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Vulnerability CVE-2024-26899
Published: 2024-04-17
| Description: |
In the Linux kernel, the following vulnerability has been resolved:
block: fix deadlock between bd_link_disk_holder and partition scan
'open_mutex' of gendisk is used to protect open/close block devices. But
in bd_link_disk_holder(), it is used to protect the creation of symlink
between holding disk and slave bdev, which introduces some issues.
When bd_link_disk_holder() is called, the driver is usually in the process
of initialization/modification and may suspend submitting io. At this
time, any io hold 'open_mutex', such as scanning partitions, can cause
deadlocks. For example, in raid:
T1 T2
bdev_open_by_dev
lock open_mutex [1]
...
efi_partition
...
md_submit_bio
md_ioctl mddev_syspend
-> suspend all io
md_add_new_disk
bind_rdev_to_array
bd_link_disk_holder
try lock open_mutex [2]
md_handle_request
-> wait mddev_resume
T1 scan partition, T2 add a new device to raid. T1 waits for T2 to resume
mddev, but T2 waits for open_mutex held by T1. Deadlock occurs.
Fix it by introducing a local mutex 'blk_holder_mutex' to replace
'open_mutex'. |
References: |
https://git.kernel.org/stable/c/1e5c5b0abaee7b62a10b9707a62083b71ad21f62
https://git.kernel.org/stable/c/5a87c1f7993bc8ac358a3766bac5dc7126e01e98
https://git.kernel.org/stable/c/03f12122b20b6e6028e9ed69030a49f9cffcbb75
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