linux-kernel - Re: [PATCH v2 00/11] kasan: unify kasan_arch_is_ready with kasan

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <CACzwLxgsVkn98VDPpmm7pKcbvu87UBwPgYJmLfKixu4-x+yjSA@mail.gmail.com>
Date: Sat, 28 Jun 2025 18:25:17 +0500
From: Sabyrzhan Tasbolatov <snovitoll@...il.com>
To: Andrey Konovalov <andreyknvl@...il.com>
Cc: ryabinin.a.a@...il.com, glider@...gle.com, dvyukov@...gle.com, 
	vincenzo.frascino@....com, linux@...linux.org.uk, catalin.marinas@....com, 
	will@...nel.org, chenhuacai@...nel.org, kernel@...0n.name, 
	maddy@...ux.ibm.com, mpe@...erman.id.au, npiggin@...il.com, 
	christophe.leroy@...roup.eu, paul.walmsley@...ive.com, palmer@...belt.com, 
	aou@...s.berkeley.edu, alex@...ti.fr, hca@...ux.ibm.com, gor@...ux.ibm.com, 
	agordeev@...ux.ibm.com, borntraeger@...ux.ibm.com, svens@...ux.ibm.com, 
	richard@....at, anton.ivanov@...bridgegreys.com, johannes@...solutions.net, 
	dave.hansen@...ux.intel.com, luto@...nel.org, peterz@...radead.org, 
	tglx@...utronix.de, mingo@...hat.com, bp@...en8.de, x86@...nel.org, 
	hpa@...or.com, chris@...kel.net, jcmvbkbc@...il.com, 
	akpm@...ux-foundation.org, nathan@...nel.org, nick.desaulniers+lkml@...il.com, 
	morbo@...gle.com, justinstitt@...gle.com, arnd@...db.de, rppt@...nel.org, 
	geert@...ux-m68k.org, mcgrof@...nel.org, guoweikang.kernel@...il.com, 
	tiwei.btw@...group.com, kevin.brodsky@....com, benjamin.berg@...el.com, 
	kasan-dev@...glegroups.com, linux-arm-kernel@...ts.infradead.org, 
	linux-kernel@...r.kernel.org, loongarch@...ts.linux.dev, 
	linuxppc-dev@...ts.ozlabs.org, linux-riscv@...ts.infradead.org, 
	linux-s390@...r.kernel.org, linux-um@...ts.infradead.org, linux-mm@...ck.org, 
	llvm@...ts.linux.dev
Subject: Re: [PATCH v2 00/11] kasan: unify kasan_arch_is_ready with kasan_enabled

On Sat, Jun 28, 2025 at 3:57 PM Andrey Konovalov <andreyknvl@...il.com> wrote:
>
> On Thu, Jun 26, 2025 at 5:32 PM Sabyrzhan Tasbolatov
> <snovitoll@...il.com> wrote:
> >
> > This patch series unifies the kasan_arch_is_ready() and kasan_enabled()
> > interfaces by extending the existing kasan_enabled() infrastructure to
> > work consistently across all KASAN modes (Generic, SW_TAGS, HW_TAGS).
> >
> > Currently, kasan_enabled() only works for HW_TAGS mode using a static key,
> > while other modes either return IS_ENABLED(CONFIG_KASAN) (compile-time
> > constant) or rely on architecture-specific kasan_arch_is_ready()
> > implementations with custom static keys and global variables.
> >
> > This leads to:
> > - Code duplication across architectures
> > - Inconsistent runtime behavior between KASAN modes
> > - Architecture-specific readiness tracking
> >
> > After this series:
> > - All KASAN modes use the same kasan_flag_enabled static key
> > - Consistent runtime enable/disable behavior across modes
> > - Simplified architecture code with unified kasan_init_generic() calls
> > - Elimination of arch specific kasan_arch_is_ready() implementations
> > - Unified vmalloc integration using kasan_enabled() checks
> >
> > This addresses the bugzilla issue [1] about making
> > kasan_flag_enabled and kasan_enabled() work for Generic mode,
> > and extends it to provide true unification across all modes.
> >
> > [1] https://bugzilla.kernel.org/show_bug.cgi?id=217049
>
> Hi Sabyrzhan,
>
> Thank you for working on this!
>
> One aspect that is missing from the patches is moving the
> kasan_arch_is_ready() calls into the include/linux/kasan.h (this is
> not explicitly mentioned in the issue, but this is what the "adding
> __wrappers" part is about).
>
> Another thing that needs careful consideration is whether it's
> possible to combine kasan_arch_is_ready() and kasan_enabled() into the
> same check logically at all. There's one issue mentioned in [1]:

Hello,
I've removed kasan_arch_is_ready() at all in this series:
[PATCH v2 11/11] kasan: replace kasan_arch_is_ready with kasan_enabled

Is it not what's expected by unification?

>
> > In kasan_cache_create() we unconditionally allocate a metadata buffer,
> > but the kasan_init_slab_obj() call to initialise it is guarded by
> > kasan_enabled(). But later parts of the code only check the presence of
> > the buffer before using it, so bad things happen if kasan_enabled()
> > later turns on (I was getting some error about invalid lock state).
>
> And there might be other callbacks that should be executed even before
> kasan_init_...() completes. But then for the HW_TAGS mode, if
> kasan_enabled() is off, then we don't want to execute any callbacks.
>
> So maybe we do actually need a separate static key for
> kasan_arch_is_ready(). But even if so, it still makes sense to move
> kasan_arch_is_ready() into the __wrappers for the affected callbacks.
>
> Thanks!
>
> [1] https://lore.kernel.org/linux-mm/CA+fCnZf7JqTH46C7oG2Wk9NnLU7hgiVDEK0EA8RAtyr-KgkHdg@mail.gmail.com/