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| Started by | Johan Hovold <johan@kernel.org> |
|---|---|
| First post | 2017-03-13 18:20 +0100 |
| Last post | 2017-03-15 08:40 +0100 |
| Articles | 2 — 2 participants |
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Re: [PATCH 4.4 17/25] USB: serial: digi_acceleport: fix OOB data sanity check Johan Hovold <johan@kernel.org> - 2017-03-13 18:20 +0100
Re: [PATCH 4.4 17/25] USB: serial: digi_acceleport: fix OOB data sanity check Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-03-15 08:40 +0100
| From | Johan Hovold <johan@kernel.org> |
|---|---|
| Date | 2017-03-13 18:20 +0100 |
| Subject | Re: [PATCH 4.4 17/25] USB: serial: digi_acceleport: fix OOB data sanity check |
| Message-ID | <tkBNw-3I1-27@gated-at.bofh.it> |
On Fri, Feb 24, 2017 at 06:55:02PM +0100, Greg Kroah-Hartman wrote:
> On Fri, Feb 24, 2017 at 06:33:04PM +0100, Johan Hovold wrote:
> > On Fri, Feb 24, 2017 at 01:38:25PM +0000, Ben Hutchings wrote: > On Fri, 2017-02-24 at 09:25 +0100, Greg Kroah-Hartman wrote:
> > > > 4.4-stable review patch. If anyone has any objections, please let me know.
> > > >
> > > > ------------------
> > > >
> > > > From: Johan Hovold <johan@kernel.org>
> > > >
> > > > commit 2d380889215fe20b8523345649dee0579821800c upstream.
> > > >
> > > > Make sure to check for short transfers to avoid underflow in a loop
> > > > condition when parsing the receive buffer.
> > > >
> > > > Also fix an off-by-one error in the incomplete sanity check which could
> > > > lead to invalid data being parsed.
> > >
> > > This appears to *introduce* an off-by-one. Which is not as serious as
> > > the underflow, but is still a regression.
> > >
> > > Suppose we have urb->actual_length == 4:
> > >
> > > [...]
> > > > - for (i = 0; i < urb->actual_length - 3;) {
> > >
> > > i < 1 is true, so we would run the loop once.
> > >
> > > > - opcode = ((unsigned char *)urb->transfer_buffer)[i++];
> > > > - line = ((unsigned char *)urb->transfer_buffer)[i++];
> > > > - status = ((unsigned char *)urb->transfer_buffer)[i++];
> > > > - val = ((unsigned char *)urb->transfer_buffer)[i++];
> > > > + for (i = 0; i < urb->actual_length - 4; i += 4) {
> > >
> > > i < 0 is false, so we now skip the loop.
> >
> > Good catch, thanks! The original loop condition was indeed correct
> > (modulo the missing underflow check), and I'll post a follow-up fix to
> > address this.
> >
> > > > + opcode = buf[i];
> > > > + line = buf[i + 1];
> > > > + status = buf[i + 2];
> > > > + val = buf[i + 3];
> >
> > You should probably not apply this one until after the follow-up is in
> > Linus' tree as this patch breaks TIOCMGET.
>
> Ok, I'll drop this one from the stable tree now. Remind me to pick this
> one up when the fixup hits Linus's tree.
The follow-up fix is now in Linus's tree so both this one:
2d380889215f ("USB: serial: digi_acceleport: fix OOB data sanity check")
and the follow-up:
2e46565cf622 ("USB: serial: digi_acceleport: fix OOB-event processing")
can now be applied to the stable trees.
Thanks,
Johan
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| From | Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
|---|---|
| Date | 2017-03-15 08:40 +0100 |
| Message-ID | <tlbHj-4pe-11@gated-at.bofh.it> |
| In reply to | #1599652 |
On Mon, Mar 13, 2017 at 06:14:37PM +0100, Johan Hovold wrote:
> On Fri, Feb 24, 2017 at 06:55:02PM +0100, Greg Kroah-Hartman wrote:
> > On Fri, Feb 24, 2017 at 06:33:04PM +0100, Johan Hovold wrote:
> > > On Fri, Feb 24, 2017 at 01:38:25PM +0000, Ben Hutchings wrote: > On Fri, 2017-02-24 at 09:25 +0100, Greg Kroah-Hartman wrote:
> > > > > 4.4-stable review patch. If anyone has any objections, please let me know.
> > > > >
> > > > > ------------------
> > > > >
> > > > > From: Johan Hovold <johan@kernel.org>
> > > > >
> > > > > commit 2d380889215fe20b8523345649dee0579821800c upstream.
> > > > >
> > > > > Make sure to check for short transfers to avoid underflow in a loop
> > > > > condition when parsing the receive buffer.
> > > > >
> > > > > Also fix an off-by-one error in the incomplete sanity check which could
> > > > > lead to invalid data being parsed.
> > > >
> > > > This appears to *introduce* an off-by-one. Which is not as serious as
> > > > the underflow, but is still a regression.
> > > >
> > > > Suppose we have urb->actual_length == 4:
> > > >
> > > > [...]
> > > > > - for (i = 0; i < urb->actual_length - 3;) {
> > > >
> > > > i < 1 is true, so we would run the loop once.
> > > >
> > > > > - opcode = ((unsigned char *)urb->transfer_buffer)[i++];
> > > > > - line = ((unsigned char *)urb->transfer_buffer)[i++];
> > > > > - status = ((unsigned char *)urb->transfer_buffer)[i++];
> > > > > - val = ((unsigned char *)urb->transfer_buffer)[i++];
> > > > > + for (i = 0; i < urb->actual_length - 4; i += 4) {
> > > >
> > > > i < 0 is false, so we now skip the loop.
> > >
> > > Good catch, thanks! The original loop condition was indeed correct
> > > (modulo the missing underflow check), and I'll post a follow-up fix to
> > > address this.
> > >
> > > > > + opcode = buf[i];
> > > > > + line = buf[i + 1];
> > > > > + status = buf[i + 2];
> > > > > + val = buf[i + 3];
> > >
> > > You should probably not apply this one until after the follow-up is in
> > > Linus' tree as this patch breaks TIOCMGET.
> >
> > Ok, I'll drop this one from the stable tree now. Remind me to pick this
> > one up when the fixup hits Linus's tree.
>
> The follow-up fix is now in Linus's tree so both this one:
>
> 2d380889215f ("USB: serial: digi_acceleport: fix OOB data sanity check")
>
> and the follow-up:
>
> 2e46565cf622 ("USB: serial: digi_acceleport: fix OOB-event processing")
>
> can now be applied to the stable trees.
Thanks, now queued up.
greg k-h
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