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

Revert "md/raid5: Wait for MD_SB_CHANGE_PENDING in raid5d"

This reverts commit 5e2cf333b7bd5d3e62595a44d598a254c697cd74.

That commit introduced the following race and can cause system hung.

 md_write_start:             raid5d:
 // mddev->in_sync == 1
 set "MD_SB_CHANGE_PENDING"
                            // running before md_write_start wakeup it
                             waiting "MD_SB_CHANGE_PENDING" cleared
                             >>>>>>>>> hung
 wakeup mddev->thread
 ...
 waiting "MD_SB_CHANGE_PENDING" cleared
 >>>> hung, raid5d should clear this flag
 but get hung by same flag.

The issue reverted commit fixing is fixed by last patch in a new way.

Linux https://git.kernel.org/stable/c/0de40f76d567133b871cd6ad46bb87afbce46983 [No types assigned]

Linux https://git.kernel.org/stable/c/84c39986fe6dd77aa15f08712339f5d4eb7dbe27 [No types assigned]

Linux https://git.kernel.org/stable/c/87165c64fe1a98bbab7280c58df3c83be2c98478 [No types assigned]

Linux https://git.kernel.org/stable/c/aab69ef769707ad987ff905d79e0bd6591812580 [No types assigned]

Linux https://git.kernel.org/stable/c/bed0acf330b2c50c688f6d9cfbcac2aa57a8e613 [No types assigned]

Linux https://git.kernel.org/stable/c/bed9e27baf52a09b7ba2a3714f1e24e17ced386d [No types assigned]

Linux https://git.kernel.org/stable/c/cfa46838285814c3a27faacf7357f0a65bb5d152 [No types assigned]

Linux https://git.kernel.org/stable/c/e16a0bbdb7e590a6607b0d82915add738c03c069 [No types assigned]