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a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1757617463; bh=rAkxJv/3foIdEfVT/80z5+2GaTUuEqXXoELt3KTULG8=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=NgJmdhFvffaNkMSKeLoRpu+BnvJeOxJacaNKJSvtWNB1ifuG1HbrVSUULpPk+HQTF okO7XR2T2wbnFk5b984nMc3a+aawQ7vgfYEdNW9JXoRJsq1CSz9U4Nu5zaLWmLy1RA YwQldVWYU9cZZpA9+abgE4xT0KNL/Tuvr4RMb/CQoN8XNEl3mBRPj6/z3lNeH+lJqR GO5W3DaTKfRg0oXV4gSl8J4aZN/GKze3RboCNWE+38ZCoQE16qhsbxhCVYZqfBuub5 GlVDqhyoovt7YtbvdcWqnkTAFI9ruXz7XSXrymPM0p/SIwPWNBRdcPJjKqUuGvJzt8 OxbFMrs3ZEXwA== Date: Thu, 11 Sep 2025 12:03:02 -0700 From: Eric Biggers To: Alexander Potapenko Cc: Marco Elver , kasan-dev@googlegroups.com, Dmitry Vyukov , linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-crypto@vger.kernel.org, stable@vger.kernel.org, Vlastimil Babka Subject: Re: [PATCH] kmsan: Fix out-of-bounds access to shadow memory Message-ID: <20250911190302.GF1376@sol> References: <20250829164500.324329-1-ebiggers@kernel.org> <20250910194921.GA3153735@google.com> <20250911175145.GA1376@sol> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20250911175145.GA1376@sol> X-Rspamd-Server: rspam11 X-Rspamd-Queue-Id: 2BCACA0016 X-Stat-Signature: 9gyjn1mtzyo4a3ek48ag4o3k6gcjz7uf X-Rspam-User: X-HE-Tag: 1757617464-427487 X-HE-Meta: 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 ianjpm4x GB7zM6seYGJE2IuxBmXb33fcxGVQgKRBaPicyeHWxvxDiwSyl3jfAJ/Nq/B9pu8Vlw1WRUAQvs+x7QstX+vui70Vc3RYMpCvqptebb6WHIJVgmWPpyP4yAzPoly6P0PnosJhqwXI0ua8018P1Su2RIthiWGtZdvbumJw3VYicpt68DnDDYZRahRyMwS1IIjnhHOeBcXcDS+L5YWHRZC5hF16QgTpfIunEHkzysuWaFv0t9unAgD14iyrdhxFfv5V+o718nkqhg+XC2VPmglMwAcBoHnCA0/kwF/qBUJ7uCukyL7SwAZaCY3L/PDcZIoyVXZr4YowLirQNlBJULBkdzEpfGd/gIno6Ep+N8Qd50Z74gPE= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Thu, Sep 11, 2025 at 10:51:45AM -0700, Eric Biggers wrote: > On Thu, Sep 11, 2025 at 11:09:17AM +0200, Alexander Potapenko wrote: > > On Wed, Sep 10, 2025 at 9:49 PM Eric Biggers wrote: > > > > > > On Fri, Aug 29, 2025 at 09:45:00AM -0700, Eric Biggers wrote: > > > > Running sha224_kunit on a KMSAN-enabled kernel results in a crash in > > > > kmsan_internal_set_shadow_origin(): > > > > > > > > BUG: unable to handle page fault for address: ffffbc3840291000 > > > > #PF: supervisor read access in kernel mode > > > > #PF: error_code(0x0000) - not-present page > > > > PGD 1810067 P4D 1810067 PUD 192d067 PMD 3c17067 PTE 0 > > > > Oops: 0000 [#1] SMP NOPTI > > > > CPU: 0 UID: 0 PID: 81 Comm: kunit_try_catch Tainted: G N 6.17.0-rc3 #10 PREEMPT(voluntary) > > > > Tainted: [N]=TEST > > > > Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.17.0-0-gb52ca86e094d-prebuilt.qemu.org 04/01/2014 > > > > RIP: 0010:kmsan_internal_set_shadow_origin+0x91/0x100 > > > > [...] > > > > Call Trace: > > > > > > > > __msan_memset+0xee/0x1a0 > > > > sha224_final+0x9e/0x350 > > > > test_hash_buffer_overruns+0x46f/0x5f0 > > > > ? kmsan_get_shadow_origin_ptr+0x46/0xa0 > > > > ? __pfx_test_hash_buffer_overruns+0x10/0x10 > > > > kunit_try_run_case+0x198/0xa00 > > > > > > Any thoughts on this patch from the KMSAN folks? I'd love to add > > > CONFIG_KMSAN=y to my crypto subsystem testing, but unfortunately the > > > kernel crashes due to this bug :-( > > > > > > - Eric > > > > Sorry, I was out in August and missed this email when digging through my inbox. > > > > Curiously, I couldn't find any relevant crashes on the KMSAN syzbot > > instance, but the issue is legit. > > Thank you so much for fixing this! > > > > Any chance you can add a test case for it to mm/kmsan/kmsan_test.c? > > Unfortunately most of the KMSAN test cases already fail on upstream, > which makes it difficult to develop new ones: The KMSAN test failures bisect to the following commit: commit f90b474a35744b5d43009e4fab232e74a3024cae Author: Vlastimil Babka Date: Mon Mar 10 13:40:17 2025 +0100 mm: Fix the flipped condition in gfpflags_allow_spinning() I'm not sure why. Apparently something related to lib/stackdepot.c. Reverting that commit on top of upstream fixes the KMSAN tests. - Eric