In the Linux kernel, the following vulnerability has been resolved: nfsd: return -EINVAL when namelen is 0 When we have a corrupted main.sqlite in /var/lib/nfs/nfsdcld/, it may result in namelen being 0, which will cause memdup_user() to return ZERO_SIZE_PTR. When we access the name.data that has been assigned the value of ZERO_SIZE_PTR in nfs4_client_to_reclaim(), null pointer dereference is triggered. [ T1205] ================================================================== [ T1205] BUG: KASAN: null-ptr-deref in nfs4_client_to_reclaim+0xe9/0x260 [ T1205] Read of size 1 at addr 0000000000000010 by task nfsdcld/1205 [ T1205] [ T1205] CPU: 11 PID: 1205 Comm: nfsdcld Not tainted 5.10.0-00003-g2c1423731b8d #406 [ T1205] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS ?-20190727_073836-buildvm-ppc64le-16.ppc.fedoraproject.org-3.fc31 04/01/2014 [ T1205] Call Trace: [ T1205] dump_stack+0x9a/0xd0 [ T1205] ? nfs4_client_to_reclaim+0xe9/0x260 [ T1205] __kasan_report.cold+0x…