CVE-2024-50199

In the Linux kernel, the following vulnerability has been resolved:<br /> <br /> mm/swapfile: skip HugeTLB pages for unuse_vma<br /> <br /> I got a bad pud error and lost a 1GB HugeTLB when calling swapoff. The<br /> problem can be reproduced by the following steps:<br /> <br /> 1. Allocate an anonymous 1GB HugeTLB and some other anonymous memory.<br /> 2. Swapout the above anonymous memory.<br /> 3. run swapoff and we will get a bad pud error in kernel message:<br /> <br /> mm/pgtable-generic.c:42: bad pud 00000000743d215d(84000001400000e7)<br /> <br /> We can tell that pud_clear_bad is called by pud_none_or_clear_bad in<br /> unuse_pud_range() by ftrace. And therefore the HugeTLB pages will never<br /> be freed because we lost it from page table. We can skip HugeTLB pages<br /> for unuse_vma to fix it.