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.
> [ 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
