| Message ID | 20210818043035.1308062-3-keescook@chromium.org (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | USB: EHCI: Add register array bounds to HCS ports | expand |
On Tue, Aug 17, 2021 at 09:30:34PM -0700, Kees Cook wrote: > 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"? I suspect the 0x90 value in the comment is a typo for 0x80. > 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@linuxfoundation.org> > Cc: Al Cooper <alcooperx@gmail.com> > Cc: Alan Stern <stern@rowland.harvard.edu> > Cc: linux-usb@vger.kernel.org > Cc: bcm-kernel-feedback-list@broadcom.com > Suggested-by: Arnd Bergmann <arnd@arndb.de> > Fixes: 9df231511bd6 ("usb: ehci: Add new EHCI driver for Broadcom STB SoC's") > Signed-off-by: Kees Cook <keescook@chromium.org> > --- > 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 This last comment line is no longer necessary, thanks to the revised port definitions. And since it is actively misleading, with the 0x90 instead of 0x80, I think it should be removed entirely. > */ > - 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 Same here. > */ > - 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. > + */ This comment is entirely inappropriate. It's the sort of thing that belongs in the git history, not in the code. > + u32 brcm_insnreg[3]; Given the notation in the original comments, perhaps it would be better to define this as: struct { /* Broadcom proprietary registers */ u32 brcm_insnreg01; /* offset 0x84 */ u32 brcm_insnreg02; u32 brcm_insnreg03; }; I don't know. It would be nice to hear from somebody at Broadcom. Alan Stern > + }; > + > u32 reserved5[2]; > > /* USBMODE_EX: offset 0xc8 */ > -- > 2.30.2 >
On Wed, Aug 18, 2021 at 10:57:36AM -0400, Alan Stern wrote: > On Tue, Aug 17, 2021 at 09:30:34PM -0700, Kees Cook wrote: > > 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"? > > I suspect the 0x90 value in the comment is a typo for 0x80. That'd be my conclusion too. I've updated this for v2. > > > 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@linuxfoundation.org> > > Cc: Al Cooper <alcooperx@gmail.com> > > Cc: Alan Stern <stern@rowland.harvard.edu> > > Cc: linux-usb@vger.kernel.org > > Cc: bcm-kernel-feedback-list@broadcom.com > > Suggested-by: Arnd Bergmann <arnd@arndb.de> > > Fixes: 9df231511bd6 ("usb: ehci: Add new EHCI driver for Broadcom STB SoC's") > > Signed-off-by: Kees Cook <keescook@chromium.org> > > --- > > 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 > > This last comment line is no longer necessary, thanks to the revised > port definitions. And since it is actively misleading, with the 0x90 > instead of 0x80, I think it should be removed entirely. Done. > > > */ > > - 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 > > Same here. > > > */ > > - 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. > > + */ > > This comment is entirely inappropriate. It's the sort of thing that > belongs in the git history, not in the code. I wanted it to be easily discoverable, but since we've got a preferred result now, I'm dropping this and orienting against 0x80. > > > + u32 brcm_insnreg[3]; > > Given the notation in the original comments, perhaps it would be better > to define this as: > > struct { /* Broadcom proprietary registers */ > u32 brcm_insnreg01; /* offset 0x84 */ > u32 brcm_insnreg02; > u32 brcm_insnreg03; > }; Following the other register arrays, I'm going to keep an array for this, but adjust the numbering to start at 0 @ 0x80 so the code will poke offset 1 and 3. > I don't know. It would be nice to hear from somebody at Broadcom. Agreed. :) Thanks for the review!
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 */
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@linuxfoundation.org> Cc: Al Cooper <alcooperx@gmail.com> Cc: Alan Stern <stern@rowland.harvard.edu> Cc: linux-usb@vger.kernel.org Cc: bcm-kernel-feedback-list@broadcom.com Suggested-by: Arnd Bergmann <arnd@arndb.de> Fixes: 9df231511bd6 ("usb: ehci: Add new EHCI driver for Broadcom STB SoC's") Signed-off-by: Kees Cook <keescook@chromium.org> --- drivers/usb/host/ehci-brcm.c | 11 +++++------ include/linux/usb/ehci_def.h | 16 ++++++++++++++-- 2 files changed, 19 insertions(+), 8 deletions(-)