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From: "Maciej Żenczykowski" <maze@google.com>
To: Maciej Wieczor-Retman <m.wieczorretman@pm.me>,
	Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Kees Cook <kees@kernel.org>,
	joonki.min@samsung-slsi.corp-partner.google.com,
	 Andrew Morton <akpm@google.com>,
	Alexander Potapenko <glider@google.com>,
	 Andrey Konovalov <andreyknvl@gmail.com>,
	Dmitry Vyukov <dvyukov@google.com>,
	 Vincenzo Frascino <vincenzo.frascino@arm.com>,
	Marco Elver <elver@google.com>,
	 Andrew Morton <akpm@linux-foundation.org>,
	Uladzislau Rezki <urezki@gmail.com>,
	 Danilo Krummrich <dakr@kernel.org>,
	jiayuan.chen@linux.dev,
	 syzbot+997752115a851cb0cf36@syzkaller.appspotmail.com,
	 Maciej Wieczor-Retman <maciej.wieczor-retman@intel.com>,
	kasan-dev@googlegroups.com,
	 Kernel hackers <linux-kernel@vger.kernel.org>,
	linux-mm@kvack.org
Subject: Re: KASAN vs realloc
Date: Fri, 6 Feb 2026 11:07:12 -0800	[thread overview]
Message-ID: <CANP3RGeHnhufYyc0P2OiKJbXdZjPW41TP=JS6nYk9xGRU8UuKQ@mail.gmail.com> (raw)
In-Reply-To: <CANP3RGeWLMQEMnC03pUr8=1+e27vma1ggiWGWcpX+PcZ=SsxUg@mail.gmail.com>

While looking at:
  https://android-review.git.corp.google.com/c/kernel/common/+/3939998
  UPSTREAM: mm/kasan: fix KASAN poisoning in vrealloc()

I noticed a lack of symmetry - I'm not sure if it's a problem or not...
but I'd have expected kasan_poison_last_granule() to be called
regardless of whether the size shrunk or increased.

It is of course possible this is handled automatically by
__kasan_unpoison_vmalloc() - I haven't traced that deep,
in general these functions seem to have a terrible api surface full of
razors... with hidden assumptions about what is and is not granule
aligned.


  reply	other threads:[~2026-02-06 19:07 UTC|newest]

Thread overview: 27+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-01-06 12:42 Maciej Żenczykowski
2026-01-07 20:28 ` Kees Cook
2026-01-07 20:47   ` Maciej Wieczor-Retman
2026-01-07 21:47     ` Maciej Żenczykowski
2026-01-07 21:50       ` Maciej Żenczykowski
2026-01-07 21:55         ` Maciej Żenczykowski
2026-01-09 18:55           ` Maciej Wieczor-Retman
2026-01-09 20:05             ` Maciej Żenczykowski
2026-02-06 19:07               ` Maciej Żenczykowski [this message]
2026-02-06 20:14                 ` Maciej Wieczor-Retman
2026-02-06 21:26                   ` Maciej Żenczykowski
2026-01-13 19:15 ` [PATCH 1/2] mm/kasan: Fix KASAN poisoning in vrealloc() Andrey Ryabinin
2026-01-13 19:15   ` [PATCH 2/2] mm/kasan/kunit: extend vmalloc OOB tests to cover vrealloc() Andrey Ryabinin
2026-01-15  3:56     ` Andrey Konovalov
2026-01-16 13:28       ` [PATCH] mm-kasan-kunit-extend-vmalloc-oob-tests-to-cover-vrealloc-fix Andrey Ryabinin
2026-01-16 18:53         ` Maciej Wieczor-Retman
2026-01-17  1:16         ` Andrey Konovalov
2026-01-14 12:17   ` [PATCH 1/2] mm/kasan: Fix KASAN poisoning in vrealloc() Maciej Wieczor-Retman
2026-01-15  3:56   ` Andrey Konovalov
2026-01-16 13:26     ` Andrey Ryabinin
2026-01-17  1:16       ` Andrey Konovalov
2026-01-17 17:08         ` Andrey Konovalov
2026-01-19  0:48           ` Andrew Morton
2026-01-19 14:43             ` Andrey Ryabinin
2026-01-19 14:45           ` [PATCH] mm-kasan-fix-kasan-poisoning-in-vrealloc-fix Andrey Ryabinin
2026-01-20 17:46             ` Andrey Konovalov
2026-01-21 16:01               ` Andrey Ryabinin

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