In the Linux kernel, the following vulnerability has been resolved:
LoongArch: Fix panic caused by NULL-PMD in hugepteoffset()
ERROR INFO:
CPU 25 Unable to handle kernel paging request at virtual address 0x0 ... Call Trace: [<900000000023c30c>] hugepteoffset+0x3c/0x58 [<900000000057fd4c>] hugetlbfollowpagemask+0x74/0x438 [<900000000051fee8>] _getuserpages+0xe0/0x4c8 [<9000000000522414>] faultinpagerange+0x84/0x380 [<9000000000564e8c>] madvisevmabehavior+0x534/0xa48 [<900000000056689c>] domadvise+0x1bc/0x3e8 [<9000000000566df4>] sysmadvise+0x24/0x38 [<90000000015b9e88>] dosyscall+0x78/0x98 [<9000000000221f18>] handlesyscall+0xb8/0x158
In some cases, pmd may be NULL and rely on NULL as the return value for processing, so it is necessary to determine this situation here.