[PATCH v2] bpf: core: fix shift-out-of-bounds in ___bpf_prog_run

Kurt Manucredo fuzzybritches0 at gmail.com
Fri Jun 4 21:15:30 UTC 2021


On Wed, 2 Jun 2021 09:36:45 +0300, Pavel Skripkin <paskripkin at gmail.com> wrote:
> 
> On Wed, 2 Jun 2021 08:09:48 +0200
> Greg KH <gregkh at linuxfoundation.org> wrote:
> 
> > On Tue, Jun 01, 2021 at 11:28:00PM +0200, Kurt Manucredo wrote:
> > > On Tue, 1 Jun 2021 17:43:24 +0200, Greg KH
> > > <gregkh at linuxfoundation.org> wrote:
> > > > 
> > > > On Tue, Jun 01, 2021 at 04:33:09PM +0200, Kurt Manucredo wrote:
> > > > > Fix shift-out-of-bounds in ___bpf_prog_run().
> > > > 
> > > > How is this "fixed"?
> > > > 
> > > Fix shift-out-of-bounds in ___bpf_prog_run() by adding extra
> > > boundary check in check_alu_op() in verifier.c.
> > 
> > Great, say this in the changelog text.
> > 
> > > > > 
> > > > > UBSAN: shift-out-of-bounds in kernel/bpf/core.c:1414:2
> > > > > shift exponent 248 is too large for 32-bit type 'unsigned int'
> > > > 
> > > > What is this from?
> > > 
> > > https://syzkaller.appspot.com/bug?id=edb51be4c9a320186328893287bb30d5eed09231
> > 
> > You should provide this link in the changelog text.
> > 
> > > > Any reason you didn't cc: the bpf maintainers and developers?
> > > > 
> > > Yes. I send them to you, the mentees mailing list and Shuah, first,
> > > for review, comment and help. Is this not okay? 
> > 
> > Ok, didn't know what you were wanting here, you can always ask
> > questions like this below the --- line of a patch.
> > 
> > > > > Reported-by:
> > > > > syzbot+bed360704c521841c85d at syzkaller.appspotmail.com
> > > > 
> > > > Does this pass the syzbot testing?
> > > 
> > > Yes, it says 'OK' in the 'Result' column at:
> > > https://syzkaller.appspot.com/bug?id=edb51be4c9a320186328893287bb30d5eed09231
> > 
> > You should also say something like "passes the syzbot reproducer test"
> > in the changelog text as well.
> > 
> 
> Other possible way to tell maintainer, that patch was tested
> somehow, is to change Reported-by to Reported-and-tested-by tag received
> from syzbot. It might be more nicely :)
> 

thanks Pavel

kind regards

Kurt Manucredo



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