On Sat, Jul 16, 2022 at 08:43:06PM +0200, Geert Uytterhoeven wrote:

On Sat, Jul 16, 2022 at 1:33 AM Andrew Morton [off-list ref] wrote:

quoted

On Fri, 15 Jul 2022 10:17:43 +0200 Geert Uytterhoeven [off-list ref] wrote:

quoted

On Tue, Jun 28, 2022 at 1:42 PM [off-list ref] wrote:

quoted

From: Yee Lee <redacted>

This patch solves two issues.

(1) The pool allocated by memblock needs to unregister from
kmemleak scanning. Apply kmemleak_ignore_phys to replace the
original kmemleak_free as its address now is stored in the phys tree.

(2) The pool late allocated by page-alloc doesn't need to unregister.
Move out the freeing operation from its call path.

Suggested-by: Catalin Marinas <catalin.marinas@arm.com>
Suggested-by: Marco Elver <elver@google.com>
Signed-off-by: Yee Lee <redacted>

Thank you, this fixes the storm of

    BUG: KFENCE: invalid read in scan_block+0x78/0x130
    BUG: KFENCE: use-after-free read in scan_block+0x78/0x130
    BUG: KFENCE: out-of-bounds read in scan_block+0x78/0x130

messages I was seeing on arm64.

Thanks, but...

- It would be great if we could identify a Fixes: for this.

IIRC, I started seeing the issue with "[PATCH v4 3/4] mm:
kmemleak: add rbtree and store physical address for objects
allocated with PA" (i.e. commit 0c24e061196c21d5 ("mm: kmemleak:
add rbtree and store physical address for objects allocated
with PA")) of series "[PATCH v4 0/4] mm: kmemleak: store objects
allocated with physical address separately and check when scan"
(https://lore.kernel.org/all/20220611035551.1823303-1-patrick.wang.shcn@gmail.com (local)),
in an arm64 config that had enabled kfence.

Yes, I think it fixes 0c24e061196c21d5 since after that commit, the
kmemleak_free() no longer worked as expected on physically allocated
objects.

-- 
Catalin

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