Hi Kees,
Thank you for the patch.
On Wed, Jun 16, 2021 at 11:59:38AM -0700, Kees Cook wrote:
> Avoid writing past the end of a structure member by wrapping the target
> region in a common named structure. This additionally fixes a
> misalignment of the copy (since the size of "buf" changes between 64-bit
> and 32-bit).
Could you have been mislead by the data64 name ? The difference between
omap3isp_stat_data_time and omap3isp_stat_data_time32 is the size of the
ts field, using 32-bit timestamps with legacy userspace, and 64-bit
timestamps with more recent userspace. In both cases we're dealing with
a 32-bit platform, as the omap3isp is not used in any 64-bit ARM SoC.
The size of void __user *buf is thus 4 bytes in all cases, as is __u32
buf.
> I actually think this code is completely unused in the real world:
> I don't think it could have ever worked, as it would either always
> fail (with an uninitialized data->buf_size) or would cause corruption
> in userspace due to the copy_to_user() in the call path against an
> uninitialized data->buf value:
>
> omap3isp_stat_request_statistics_time32(...)
> struct omap3isp_stat_data data64;
> ...
> omap3isp_stat_request_statistics(stat, &data64);
>
> int omap3isp_stat_request_statistics(struct ispstat *stat,
> struct omap3isp_stat_data *data)
> ...
> buf = isp_stat_buf_get(stat, data);
>
> static struct ispstat_buffer *isp_stat_buf_get(struct ispstat *stat,
> struct omap3isp_stat_data *data)
> ...
> if (buf->buf_size > data->buf_size) {
> ...
> return ERR_PTR(-EINVAL);
> }
> ...
> rval = copy_to_user(data->buf,
> buf->virt_addr,
> buf->buf_size);
>
> Regardless, additionally initialize data64 to be zero-filled to avoid
> undefined behavior.
>
> Fixes: 378e3f81cb56 ("media: omap3isp: support 64-bit version of omap3isp_stat_data")
> Signed-off-by: Kees Cook <[email protected]>
> ---
> drivers/media/platform/omap3isp/ispstat.c | 5 +--
> include/uapi/linux/omap3isp.h | 44 +++++++++++++++++------
> 2 files changed, 36 insertions(+), 13 deletions(-)
>
> diff --git a/drivers/media/platform/omap3isp/ispstat.c b/drivers/media/platform/omap3isp/ispstat.c
> index 5b9b57f4d9bf..ea8222fed38e 100644
> --- a/drivers/media/platform/omap3isp/ispstat.c
> +++ b/drivers/media/platform/omap3isp/ispstat.c
> @@ -512,7 +512,7 @@ int omap3isp_stat_request_statistics(struct ispstat *stat,
> int omap3isp_stat_request_statistics_time32(struct ispstat *stat,
> struct omap3isp_stat_data_time32 *data)
> {
> - struct omap3isp_stat_data data64;
> + struct omap3isp_stat_data data64 = { };
> int ret;
>
> ret = omap3isp_stat_request_statistics(stat, &data64);
> @@ -521,7 +521,8 @@ int omap3isp_stat_request_statistics_time32(struct ispstat *stat,
>
> data->ts.tv_sec = data64.ts.tv_sec;
> data->ts.tv_usec = data64.ts.tv_usec;
> - memcpy(&data->buf, &data64.buf, sizeof(*data) - sizeof(data->ts));
> + data->buf = (uintptr_t)data64.buf;
> + memcpy(&data->frame, &data64.buf, sizeof(data->frame));
>
> return 0;
> }
> diff --git a/include/uapi/linux/omap3isp.h b/include/uapi/linux/omap3isp.h
> index 87b55755f4ff..0a16af91621f 100644
> --- a/include/uapi/linux/omap3isp.h
> +++ b/include/uapi/linux/omap3isp.h
> @@ -159,13 +159,25 @@ struct omap3isp_h3a_aewb_config {
> };
>
> /**
> - * struct omap3isp_stat_data - Statistic data sent to or received from user
> - * @ts: Timestamp of returned framestats.
> - * @buf: Pointer to pass to user.
> + * struct omap3isp_stat_frame - Statistic data without timestamp nor pointer.
> + * @buf_size: Size of buffer.
> * @frame_number: Frame number of requested stats.
> * @cur_frame: Current frame number being processed.
> * @config_counter: Number of the configuration associated with the data.
> */
> +struct omap3isp_stat_frame {
> + __u32 buf_size;
> + __u16 frame_number;
> + __u16 cur_frame;
> + __u16 config_counter;
> +};
> +
> +/**
> + * struct omap3isp_stat_data - Statistic data sent to or received from user
> + * @ts: Timestamp of returned framestats.
> + * @buf: Pointer to pass to user.
> + * @frame: Statistic data for frame.
> + */
> struct omap3isp_stat_data {
> #ifdef __KERNEL__
> struct {
> @@ -176,10 +188,15 @@ struct omap3isp_stat_data {
> struct timeval ts;
> #endif
> void __user *buf;
> - __u32 buf_size;
> - __u16 frame_number;
> - __u16 cur_frame;
> - __u16 config_counter;
> + union {
> + struct {
> + __u32 buf_size;
> + __u16 frame_number;
> + __u16 cur_frame;
> + __u16 config_counter;
> + };
> + struct omap3isp_stat_frame frame;
> + };
> };
>
> #ifdef __KERNEL__
> @@ -189,10 +206,15 @@ struct omap3isp_stat_data_time32 {
> __s32 tv_usec;
> } ts;
> __u32 buf;
> - __u32 buf_size;
> - __u16 frame_number;
> - __u16 cur_frame;
> - __u16 config_counter;
> + union {
> + struct {
> + __u32 buf_size;
> + __u16 frame_number;
> + __u16 cur_frame;
> + __u16 config_counter;
> + };
> + struct omap3isp_stat_frame frame;
> + };
> };
> #endif
>
--
Regards,
Laurent Pinchart
On Wed, Jun 16, 2021 at 10:43:03PM +0300, Laurent Pinchart wrote:
> Hi Kees,
>
> Thank you for the patch.
>
> On Wed, Jun 16, 2021 at 11:59:38AM -0700, Kees Cook wrote:
> > Avoid writing past the end of a structure member by wrapping the target
> > region in a common named structure. This additionally fixes a
> > misalignment of the copy (since the size of "buf" changes between 64-bit
> > and 32-bit).
>
> Could you have been mislead by the data64 name ? The difference between
> omap3isp_stat_data_time and omap3isp_stat_data_time32 is the size of the
> ts field, using 32-bit timestamps with legacy userspace, and 64-bit
> timestamps with more recent userspace. In both cases we're dealing with
> a 32-bit platform, as the omap3isp is not used in any 64-bit ARM SoC.
> The size of void __user *buf is thus 4 bytes in all cases, as is __u32
> buf.
Ah, yes, that's true. I was hitting this on arm64 builds
(CONFIG_COMPILE_TEST) where __user *buf is 64-bit. So, the "additionally
fixes" bit above is misleading in the sense that nothing was ever built
in the real world like that.
The patch still fixes the compile-time warnings, though.
However, I don't think anything actually uses any of this code
regardless. ;)
-Kees
>
> > I actually think this code is completely unused in the real world:
> > I don't think it could have ever worked, as it would either always
> > fail (with an uninitialized data->buf_size) or would cause corruption
> > in userspace due to the copy_to_user() in the call path against an
> > uninitialized data->buf value:
> >
> > omap3isp_stat_request_statistics_time32(...)
> > struct omap3isp_stat_data data64;
> > ...
> > omap3isp_stat_request_statistics(stat, &data64);
> >
> > int omap3isp_stat_request_statistics(struct ispstat *stat,
> > struct omap3isp_stat_data *data)
> > ...
> > buf = isp_stat_buf_get(stat, data);
> >
> > static struct ispstat_buffer *isp_stat_buf_get(struct ispstat *stat,
> > struct omap3isp_stat_data *data)
> > ...
> > if (buf->buf_size > data->buf_size) {
> > ...
> > return ERR_PTR(-EINVAL);
> > }
> > ...
> > rval = copy_to_user(data->buf,
> > buf->virt_addr,
> > buf->buf_size);
> >
> > Regardless, additionally initialize data64 to be zero-filled to avoid
> > undefined behavior.
> >
> > Fixes: 378e3f81cb56 ("media: omap3isp: support 64-bit version of omap3isp_stat_data")
> > Signed-off-by: Kees Cook <[email protected]>
> > ---
> > drivers/media/platform/omap3isp/ispstat.c | 5 +--
> > include/uapi/linux/omap3isp.h | 44 +++++++++++++++++------
> > 2 files changed, 36 insertions(+), 13 deletions(-)
> >
> > diff --git a/drivers/media/platform/omap3isp/ispstat.c b/drivers/media/platform/omap3isp/ispstat.c
> > index 5b9b57f4d9bf..ea8222fed38e 100644
> > --- a/drivers/media/platform/omap3isp/ispstat.c
> > +++ b/drivers/media/platform/omap3isp/ispstat.c
> > @@ -512,7 +512,7 @@ int omap3isp_stat_request_statistics(struct ispstat *stat,
> > int omap3isp_stat_request_statistics_time32(struct ispstat *stat,
> > struct omap3isp_stat_data_time32 *data)
> > {
> > - struct omap3isp_stat_data data64;
> > + struct omap3isp_stat_data data64 = { };
> > int ret;
> >
> > ret = omap3isp_stat_request_statistics(stat, &data64);
> > @@ -521,7 +521,8 @@ int omap3isp_stat_request_statistics_time32(struct ispstat *stat,
> >
> > data->ts.tv_sec = data64.ts.tv_sec;
> > data->ts.tv_usec = data64.ts.tv_usec;
> > - memcpy(&data->buf, &data64.buf, sizeof(*data) - sizeof(data->ts));
> > + data->buf = (uintptr_t)data64.buf;
> > + memcpy(&data->frame, &data64.buf, sizeof(data->frame));
> >
> > return 0;
> > }
> > diff --git a/include/uapi/linux/omap3isp.h b/include/uapi/linux/omap3isp.h
> > index 87b55755f4ff..0a16af91621f 100644
> > --- a/include/uapi/linux/omap3isp.h
> > +++ b/include/uapi/linux/omap3isp.h
> > @@ -159,13 +159,25 @@ struct omap3isp_h3a_aewb_config {
> > };
> >
> > /**
> > - * struct omap3isp_stat_data - Statistic data sent to or received from user
> > - * @ts: Timestamp of returned framestats.
> > - * @buf: Pointer to pass to user.
> > + * struct omap3isp_stat_frame - Statistic data without timestamp nor pointer.
> > + * @buf_size: Size of buffer.
> > * @frame_number: Frame number of requested stats.
> > * @cur_frame: Current frame number being processed.
> > * @config_counter: Number of the configuration associated with the data.
> > */
> > +struct omap3isp_stat_frame {
> > + __u32 buf_size;
> > + __u16 frame_number;
> > + __u16 cur_frame;
> > + __u16 config_counter;
> > +};
> > +
> > +/**
> > + * struct omap3isp_stat_data - Statistic data sent to or received from user
> > + * @ts: Timestamp of returned framestats.
> > + * @buf: Pointer to pass to user.
> > + * @frame: Statistic data for frame.
> > + */
> > struct omap3isp_stat_data {
> > #ifdef __KERNEL__
> > struct {
> > @@ -176,10 +188,15 @@ struct omap3isp_stat_data {
> > struct timeval ts;
> > #endif
> > void __user *buf;
> > - __u32 buf_size;
> > - __u16 frame_number;
> > - __u16 cur_frame;
> > - __u16 config_counter;
> > + union {
> > + struct {
> > + __u32 buf_size;
> > + __u16 frame_number;
> > + __u16 cur_frame;
> > + __u16 config_counter;
> > + };
> > + struct omap3isp_stat_frame frame;
> > + };
> > };
> >
> > #ifdef __KERNEL__
> > @@ -189,10 +206,15 @@ struct omap3isp_stat_data_time32 {
> > __s32 tv_usec;
> > } ts;
> > __u32 buf;
> > - __u32 buf_size;
> > - __u16 frame_number;
> > - __u16 cur_frame;
> > - __u16 config_counter;
> > + union {
> > + struct {
> > + __u32 buf_size;
> > + __u16 frame_number;
> > + __u16 cur_frame;
> > + __u16 config_counter;
> > + };
> > + struct omap3isp_stat_frame frame;
> > + };
> > };
> > #endif
> >
>
> --
> Regards,
>
> Laurent Pinchart
--
Kees Cook
Hi Kees,
On Wed, Jun 16, 2021 at 09:22:23PM -0700, Kees Cook wrote:
> On Wed, Jun 16, 2021 at 10:43:03PM +0300, Laurent Pinchart wrote:
> > On Wed, Jun 16, 2021 at 11:59:38AM -0700, Kees Cook wrote:
> > > Avoid writing past the end of a structure member by wrapping the target
> > > region in a common named structure. This additionally fixes a
> > > misalignment of the copy (since the size of "buf" changes between 64-bit
> > > and 32-bit).
> >
> > Could you have been mislead by the data64 name ? The difference between
> > omap3isp_stat_data_time and omap3isp_stat_data_time32 is the size of the
> > ts field, using 32-bit timestamps with legacy userspace, and 64-bit
> > timestamps with more recent userspace. In both cases we're dealing with
> > a 32-bit platform, as the omap3isp is not used in any 64-bit ARM SoC.
> > The size of void __user *buf is thus 4 bytes in all cases, as is __u32
> > buf.
>
> Ah, yes, that's true. I was hitting this on arm64 builds
> (CONFIG_COMPILE_TEST) where __user *buf is 64-bit. So, the "additionally
> fixes" bit above is misleading in the sense that nothing was ever built
> in the real world like that.
>
> The patch still fixes the compile-time warnings, though.
I What's the compile-time warning ? I tried compiling the driver for
ARM64 and didn't notice any.
> However, I don't think anything actually uses any of this code
> regardless. ;)
>
> > > I actually think this code is completely unused in the real world:
> > > I don't think it could have ever worked, as it would either always
> > > fail (with an uninitialized data->buf_size) or would cause corruption
> > > in userspace due to the copy_to_user() in the call path against an
> > > uninitialized data->buf value:
> > >
> > > omap3isp_stat_request_statistics_time32(...)
> > > struct omap3isp_stat_data data64;
> > > ...
> > > omap3isp_stat_request_statistics(stat, &data64);
> > >
> > > int omap3isp_stat_request_statistics(struct ispstat *stat,
> > > struct omap3isp_stat_data *data)
> > > ...
> > > buf = isp_stat_buf_get(stat, data);
> > >
> > > static struct ispstat_buffer *isp_stat_buf_get(struct ispstat *stat,
> > > struct omap3isp_stat_data *data)
> > > ...
> > > if (buf->buf_size > data->buf_size) {
> > > ...
> > > return ERR_PTR(-EINVAL);
> > > }
> > > ...
> > > rval = copy_to_user(data->buf,
> > > buf->virt_addr,
> > > buf->buf_size);
> > >
> > > Regardless, additionally initialize data64 to be zero-filled to avoid
> > > undefined behavior.
> > >
> > > Fixes: 378e3f81cb56 ("media: omap3isp: support 64-bit version of omap3isp_stat_data")
> > > Signed-off-by: Kees Cook <[email protected]>
> > > ---
> > > drivers/media/platform/omap3isp/ispstat.c | 5 +--
> > > include/uapi/linux/omap3isp.h | 44 +++++++++++++++++------
> > > 2 files changed, 36 insertions(+), 13 deletions(-)
> > >
> > > diff --git a/drivers/media/platform/omap3isp/ispstat.c b/drivers/media/platform/omap3isp/ispstat.c
> > > index 5b9b57f4d9bf..ea8222fed38e 100644
> > > --- a/drivers/media/platform/omap3isp/ispstat.c
> > > +++ b/drivers/media/platform/omap3isp/ispstat.c
> > > @@ -512,7 +512,7 @@ int omap3isp_stat_request_statistics(struct ispstat *stat,
> > > int omap3isp_stat_request_statistics_time32(struct ispstat *stat,
> > > struct omap3isp_stat_data_time32 *data)
> > > {
> > > - struct omap3isp_stat_data data64;
> > > + struct omap3isp_stat_data data64 = { };
> > > int ret;
> > >
> > > ret = omap3isp_stat_request_statistics(stat, &data64);
> > > @@ -521,7 +521,8 @@ int omap3isp_stat_request_statistics_time32(struct ispstat *stat,
> > >
> > > data->ts.tv_sec = data64.ts.tv_sec;
> > > data->ts.tv_usec = data64.ts.tv_usec;
> > > - memcpy(&data->buf, &data64.buf, sizeof(*data) - sizeof(data->ts));
> > > + data->buf = (uintptr_t)data64.buf;
> > > + memcpy(&data->frame, &data64.buf, sizeof(data->frame));
> > >
> > > return 0;
> > > }
> > > diff --git a/include/uapi/linux/omap3isp.h b/include/uapi/linux/omap3isp.h
> > > index 87b55755f4ff..0a16af91621f 100644
> > > --- a/include/uapi/linux/omap3isp.h
> > > +++ b/include/uapi/linux/omap3isp.h
> > > @@ -159,13 +159,25 @@ struct omap3isp_h3a_aewb_config {
> > > };
> > >
> > > /**
> > > - * struct omap3isp_stat_data - Statistic data sent to or received from user
> > > - * @ts: Timestamp of returned framestats.
> > > - * @buf: Pointer to pass to user.
> > > + * struct omap3isp_stat_frame - Statistic data without timestamp nor pointer.
> > > + * @buf_size: Size of buffer.
> > > * @frame_number: Frame number of requested stats.
> > > * @cur_frame: Current frame number being processed.
> > > * @config_counter: Number of the configuration associated with the data.
> > > */
> > > +struct omap3isp_stat_frame {
> > > + __u32 buf_size;
> > > + __u16 frame_number;
> > > + __u16 cur_frame;
> > > + __u16 config_counter;
> > > +};
> > > +
> > > +/**
> > > + * struct omap3isp_stat_data - Statistic data sent to or received from user
> > > + * @ts: Timestamp of returned framestats.
> > > + * @buf: Pointer to pass to user.
> > > + * @frame: Statistic data for frame.
> > > + */
> > > struct omap3isp_stat_data {
> > > #ifdef __KERNEL__
> > > struct {
> > > @@ -176,10 +188,15 @@ struct omap3isp_stat_data {
> > > struct timeval ts;
> > > #endif
> > > void __user *buf;
> > > - __u32 buf_size;
> > > - __u16 frame_number;
> > > - __u16 cur_frame;
> > > - __u16 config_counter;
> > > + union {
> > > + struct {
> > > + __u32 buf_size;
> > > + __u16 frame_number;
> > > + __u16 cur_frame;
> > > + __u16 config_counter;
> > > + };
> > > + struct omap3isp_stat_frame frame;
> > > + };
> > > };
> > >
> > > #ifdef __KERNEL__
> > > @@ -189,10 +206,15 @@ struct omap3isp_stat_data_time32 {
> > > __s32 tv_usec;
> > > } ts;
> > > __u32 buf;
> > > - __u32 buf_size;
> > > - __u16 frame_number;
> > > - __u16 cur_frame;
> > > - __u16 config_counter;
> > > + union {
> > > + struct {
> > > + __u32 buf_size;
> > > + __u16 frame_number;
> > > + __u16 cur_frame;
> > > + __u16 config_counter;
> > > + };
> > > + struct omap3isp_stat_frame frame;
> > > + };
> > > };
> > > #endif
> > >
--
Regards,
Laurent Pinchart
On Thu, Jun 24, 2021 at 01:12:11AM +0300, Laurent Pinchart wrote:
> Hi Kees,
>
> On Wed, Jun 16, 2021 at 09:22:23PM -0700, Kees Cook wrote:
> > On Wed, Jun 16, 2021 at 10:43:03PM +0300, Laurent Pinchart wrote:
> > > On Wed, Jun 16, 2021 at 11:59:38AM -0700, Kees Cook wrote:
> > > > Avoid writing past the end of a structure member by wrapping the target
> > > > region in a common named structure. This additionally fixes a
> > > > misalignment of the copy (since the size of "buf" changes between 64-bit
> > > > and 32-bit).
> > >
> > > Could you have been mislead by the data64 name ? The difference between
> > > omap3isp_stat_data_time and omap3isp_stat_data_time32 is the size of the
> > > ts field, using 32-bit timestamps with legacy userspace, and 64-bit
> > > timestamps with more recent userspace. In both cases we're dealing with
> > > a 32-bit platform, as the omap3isp is not used in any 64-bit ARM SoC.
> > > The size of void __user *buf is thus 4 bytes in all cases, as is __u32
> > > buf.
> >
> > Ah, yes, that's true. I was hitting this on arm64 builds
> > (CONFIG_COMPILE_TEST) where __user *buf is 64-bit. So, the "additionally
> > fixes" bit above is misleading in the sense that nothing was ever built
> > in the real world like that.
> >
> > The patch still fixes the compile-time warnings, though.
>
> I What's the compile-time warning ? I tried compiling the driver for
> ARM64 and didn't notice any.
Sorry, I didn't include the background well enough in the commit log,
but it's part of a tightening of memcpy() under FORTIFY_SOURCE and
also -Warray-bounds enablement. Here's what I've been saying on other
patches (this one was different because it seemed to be just broken
code):
In preparation for FORTIFY_SOURCE performing compile-time and run-time
field bounds checking for memcpy(), memmove(), and memset(), avoid
intentionally writing across neighboring fields.
Anyway, I can carry this until the full series is posted, but I'm still
working through a few more fixes before I send the whole thing. This
patch was one of a handful that didn't have any series dependencies.
-Kees
--
Kees Cook