Thread (11 messages) 11 messages, 3 authors, 2021-12-02

Re: [PATCH v2] arm64: Enable KCSAN

From: Marco Elver <elver@google.com>
Date: 2021-12-02 10:20:10
Also in: lkml

On Thu, 2 Dec 2021 at 11:16, Marco Elver [off-list ref] wrote:
[...]
quoted
Reported by Kernel Concurrency Sanitizer on:
CPU: 7 PID: 2530 Comm: syz-executor.11 Not tainted 5.10.0+ #113
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.13.0-1ubuntu1.104/01/2014
==================================================================
BUG: KCSAN: data-race in rwsem_spin_on_owner+0xf4/0x180

race at unknown origin, with read to 0xffff9767d3becfac of 4 bytes by task 18119 on cpu 0:
 rwsem_spin_on_owner+0xf4/0x180
 rwsem_optimistic_spin+0x48/0x480
 rwsem_down_read_slowpath+0x4a0/0x670
 down_read+0x69/0x190
 process_vm_rw+0x41e/0x840
 __x64_sys_process_vm_writev+0x76/0x90
 do_syscall_64+0x37/0x50
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
[...]
I actually have a "fix" for the data race in rwsem_spin_on_owner, that
also shows where the other racing access comes from... which reminds me:
https://lkml.kernel.org/r/20211202101238.33546-1-elver@google.com
Reading be hard ... that patch is for mutex_spin_on_owner. But the
other racing access is the same.

Thanks,
-- Marco

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