md: fix soft lockup in status_resync

Vulnerability Description

In the Linux kernel, the following vulnerability has been resolved: md: fix soft lockup in status_resync status_resync() will calculate 'curr_resync - recovery_active' to show user a progress bar like following: [============>........] resync = 61.4% 'curr_resync' and 'recovery_active' is updated in md_do_sync(), and status_resync() can read them concurrently, hence it's possible that 'curr_resync - recovery_active' can overflow to a huge number. In this case status_resync() will be stuck in the loop to print a large amount of '=', which will end up soft lockup. Fix the problem by setting 'resync' to MD_RESYNC_ACTIVE in this case, this way resync in progress will be reported to user.

References

• https://git.kernel.org/stable/c/b4acb6c3ede88d6b7d33742a09e63cfce5e7fb69
• https://git.kernel.org/stable/c/23309704e90859af2662bedc44101e6d1d2ece7e
• https://git.kernel.org/stable/c/6efddf1e32e2a264694766ca485a4f5e04ee82a7