CVE-2024-38598 Information

Jun 20, 2024 cve

Description

In the Linux kernel the following vulnerability has been resolved:

md: fix resync softlockup when bitmap size is less than array size

Is is reported that for dm-raid10 lvextend + lvchange –syncaction will trigger following softlockup:

kernel:watchdog: BUG: soft lockup - CPU3 stuck for 26s! [mdX_resync:6976] CPU: 7 PID: 3588 Comm: mdX_resync Kdump: loaded Not tainted 6.9.0-rc4-next-20240419 1 RIP: 0010:_raw_spin_unlock_irq+0x13/0x30 Call Trace: md_bitmap_start_sync+0x6b/0xf0 raid10_sync_request+0x25c/0x1b40 [raid10] md_do_sync+0x64b/0x1020 md_thread+0xa7/0x170 kthread+0xcf/0x100 ret_from_fork+0x30/0x50 ret_from_fork_asm+0x1a/0x30

And the detailed process is as follows:

md_do_sync j = mddev->resync_min while (j < max_sectors) sectors = raid10_sync_request(mddev j &skipped) if (!md_bitmap_start_sync(… &sync_blocks)) // md_bitmap_start_sync set sync_blocks to 0 return sync_blocks + sectors_skippe; // sectors = 0; j += sectors; // j never change

Root cause is that commit 301867b1c168 (\md/raid10: check slab-out-of-bounds in md_bitmap_get_counter) return early from md_bitmap_get_counter() without setting returned blocks.

Fix this problem by always set returned blocks from md_bitmap_get_counter() as it used to be.

Noted that this patch just fix the softlockup problem in kernel the case that bitmap size doesn’t match array size still need to be fixed.

Reference

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