Hi, On Fri, 2020-09-25 at 15:06 +0200, Miroslav Benes wrote: > Hi Kristen, > > On Wed, 23 Sep 2020, Kristen Carlson Accardi wrote: > > > Function Granular Kernel Address Space Layout Randomization > > (fgkaslr) > > ----------------------------------------------------------------- > > ---- > > > > This patch set is an implementation of finer grained kernel address > > space > > randomization. It rearranges your kernel code at load time > > on a per-function level granularity, with only around a second > > added to > > boot time. > > I ran live patching kernel selftests on the patch set and everything > passed fine. > > However, we also use not-yet-upstream set of tests at SUSE for > testing > live patching [1] and one of them, klp_tc_12.sh, is failing. You > should be > able to run the set on upstream as is. > > The test uninterruptedly sleeps in a kretprobed function called by a > patched one. The current master without fgkaslr patch set reports > the > stack of the sleeping task as unreliable and live patching fails. > The > situation is different with fgkaslr (even with nofgkaslr on the > command > line). The stack is returned as reliable. It looks something like > > [<0>] __schedule+0x465/0xa40 > [<0>] schedule+0x55/0xd0 > [<0>] orig_do_sleep+0xb1/0x110 [klp_test_support_mod] > [<0>] swap_pages+0x7f/0x7f > > where the last entry is not reliable. I've seen > kretprobe_trampoline+0x0/0x4a and some other symbols there too. Since > the > patched function (orig_sleep_uninterruptible_set) is not on the > stack, > live patching succeeds, which is not intended. > > With kprobe setting removed, all works as expected. > > So I wonder if there is still some issue with ORC somewhere as you > mentioned in v4 thread. I'll investigate more next week, but wanted > to > report early. > > Regards > Miroslav > > [1] https://github.com/lpechacek/qa_test_klp Thanks for testing and reporting. I will grab your test and see what I can find.
