Date: Tue, 28 Nov 2023 18:23:35 +0100 From: Mateusz Guzik <mjguzik@gmail.com> To: Gleb Smirnoff <glebius@freebsd.org> Cc: src-committers@freebsd.org, dev-commits-src-all@freebsd.org, dev-commits-src-main@freebsd.org Subject: Re: git: e1e847374bcc - main - Add DEBUG_POISON_POINTER Message-ID: <CAGudoHGiE9_oDzWeGcpJ%2BE8SMewrd3Hay7sLkQFy%2BwpjioA4cA@mail.gmail.com> In-Reply-To: <ZWYhoEZSRqgvKKOF@FreeBSD.org> References: <202311281635.3ASGZeew027691@gitrepo.freebsd.org> <ZWYhoEZSRqgvKKOF@FreeBSD.org>
next in thread | previous in thread | raw e-mail | index | archive | help
On 11/28/23, Gleb Smirnoff <glebius@freebsd.org> wrote:
> Mateusz,
>
> On Tue, Nov 28, 2023 at 04:35:40PM +0000, Mateusz Guzik wrote:
> M> Add DEBUG_POISON_POINTER
> M>
> M> If you have a pointer which you know points to stale data, you can
> M> fill it with junk so that dereference later will trap
> M>
> M> Reviewed by: kib
> M> Sponsored by: Rubicon Communications, LLC ("Netgate")
> M> Differential Revision: https://reviews.freebsd.org/D40946
> M> ---
> M> sys/kern/vfs_bio.c | 6 ++++++
> M> sys/sys/kassert.h | 31 +++++++++++++++++++++++++++++++
> M> 2 files changed, 37 insertions(+)
> M>
> M> diff --git a/sys/kern/vfs_bio.c b/sys/kern/vfs_bio.c
> M> index 31059f1c0a94..4e0832475c3e 100644
> M> --- a/sys/kern/vfs_bio.c
> M> +++ b/sys/kern/vfs_bio.c
> M> @@ -159,6 +159,9 @@ nbufp(unsigned i)
> M> }
> M>
> M> caddr_t __read_mostly unmapped_buf;
> M> +#ifdef INVARIANTS
> M> +caddr_t poisoned_buf = (void *)-1;
> M> +#endif
>
> Is there any good reason to use caddr_t here instead of void *?
>
> Later it is casted back to normal void* in #define DEBUG_POISON_POINTER(x).
>
unmapped_buf is caddr. if you want to roll with void * feel free to change.
--
Mateusz Guzik <mjguzik gmail.com>
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?CAGudoHGiE9_oDzWeGcpJ%2BE8SMewrd3Hay7sLkQFy%2BwpjioA4cA>