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 ebiggers@kernel.org 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: <TASK> __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+0x198/0xa00Any 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 vbabka@suse.cz 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