2022-03-04 20:29:23

by Peter Zijlstra

Subject: [PATCH 3/3] usb: early: xhci-dbc: Fix xdbc number parsing

kstrtoul() assumes the string contains the number only and is \0
terminated, this is not the case, as such things like:

earlyprintk=xdbc1,keep

go completely sideways. Use simple_strtoul() instead.

Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
---
drivers/usb/early/xhci-dbc.c | 8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-)

--- a/drivers/usb/early/xhci-dbc.c
+++ b/drivers/usb/early/xhci-dbc.c
@@ -603,6 +603,7 @@ int __init early_xdbc_parse_parameter(ch
{
unsigned long dbgp_num = 0;
u32 bus, dev, func, offset;
+ char *e;
int ret;

if (!early_pci_allowed())
@@ -613,8 +614,11 @@ int __init early_xdbc_parse_parameter(ch
if (xdbc.xdbc_reg)
return 0;

- if (*s && kstrtoul(s, 0, &dbgp_num))
- dbgp_num = 0;
+ if (*s) {
+ dbgp_num = simple_strtoul(s, &e, 10);
+ if (s == e)
+ dbgp_num = 0;
+ }

pr_notice("dbgp_num: %lu\n", dbgp_num);

2022-03-08 13:05:02

by Mathias Nyman

Subject: Re: [PATCH 3/3] usb: early: xhci-dbc: Fix xdbc number parsing

On 4.3.2022 17.19, Peter Zijlstra wrote:
> kstrtoul() assumes the string contains the number only and is \0
> terminated, this is not the case, as such things like:
>
> earlyprintk=xdbc1,keep
>
> go completely sideways. Use simple_strtoul() instead.
>
> Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
> ---
> drivers/usb/early/xhci-dbc.c | 8 ++++++--
> 1 file changed, 6 insertions(+), 2 deletions(-)
>
> --- a/drivers/usb/early/xhci-dbc.c
> +++ b/drivers/usb/early/xhci-dbc.c
> @@ -603,6 +603,7 @@ int __init early_xdbc_parse_parameter(ch
> {
> unsigned long dbgp_num = 0;
> u32 bus, dev, func, offset;
> + char *e;
> int ret;
>
> if (!early_pci_allowed())
> @@ -613,8 +614,11 @@ int __init early_xdbc_parse_parameter(ch
> if (xdbc.xdbc_reg)
> return 0;
>
> - if (*s && kstrtoul(s, 0, &dbgp_num))
> - dbgp_num = 0;
> + if (*s) {

Do you think we need a code comment here stating something like
"use deprecated simple_strtoul() as kstrtoul can't handle characters after the number"

> + dbgp_num = simple_strtoul(s, &e, 10);
> + if (s == e)
> + dbgp_num = 0;
> + }
>

If not then PATCH 2/3 and 3/3 looks good to me
I don't know much about PATCH 1/3, the tsc change, but it didn't cause any issues for me either.

Acked-by: Mathias Nyman <[email protected]>

Thanks
-Mathias