On Thu, Sep 3, 2020 at 4:10 AM Heikki Krogerus
<heikki.krogerus@xxxxxxxxxxxxxxx> wrote:
>
> Hi Zwane,
>
> Sorry to keep you waiting. I'm trying to find a board I can use to
> test these...
>
> On Sun, Aug 30, 2020 at 02:26:36AM -0700, Zwane Mwaikambo wrote:
> > con->partner_altmode[i] ends up with the value 0x2 in the call to
> > typec_altmode_update_active because the array has been accessed out of
> > bounds causing a random memory read.
> >
> > This patch fixes the first occurrence and 2/2 the second.
>
> That, when read from the final commit log, does not actually tell you
> anything.
True :( I can resend a v6 to fix that if needed.
Thanks!
>
> > [ 565.452023] BUG: kernel NULL pointer dereference, address: 00000000000002fe
> > [ 565.452025] #PF: supervisor read access in kernel mode
> > [ 565.452026] #PF: error_code(0x0000) - not-present page
> > [ 565.452026] PGD 0 P4D 0
> > [ 565.452028] Oops: 0000 [#1] PREEMPT SMP NOPTI
> > [ 565.452030] CPU: 0 PID: 502 Comm: kworker/0:3 Not tainted 5.8.0-rc3+ #1
> > [ 565.452031] Hardware name: LENOVO 20RD002VUS/20RD002VUS,
> > BIOS R16ET25W (1.11 ) 04/21/2020
> > [ 565.452034] Workqueue: events ucsi_handle_connector_change [typec_ucsi]
> > [ 565.452039] RIP: 0010:typec_altmode_update_active+0x1f/0x100 [typec]
> > [ 565.452040] Code: 0f 1f 84 00 00 00 00 00 0f 1f 00 0f 1f 44 00 00 55 48
> > 89 e5 41 54 53 48 83 ec 10 65 48 8b 04 25 28 00 00 00 48 89 45 e8 31 c0
> > <0f> b6 87 fc 02 00 00 83 e0 01 40 38 f0 0f 84 95 00 00 00 48 8b 47
> > [ 565.452041] RSP: 0018:ffffb729c066bdb0 EFLAGS: 00010246
> > [ 565.452042] RAX: 0000000000000000 RBX: ffffa067c3e64a70 RCX: 0000000000000000
> > [ 565.452043] RDX: ffffb729c066bd20 RSI: 0000000000000000 RDI: 0000000000000002
> > [ 565.452044] RBP: ffffb729c066bdd0 R08: 00000083a7910a4f R09: 0000000000000000
> > [ 565.452044] R10: ffffffffa106a220 R11: 0000000000000000 R12: 0000000000000000
> > [ 565.452045] R13: ffffa067c3e64a98 R14: ffffa067c3e64810 R15: ffffa067c3e64800
> > [ 565.452046] FS: 0000000000000000(0000) GS:ffffa067d1400000(0000)
> > knlGS:0000000000000000
> > [ 565.452047] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> > [ 565.452048] CR2: 00000000000002fe CR3: 00000001b060a003 CR4: 00000000003606f0
> > [ 565.452048] Call Trace:
> > [ 565.452052] ucsi_altmode_update_active+0x83/0xd0 [typec_ucsi]
> > [ 565.452054] ucsi_handle_connector_change+0x1dc/0x320 [typec_ucsi]
> > [ 565.452057] process_one_work+0x1df/0x3d0
> > [ 565.452059] worker_thread+0x4d/0x3d0
> > [ 565.452060] ? process_one_work+0x3d0/0x3d0
> > [ 565.452062] kthread+0x127/0x170
> > [ 565.452063] ? kthread_park+0x90/0x90
> > [ 565.452065] ret_from_fork+0x1f/0x30
> >
> > The failing instruction is;
> >
> > 0x0000000000000380 <+0>: callq 0x385 <typec_altmode_update_active+5>
> > 0x0000000000000385 <+5>: push %rbp
> > 0x0000000000000386 <+6>: mov %rsp,%rbp
> > 0x0000000000000389 <+9>: push %r12
> > 0x000000000000038b <+11>: push %rbx
> > 0x000000000000038c <+12>: sub $0x10,%rsp
> > 0x0000000000000390 <+16>: mov %gs:0x28,%rax
> > 0x0000000000000399 <+25>: mov %rax,-0x18(%rbp)
> > 0x000000000000039d <+29>: xor %eax,%eax
> > 0x000000000000039f <+31>: movzbl 0x2fc(%rdi),%eax <======
> > 0x00000000000003a6 <+38>: and $0x1,%eax
> >
> > (gdb) list *typec_altmode_update_active+0x1f
> > 0x39f is in typec_altmode_update_active (drivers/usb/typec/class.c:221).
> > 216 */
> > 217 void typec_altmode_update_active(struct typec_altmode *adev, bool active)
> > 218 {
> > 219 char dir[6];
> > 220
> > 221 if (adev->active == active)
> > 222 return;
> > 223
> > 224 if (!is_typec_port(adev->dev.parent) && adev->dev.driver) {
> > 225 if (!active)
> >
> > (gdb) list *ucsi_altmode_update_active+0x83
> > 0x12a3 is in ucsi_altmode_update_active (drivers/usb/typec/ucsi/ucsi.c:221).
> > 216 }
> > 217
> > 218 if (cur < UCSI_MAX_ALTMODES)
> > 219 altmode = typec_altmode_get_partner(con->port_altmode[cur]);
> > 220
> > 221 for (i = 0; con->partner_altmode[i]; i++)
> > 222 typec_altmode_update_active(con->partner_altmode[i],
> > 223 con->partner_altmode[i] == altmode);
> > 224 }
> >
> > Fixes: ad74b8649beaf ("usb: typec: ucsi: Preliminary support for alternate modes")
> > Cc: stable@xxxxxxxxxxxxxxx
> > Signed-off-by: Zwane Mwaikambo <zwane@xxxxxxxxx>
> > ---
> > v2 addresses both instances of array overrun
> > v3 addresses patch submission/formatting issues
> > v4 addresses patch submission/formatting issues
> > v5 adds and cc to stable
> >
> > diff --git a/drivers/usb/typec/ucsi/ucsi.c b/drivers/usb/typec/ucsi/ucsi.c
> > index affd024190c9..16906519c173 100644
> > --- a/drivers/usb/typec/ucsi/ucsi.c
> > +++ b/drivers/usb/typec/ucsi/ucsi.c
> > @@ -218,9 +218,10 @@ void ucsi_altmode_update_active(struct ucsi_connector *con)
> > if (cur < UCSI_MAX_ALTMODES)
> > altmode = typec_altmode_get_partner(con->port_altmode[cur]);
> >
> > - for (i = 0; con->partner_altmode[i]; i++)
> > - typec_altmode_update_active(con->partner_altmode[i],
> > - con->partner_altmode[i] == altmode);
> > + for (i = 0; i < UCSI_MAX_ALTMODES; i++)
> > + if (con->partner_altmode[i])
> > + typec_altmode_update_active(con->partner_altmode[i],
> > + con->partner_altmode[i] == altmode);
> > }
> >
> > static u8 ucsi_altmode_next_mode(struct typec_altmode **alt, u16 svid)
> >
>
> thanks,
>
> --
> heikki
