CVE-2024-38598

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 - CPU#3 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 doesnt match array size still need to be fixed.

Weakness

The product does not properly acquire or release a lock on a resource, leading to unexpected resource state changes and behaviors.

Affected Software

Extended Description

Locking is a type of synchronization behavior that ensures that multiple independently-operating processes or threads do not interfere with each other when accessing the same resource. All processes/threads are expected to follow the same steps for locking. If these steps are not followed precisely - or if no locking is done at all - then another process/thread could modify the shared resource in a way that is not visible or predictable to the original process. This can lead to data or memory corruption, denial of service, etc.

Potential Mitigations

Related Attack Patterns

• https://cwe.mitre.org/data/definitions/25.html
• https://cwe.mitre.org/data/definitions/26.html
• https://cwe.mitre.org/data/definitions/27.html

References

• https://git.kernel.org/stable/c/3f5b73ef8fd6268cbc968b308d8eafe56fda97f3
• https://git.kernel.org/stable/c/43771597feba89a839c5f893716df88ae5c237ce
• https://git.kernel.org/stable/c/5817f43ae1a118855676f57ef7ab50e37eac7482
• https://git.kernel.org/stable/c/69296914bfd508c85935bf5f711cad9b0fe78492
• https://git.kernel.org/stable/c/71e8e4f288e74a896b6d9cd194f3bab12bd7a10f
• https://git.kernel.org/stable/c/8bbc71315e0ae4bb7e37f8d43b915e1cb01a481b
• https://git.kernel.org/stable/c/c9566b812c8f66160466cc1e29df6d3646add0b1
• https://git.kernel.org/stable/c/d4b9c764d48fa41caa24cfb4275f3aa9fb4bd798
• https://git.kernel.org/stable/c/f0e729af2eb6bee9eb58c4df1087f14ebaefe26b