| Message ID | 20210616185938.1225218-1-keescook@chromium.org |
|---|---|
| State | New |
| Headers | show |
| Series | media: omap3isp: Extract struct group for memcpy() region | expand |
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 <keescook@chromium.org> > > --- > > 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 <keescook@chromium.org> > > > --- > > > 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
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
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). 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 <keescook@chromium.org> --- drivers/media/platform/omap3isp/ispstat.c | 5 +-- include/uapi/linux/omap3isp.h | 44 +++++++++++++++++------ 2 files changed, 36 insertions(+), 13 deletions(-)