Messages in this thread | | | From | Alexander Potapenko <> | Date | Thu, 18 Apr 2024 09:58:48 +0200 | Subject | Re: [syzbot] [mm?] KMSAN: kernel-infoleak in bpf_probe_write_user |
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On Tue, Apr 16, 2024 at 5:16 PM Alexei Starovoitov <alexei.starovoitov@gmail.com> wrote: > > On Tue, Apr 16, 2024 at 1:52 AM Alexander Potapenko <glider@google.com> wrote: > > > > On Mon, Apr 15, 2024 at 11:06 PM Alexei Starovoitov > > <alexei.starovoitov@gmail.com> wrote: > > > > > > Hi, > > > > > > syzbot folks, please disable such "bug" reporting. > > > The whole point of bpf is to pass such info to userspace. > > > probe_write_user, various ring buffers, bpf_*_printk-s, bpf maps > > > all serve this purpose of "infoleak". > > > > > > > Hi Alexei, > > > > From KMSAN's perspective it is fine to pass information to the > > userspace, unless it is marked as uninitialized. > > It could be that we are missing some initialization in kernel/bpf/core.c though. > > Do you know which part of the code is supposed to initialize the stack > > in PROG_NAME? > > cap_bpf + cap_perfmon bpf program are allowed to read uninitialized stack.
Out of curiosity, is this feature supposed to be used in production kernels?
> And recently we added > commit e8742081db7d ("bpf: Mark bpf prog stack with > kmsan_unposion_memory in interpreter mode") > to shut up syzbot.
I checked that the report in question is not reproducible with this patch anymore. Let's just wait until it reaches the mainline.
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