On Mon, 2025-09-08 at 19:49 +0200, Paul Chaignon wrote: > On Wed, Aug 20, 2025 at 12:37:46PM -0700, Eduard Zingerman wrote: > > On Wed, 2025-08-20 at 13:34 +0200, Paul Chaignon wrote: > > > > [...] > > > > > I have a patch to potentially fix this, but I'm still testing it and > > > would prefer to send it separately as it doesn't really relate to my > > > current patchset. > > > > I'd like to bring this point again: this is a cat-and-mouse game. > > is_scalar_branch_taken() and regs_refine_cond_op() are essentially > > same operation and should be treated as such: produce register states > > for both branches and prune those that result in an impossible state. > > There is nothing wrong with this logically and we haven't got a single > > real bug from the invariant violations check if I remember correctly. > > > > Comparing the two functions, it looks like tricky cases are BPF_JE/JNE > > and BPF_JSET/JSET|BPF_X. However, given that regs_refine_cond_op() is > > called for a false branch with opcode reversed it looks like there is > > no issues with these cases. > > > > I'll give this a try. > > Hi Eduard, > > Did you get a chance to look into this? syzkaller came back (finally) > complaining about the remaining invariant violations: > https://lore.kernel.org/bpf/68bacb3e.050a0220.192772.018d.GAE@xxxxxxxxxx/ > If not, I can have a look at the end of the week. > > Paul Hi Paul, I have an unfinished branch here: https://github.com/kernel-patches/bpf/commit/ef2e080a58206e23e3a521d2942f9b4d58a8627c Don't like how it looks though. Planned on getting back to it this week. Please ping me if you'd start working on a fix. Thanks, Eduard
