sched/isolation: Defer freeing of cpumask memblock memory to initcall
- Published
- Last modified
- Where the record stands: published, rejected by its publisher, or superseded by another id.What do these mean? →
- published
- Whether CISA lists it in its Known Exploited Vulnerabilities catalog: proof that attackers are using it.What do these mean? →
- Not listed in CISA KEV
- Fix
- Fixed in 7.2.6
- Whether working attack code is public (Exploit-DB, Metasploit, Nuclei or GitHub). Public code makes attacks easier.What do these mean? →
- None on Exploit-DB, Metasploit or GitHub
Summary
In the Linux kernel, the following vulnerability has been resolved: sched/isolation: Defer freeing of cpumask memblock memory to initcall When testing a linux-next kernel with commit 59bd1d914bb5 ("memblock: warn when freeing reserved memory before memory map is initialized"), the following warning was hit when there was a "nohz_full" kernel boot parameter. Cannot free reserved memory because of deferred initialization of the memory map WARNING: mm/memblock.c:904 at __free_reserved_area+0xde/0xf0, CPU#0: swapper/0/0 : Call Trace: <TASK> memblock_phys_free+0xcb/0x100 housekeeping_init+0x14c/0x170 start_kernel+0x207/0x450 x86_64_start_reservations+0x24/0x30 x86_64_start_kernel+0xda/0xe0 common_startup_64+0x13e/0x141 </TASK> IOW, we shouldn't free memblock allocated memory so early in the boot process when memory map isn't fully initialized in deferred_init_memmap(). Fix it by saving the housekeeping cpumask memblock memory to be freed into a llist free list in housekeeping_init() and add a new housekeeping_late_init() helper to defer the actual freeing of memblock memory to when initcall's are being processed. The cpumask memblock memory is treated as a llist_node with the size of a "long" type which is also smallest cpumask size that can be allocated. The non-atomic version of the llist APIs are used as there is no contention. This commit depends on the presence of commit 7c2eee9c1367 ("memblock: don't touch memblock arrays when memblock_free() is called late") to prevent a KASAN UAF bug report [1]. [1] https://lore.kernel.org/lkml/20260505051821.1107133-1-longman@redhat.com/
Timeline
- CVE published
- Record last updated
Affected versions
- Linux Linux
From 27c3a5967f054ab666704cb28f2aeb18ca07cab7 · fixed in 811fdac2d1bdf0b0d3fda262aac288ddd13a1422; From 27c3a5967f054ab666704cb28f2aeb18ca07cab7 · fixed in 2b58c749b8c5244e259a0230bc57b10b010dc545
- Linux Linux
7.0
- KernelLinux
From 7.0.0 · fixed in 7.2.6