[Crash-utility] Re: [PATCH] “kmem address” not working properly when redzone is enabled

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