Messages in this thread | | | Date | Mon, 5 Sep 2022 23:14:30 +0800 | Subject | Re: [PATCH] erofs: fix pcluster use-after-free on UP platforms | From | Chao Yu <> |
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On 2022/9/2 12:57, Gao Xiang wrote: > During stress testing with CONFIG_SMP disabled, KASAN reports as below: > > ================================================================== > BUG: KASAN: use-after-free in __mutex_lock+0xe5/0xc30 > Read of size 8 at addr ffff8881094223f8 by task stress/7789 > [ 3482.258885] > CPU: 0 PID: 7789 Comm: stress Not tainted 6.0.0-rc1-00002-g0d53d2e882f9 #3 > Hardware name: Red Hat KVM, BIOS 0.5.1 01/01/2011 > Call Trace: > <TASK> > .. > __mutex_lock+0xe5/0xc30 > .. > z_erofs_do_read_page+0x8ce/0x1560 > .. > z_erofs_readahead+0x31c/0x580 > .. > Freed by task 7787 > kasan_save_stack+0x1e/0x40 > kasan_set_track+0x20/0x30 > kasan_set_free_info+0x20/0x40 > __kasan_slab_free+0x10c/0x190 > kmem_cache_free+0xed/0x380 > rcu_core+0x3d5/0xc90 > __do_softirq+0x12d/0x389 > [ 3482.295630] > Last potentially related work creation: > kasan_save_stack+0x1e/0x40 > __kasan_record_aux_stack+0x97/0xb0 > call_rcu+0x3d/0x3f0 > erofs_shrink_workstation+0x11f/0x210 > erofs_shrink_scan+0xdc/0x170 > shrink_slab.constprop.0+0x296/0x530 > drop_slab+0x1c/0x70 > drop_caches_sysctl_handler+0x70/0x80 > proc_sys_call_handler+0x20a/0x2f0 > vfs_write+0x555/0x6c0 > ksys_write+0xbe/0x160 > do_syscall_64+0x3b/0x90 > > The root cause is that erofs_workgroup_unfreeze() doesn't reset > to orig_val thus it causes a race that the pcluster reuses unexpectedly > before freeing. > > Since UP platforms are quite rare now, such path becomes unnecessary. > Let's drop such specific-designed path directly instead. > > Fixes: 73f5c66df3e2 ("staging: erofs: fix `erofs_workgroup_{try_to_freeze, unfreeze}'") > Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Reviewed-by: Chao Yu <chao@kernel.org>
Thanks,
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