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Re: Reading uninitialized memory
From: |
Torbjorn Granlund |
Subject: |
Re: Reading uninitialized memory |
Date: |
25 Jan 2002 18:31:44 +0100 |
User-agent: |
Gnus/5.0807 (Gnus v5.8.7) Emacs/20.7 |
Andrew Vaught <address@hidden> writes:
On 25 Jan 2002, Torbjorn Granlund wrote:
> Andrew Vaught <address@hidden> writes:
>
> I'm guessing that zero is stored without limbs and that
> mpz_get_si() always reads whatever passes for a non-limb. The value
> read from uninitialized memory is not used and doesn't affect the
> value of zero, but you could get rid of a read and the spurious
> error message from this and other bounds-checking programs.
>
> Your analysis is correct.
Here is a simple patch to avoid the problem:
I remain to be convinced that this problem should be patched in GMP.
It is an optimization to read memory speculatively, if we know it is
from a valid address. It would be better to fix the checker program
to track undefined values and make sure they aren't actually used, or
else live with their inaccuracies.
--
Torbjörn
- Reading uninitialized memory, Andrew Vaught, 2002/01/25
- Re: Reading uninitialized memory, Torbjorn Granlund, 2002/01/25
- Re: Reading uninitialized memory, Andrew Vaught, 2002/01/25
- Re: Reading uninitialized memory,
Torbjorn Granlund <=
- Re: Reading uninitialized memory, Kevin Ryde, 2002/01/25
- Re: Reading uninitialized memory, Andrew Vaught, 2002/01/26
- Re: Reading uninitialized memory, Kevin Ryde, 2002/01/26
- Re: Reading uninitialized memory, Andrew Vaught, 2002/01/26
- Re: Reading uninitialized memory, Torbjorn Granlund, 2002/01/26
- Re: Reading uninitialized memory, Kevin Ryde, 2002/01/26
- Re: Reading uninitialized memory, Andrew Vaught, 2002/01/26
- Re: Reading uninitialized memory, Torbjorn Granlund, 2002/01/26
- Re: Reading uninitialized memory, Andrew Vaught, 2002/01/26