CVE-2026-90389md: scope memalloc_noio to allocation critical sections

Official description

In the Linux kernel, the following vulnerability has been resolved: md: scope memalloc_noio to allocation critical sections Storing a memalloc_noio_save() token in mddev->noio_flags lets one task save the token and another task restore it. With concurrent suspend sysfs writes, task A can enter PF_MEMALLOC_NOIO, return to userspace still in that scope, and later task B can restore A's saved token. Avoid tying the token lifetime to mddev. Keep mddev_suspend() and mddev_resume() only responsible for array suspension, and enter PF_MEMALLOC_NOIO only in the MD paths that allocate memory after the array has been suspended. Restore the token before resuming the array. A reproducer repeatedly writes suspend_lo and suspend_hi from concurrent workers and checks each worker's /proc/self/stat flags before and after the sysfs write.

Affected packages & fixed versions

Affected products (as reported)

References

• https://git.kernel.org/stable/c/72ebfdf507ede7d7f2b7ca0a5634811a0e4bf045
• https://git.kernel.org/stable/c/28fdea874f68cac6c36651b1fc7272fd2199c48d
• https://git.kernel.org/stable/c/a58923756b0f8e71032070c23ae0b167e46731da
• https://git.kernel.org/stable/c/bace2010dd7ac07bc980575afb135c406730a7fe