CVE-2022-50092

In the Linux kernel, the following vulnerability has been resolved:

dm thin: fix use-after-free crash in dm_sm_register_threshold_callback

Fault inject on pool metadata device reports: BUG: KASAN: use-after-free in dm_pool_register_metadata_threshold+0x40/0x80 Read of size 8 at addr ffff8881b9d50068 by task dmsetup/950

CPU: 7 PID: 950 Comm: dmsetup Tainted: G W 5.19.0-rc6 #1 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.14.0-1.fc33 04/01/2014 Call Trace: dump_stack_lvl+0x34/0x44 print_address_description.constprop.0.cold+0xeb/0x3f4 kasan_report.cold+0xe6/0x147 dm_pool_register_metadata_threshold+0x40/0x80 pool_ctr+0xa0a/0x1150 dm_table_add_target+0x2c8/0x640 table_load+0x1fd/0x430 ctl_ioctl+0x2c4/0x5a0 dm_ctl_ioctl+0xa/0x10 __x64_sys_ioctl+0xb3/0xd0 do_syscall_64+0x35/0x80 entry_SYSCALL_64_after_hwframe+0x46/0xb0

This can be easily reproduced using: echo offline > /sys/block/sda/device/state dd if=/dev/zero of=/dev/mapper/thin bs=4k count=10 dmsetup load pool –table 0 20971520 thin-pool /dev/sda /dev/sdb 128 0 0

If a metadata commit fails, the transaction will be aborted and the metadata space maps will be destroyed. If a DM table reload then happens for this failed thin-pool, a use-after-free will occur in dm_sm_register_threshold_callback (called from dm_pool_register_metadata_threshold).

Fix this by in dm_pool_register_metadata_threshold() by returning the -EINVAL error if the thin-pool is in fail mode. Also fail pool_ctr() with a new error message: Error registering metadata threshold.

Weakness

The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory “belongs” to the code that operates on the new pointer.

Affected Software

Potential Mitigations

References

• https://git.kernel.org/stable/c/05cef0999b3208b5a6ede1bfac855139e4de55ef
• https://git.kernel.org/stable/c/1a199fa9217d28511ff88529238fd9980ea64cf3
• https://git.kernel.org/stable/c/3534e5a5ed2997ca1b00f44a0378a075bd05e8a3
• https://git.kernel.org/stable/c/5e2cf705155a1514be3c96ea664a9cd356998ee7
• https://git.kernel.org/stable/c/e4dbe24f4bfd8377e7ba79fdcdb7c4d6eb1c6790
• https://git.kernel.org/stable/c/f83131a3071a0b61a4d7dca70f95adb3ffad920e