed. I see
this code, for example, in 3.12 (it used to be in vsyscall_64.c).
But you're talking about 32-bit platforms. Vsyscalls aren't used on
x86-32 until 3.14. Am I missing something?
Oh, yes, of course. I was just looking at code without thinking. 3.14
only then.
-boris
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