On Fri, Jan 14, 2022 at 8:41 AM Kumar Kartikeya Dwivedi <memxor@xxxxxxxxx> wrote: > > This adds a complete test case to ensure we never take references to > modules not in MODULE_STATE_LIVE, which can lead to UAF, and it also > ensures we never access btf->kfunc_set_tab in an inconsistent state. > > The test uses userfaultfd to artificially widen the race. > > When run on an unpatched kernel, it leads to the following splat: > > [root@(none) bpf]# ./test_progs -t bpf_mod_race/ksym > [ 55.498171] BUG: unable to handle page fault for address: fffffbfff802548b [ 55.499206] #PF: supervisor read access in kernel mode > [ 55.499855] #PF: error_code(0x0000) - not-present page > [ 55.500555] PGD a4fa9067 P4D a4fa9067 PUD a4fa5067 PMD 1b44067 PTE 0 > [ 55.501499] Oops: 0000 [#1] PREEMPT SMP KASAN NOPTI > [ 55.502195] CPU: 0 PID: 83 Comm: kworker/0:2 Tainted: G OE 5.16.0-rc4+ #151 [ 55.503388] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS ArchLinux 1.15.0-1 04/01/2014 The commit log was messed up in a few places. I've cleaned it up while applying. Thanks!
