Date: Fri, 30 Aug 2024 10:59:44 +1200
From: Tao Liu <ltao@redhat.com>
Subject: [Crash-utility] Re: [Crash-utility][PATCH] “kmem address” not
        working properly when redzone is enabled
To: "Aureau, Georges (Kernel Tools ERT)" <georges.aureau@hpe.com>
Cc: "devel@lists.crash-utility.osci.io"
        <devel@lists.crash-utility.osci.io>
Message-ID:
        <CAO7dBbV96Ys8sQ1u00b2x1L9SCyEuAGqKaN6Gb4UDX-XbnZXdQ@mail.gmail.com>
Content-Type: text/plain; charset="UTF-8"

Hi Georges

On Thu, Aug 29, 2024 at 9:55 PM Aureau, Georges (Kernel Tools ERT)
<georges.aureau@hpe.com> wrote:
>
> Crash “kmem address” not working properly when redzone is enabled.
>
> When "slub_debug" is enabled with redzoning, "kmem address" does not work properly.
> The "red_left_pad" member within "struct kmem_cache" is currently an "unsigned int",
> it used to be an "int", but it never was a "long", hence "red_left_pad" in do_slab_slub()
> was not initialized properly. This "red_left_pad" issue resulted in reporting free objects
> as "[ALLOCATED]", and in reporting bogus object addresses when using "set redzone off".
>
Thanks for the fix, LGTM, so ack.

Thanks,
Tao Liu

> Signed-off-by: Georges Aureau <georges.aureau@hpe.com>
> --
> diff --git a/memory.c b/memory.c
> index a74ebaf..967a9cf 100644
> --- a/memory.c
> +++ b/memory.c
> @@ -19637,7 +19637,8 @@ do_slab_slub(struct meminfo *si, int verbose)
>         int i, free_objects, cpu_slab, is_free, node;
>         ulong p, q;
>  #define SLAB_RED_ZONE 0x00000400UL
> -       ulong flags, red_left_pad;
> +       ulong flags;
> +       uint red_left_pad;
>
>         if (!si->slab) {
>                 if (CRASHDEBUG(1))
> @@ -19727,7 +19728,7 @@ do_slab_slub(struct meminfo *si, int verbose)
>         if (VALID_MEMBER(kmem_cache_red_left_pad)) {
>                 flags = ULONG(si->cache_buf + OFFSET(kmem_cache_flags));
>                 if (flags & SLAB_RED_ZONE)
> -                       red_left_pad = ULONG(si->cache_buf + OFFSET(kmem_cache_red_left_pad));
> +                       red_left_pad = UINT(si->cache_buf + OFFSET(kmem_cache_red_left_pad));
>         }
>
>         for (p = vaddr; p < vaddr + objects * si->size; p += si->size) {
> --