Refactor struct ehci_regs to avoid accessing beyond the end of
port_status. This change results in no difference in the resulting
object code.
Avoids several warnings when building with -Warray-bounds:
drivers/usb/host/ehci-brcm.c: In function 'ehci_brcm_reset':
drivers/usb/host/ehci-brcm.c:113:32: warning: array subscript 16 is above array bounds of 'u32[15]' {aka 'unsigned int[15]'} [-Warray-bounds]
113 | ehci_writel(ehci, 0x00800040, &ehci->regs->port_status[0x10]);
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In file included from drivers/usb/host/ehci.h:274,
from drivers/usb/host/ehci-brcm.c:15:
./include/linux/usb/ehci_def.h:132:7: note: while referencing 'port_status'
132 | u32 port_status[HCS_N_PORTS_MAX];
| ^~~~~~~~~~~
Note that the documentation around this proprietary register is
confusing. If "USB_EHCI_INSNREG00" is at port_status[0x0f], its offset
would be 0x80 (not 0x90). The code uses port_status[0x10], so is that
not using "USB_EHCI_INSNREG00"?
Perhaps port_status[0x10] is USB_EHCI_INSNREG01 and port_status[0x12]
is USB_EHCI_INSNREG03? If so, the union could be adjusted to better
represent the layout.
Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Cc: Al Cooper <alcooperx@xxxxxxxxx>
Cc: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx>
Cc: linux-usb@xxxxxxxxxxxxxxx
Cc: bcm-kernel-feedback-list@xxxxxxxxxxxx
Suggested-by: Arnd Bergmann <arnd@xxxxxxxx>
Fixes: 9df231511bd6 ("usb: ehci: Add new EHCI driver for Broadcom STB SoC's")
Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx>
---
drivers/usb/host/ehci-brcm.c | 11 +++++------
include/linux/usb/ehci_def.h | 16 ++++++++++++++--
2 files changed, 19 insertions(+), 8 deletions(-)
diff --git a/drivers/usb/host/ehci-brcm.c b/drivers/usb/host/ehci-brcm.c
index 3e0ebe8cc649..5d232d3701f9 100644
--- a/drivers/usb/host/ehci-brcm.c
+++ b/drivers/usb/host/ehci-brcm.c
@@ -110,8 +110,8 @@ static int ehci_brcm_reset(struct usb_hcd *hcd)
* bus usage
* port_status[0x0f] = Broadcom-proprietary USB_EHCI_INSNREG00 @ 0x90
*/
- ehci_writel(ehci, 0x00800040, &ehci->regs->port_status[0x10]);
- ehci_writel(ehci, 0x00000001, &ehci->regs->port_status[0x12]);
+ ehci_writel(ehci, 0x00800040, &ehci->regs->brcm_insnreg[0]);
+ ehci_writel(ehci, 0x00000001, &ehci->regs->brcm_insnreg[2]);
return ehci_setup(hcd);
}
@@ -223,11 +223,10 @@ static int __maybe_unused ehci_brcm_resume(struct device *dev)
/*
* SWLINUX-1705: Avoid OUT packet underflows during high memory
* bus usage
- * port_status[0x0f] = Broadcom-proprietary USB_EHCI_INSNREG00
- * @ 0x90
+ * port_status[0x0f] = Broadcom-proprietary USB_EHCI_INSNREG00 @ 0x90
*/
- ehci_writel(ehci, 0x00800040, &ehci->regs->port_status[0x10]);
- ehci_writel(ehci, 0x00000001, &ehci->regs->port_status[0x12]);
+ ehci_writel(ehci, 0x00800040, &ehci->regs->brcm_insnreg[0]);
+ ehci_writel(ehci, 0x00000001, &ehci->regs->brcm_insnreg[2]);
ehci_resume(hcd, false);
diff --git a/include/linux/usb/ehci_def.h b/include/linux/usb/ehci_def.h
index 5398f571113b..86f0909cab99 100644
--- a/include/linux/usb/ehci_def.h
+++ b/include/linux/usb/ehci_def.h
@@ -182,11 +182,23 @@ struct ehci_regs {
* its EHCI controller has both TT and LPM support. HOSTPCx are extensions to
* PORTSCx
*/
- /* HOSTPC: offset 0x84 */
- u32 hostpc[HCS_N_PORTS_MAX];
+ union {
+ /* HOSTPC: offset 0x84 */
+ u32 hostpc[HCS_N_PORTS_MAX];
#define HOSTPC_PHCD (1<<22) /* Phy clock disable */
#define HOSTPC_PSPD (3<<25) /* Port speed detection */
+ /*
+ * This was originally documented as:
+ * "port_status[0x0f] = Broadcom-proprietary USB_EHCI_INSNREG00 @ 0x90"
+ * but this doesn't make sense: the code was using
+ * port_status[0x10]. port_status[0x0f] would be reserved4.
+ * Also, none of these are near 0x90. port_status[0x10] is
+ * offset 0x84, and port_status[0x0f] would be 0x80.
+ */
+ u32 brcm_insnreg[3];
+ };
+
u32 reserved5[2];
/* USBMODE_EX: offset 0xc8 */
--
2.30.2
