Re: [PATCH 1/2] media: v4l2-core: ignore native time32 ioctls on 64-bit
On 21/03/2021 09:50, Hans Verkuil wrote: > Hi Arnd, >> diff --git a/drivers/media/v4l2-core/v4l2-subdev.c >> b/drivers/media/v4l2-core/v4l2-subdev.c >> index 336133dbc759..9f5573d3b857 100644 >> --- a/drivers/media/v4l2-core/v4l2-subdev.c >> +++ b/drivers/media/v4l2-core/v4l2-subdev.c >> @@ -428,7 +428,7 @@ static long subdev_do_ioctl(struct file *file, unsigned >> int cmd, void *arg) >> >> return v4l2_event_dequeue(vfh, arg, file->f_flags & O_NONBLOCK); >> >> -#ifdef CONFIG_COMPAT_32BIT_TIME >> +#if !defined(CONFIG_64BIT) && defined(CONFIG_COMPAT_32BIT_TIME) >> case VIDIOC_DQEVENT_TIME32: { >> struct v4l2_event_time32 *ev32 = arg; >> struct v4l2_event ev = { }; >> > > This chunk doesn't apply since there is no '#ifdef CONFIG_COMPAT_32BIT_TIME' > in > either the mainline kernel or the media_tree master branch. > > Are we missing a patch for v4l2-subdev.c? Ping! Hans > > Regards, > > Hans >
Re: [PATCH 1/2] media: v4l2-core: ignore native time32 ioctls on 64-bit
Hi Arnd, Thank you for the patch. On Thu, Mar 18, 2021 at 02:43:18PM +0100, Arnd Bergmann wrote: > From: Arnd Bergmann > > Syzbot found that passing ioctl command 0xc0505609 into a 64-bit > kernel from a 32-bit process causes uninitialized kernel memory to > get passed to drivers instead of the user space data: > > BUG: KMSAN: uninit-value in check_array_args > drivers/media/v4l2-core/v4l2-ioctl.c:3041 [inline] > BUG: KMSAN: uninit-value in video_usercopy+0x1631/0x3d30 > drivers/media/v4l2-core/v4l2-ioctl.c:3315 > CPU: 0 PID: 19595 Comm: syz-executor.4 Not tainted 5.11.0-rc7-syzkaller #0 > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS > Google 01/01/2011 > Call Trace: > __dump_stack lib/dump_stack.c:79 [inline] > dump_stack+0x21c/0x280 lib/dump_stack.c:120 > kmsan_report+0xfb/0x1e0 mm/kmsan/kmsan_report.c:118 > __msan_warning+0x5f/0xa0 mm/kmsan/kmsan_instr.c:197 > check_array_args drivers/media/v4l2-core/v4l2-ioctl.c:3041 [inline] > video_usercopy+0x1631/0x3d30 drivers/media/v4l2-core/v4l2-ioctl.c:3315 > video_ioctl2+0x9f/0xb0 drivers/media/v4l2-core/v4l2-ioctl.c:3391 > v4l2_ioctl+0x255/0x290 drivers/media/v4l2-core/v4l2-dev.c:360 > v4l2_compat_ioctl32+0x2c6/0x370 > drivers/media/v4l2-core/v4l2-compat-ioctl32.c:1248 > __do_compat_sys_ioctl fs/ioctl.c:842 [inline] > __se_compat_sys_ioctl+0x53d/0x1100 fs/ioctl.c:793 > __ia32_compat_sys_ioctl+0x4a/0x70 fs/ioctl.c:793 > do_syscall_32_irqs_on arch/x86/entry/common.c:79 [inline] > __do_fast_syscall_32+0x102/0x160 arch/x86/entry/common.c:141 > do_fast_syscall_32+0x6a/0xc0 arch/x86/entry/common.c:166 > do_SYSENTER_32+0x73/0x90 arch/x86/entry/common.c:209 > entry_SYSENTER_compat_after_hwframe+0x4d/0x5c > > The time32 commands are defined but were never meant to be called on > 64-bit machines, as those have always used time64 interfaces. I missed > this in my patch that introduced the time64 handling on 32-bit platforms. > > The problem in this case is the mismatch of one function checking for > the numeric value of the command and another function checking for the > type of process (native vs compat) instead, with the result being that > for this combination, nothing gets copied into the buffer at all. > > Avoid this by only trying to convert the time32 commands when running > on a 32-bit kernel where these are defined in a meaningful way. > > Fixes: 577c89b0ce72 ("media: v4l2-core: fix v4l2_buffer handling for time64 > ABI") > Reported-by: syzbot+142888ffec98ab194...@syzkaller.appspotmail.com > Tested-by: Hans Verkuil > Signed-off-by: Arnd Bergmann v4l2_event vs. v4l2_event32 vs. v4l2_event_time32 vs. v4l2_event32_time32 is a bit confusing. Do I understand correctly that the code below runs for the non-compat path, thus native userspace (32-bit on 32-bit machines, 64-bit on 64-bit machines), and handles the case of a native userspace using a 32-bit time ? If so it indeed doesn't make sense for 64-bit machines. Reviewed-by: Laurent Pinchart > --- > This patch adds two more changes than the version that Hans tested > --- > drivers/media/v4l2-core/v4l2-ioctl.c | 6 +++--- > drivers/media/v4l2-core/v4l2-subdev.c | 2 +- > 2 files changed, 4 insertions(+), 4 deletions(-) > > diff --git a/drivers/media/v4l2-core/v4l2-ioctl.c > b/drivers/media/v4l2-core/v4l2-ioctl.c > index 31d1342e61e8..2b1bb68dc27f 100644 > --- a/drivers/media/v4l2-core/v4l2-ioctl.c > +++ b/drivers/media/v4l2-core/v4l2-ioctl.c > @@ -3115,7 +3115,7 @@ static int check_array_args(unsigned int cmd, void > *parg, size_t *array_size, > static unsigned int video_translate_cmd(unsigned int cmd) > { > switch (cmd) { > -#ifdef CONFIG_COMPAT_32BIT_TIME > +#if !defined(CONFIG_64BIT) && defined(CONFIG_COMPAT_32BIT_TIME) > case VIDIOC_DQEVENT_TIME32: > return VIDIOC_DQEVENT; > case VIDIOC_QUERYBUF_TIME32: > @@ -3169,7 +3169,7 @@ static int video_get_user(void __user *arg, void *parg, > err = v4l2_compat_get_user(arg, parg, cmd); > } else { > switch (cmd) { > -#ifdef CONFIG_COMPAT_32BIT_TIME > +#if !defined(CONFIG_64BIT) && defined(CONFIG_COMPAT_32BIT_TIME) > case VIDIOC_QUERYBUF_TIME32: > case VIDIOC_QBUF_TIME32: > case VIDIOC_DQBUF_TIME32: > @@ -3224,7 +3224,7 @@ static int video_put_user(void __user *arg, void *parg, > return v4l2_compat_put_user(arg, parg, cmd); > > switch (cmd) { > -#ifdef CONFIG_COMPAT_32BIT_TIME > +#if !defined(CONFIG_64BIT) && defined(CONFIG_COMPAT_32BIT_TIME) > case VIDIOC_DQEVENT_TIME32: { > struct v4l2_event *ev = parg; > struct v4l2_event_time32 ev32; > diff --git a/drivers/media/v4l2-core/v4l2-subdev.c > b/drivers/media/v4l2-core/v4l2-subdev.c > index 336133dbc759..9f5573d3b857 100644 > --- a/drivers/media/v4l2-core/v4l2-subdev.c > +++ b/drivers/media/v4l2-core/v4l2-subdev.c > @@ -428,7 +428,7 @@ static long subdev_do_ioctl(struct file *file, unsigned >
Re: [PATCH 1/2] media: v4l2-core: ignore native time32 ioctls on 64-bit
On Thu, Mar 18, 2021 at 4:00 PM Laurent Pinchart wrote: > On Thu, Mar 18, 2021 at 02:43:18PM +0100, Arnd Bergmann wrote: > > v4l2_event vs. v4l2_event32 vs. v4l2_event_time32 vs. > v4l2_event32_time32 is a bit confusing. Do I understand correctly that > the code below runs for the non-compat path, thus native userspace > (32-bit on 32-bit machines, 64-bit on 64-bit machines), and handles the > case of a native userspace using a 32-bit time ? If so it indeed doesn't > make sense for 64-bit machines. Yes, that's correct. The way the structures are defined, we have all four combinations of native/compat pointer and time64/time32 timestamps, but the combination of native pointer with time32 stamps only makes sense for 32-bit users. > Reviewed-by: Laurent Pinchart Thanks, Arnd
Re: [PATCH 1/2] media: v4l2-core: ignore native time32 ioctls on 64-bit
Hi Arnd, On 18/03/2021 14:43, Arnd Bergmann wrote: > From: Arnd Bergmann > > Syzbot found that passing ioctl command 0xc0505609 into a 64-bit > kernel from a 32-bit process causes uninitialized kernel memory to > get passed to drivers instead of the user space data: > > BUG: KMSAN: uninit-value in check_array_args > drivers/media/v4l2-core/v4l2-ioctl.c:3041 [inline] > BUG: KMSAN: uninit-value in video_usercopy+0x1631/0x3d30 > drivers/media/v4l2-core/v4l2-ioctl.c:3315 > CPU: 0 PID: 19595 Comm: syz-executor.4 Not tainted 5.11.0-rc7-syzkaller #0 > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS > Google 01/01/2011 > Call Trace: > __dump_stack lib/dump_stack.c:79 [inline] > dump_stack+0x21c/0x280 lib/dump_stack.c:120 > kmsan_report+0xfb/0x1e0 mm/kmsan/kmsan_report.c:118 > __msan_warning+0x5f/0xa0 mm/kmsan/kmsan_instr.c:197 > check_array_args drivers/media/v4l2-core/v4l2-ioctl.c:3041 [inline] > video_usercopy+0x1631/0x3d30 drivers/media/v4l2-core/v4l2-ioctl.c:3315 > video_ioctl2+0x9f/0xb0 drivers/media/v4l2-core/v4l2-ioctl.c:3391 > v4l2_ioctl+0x255/0x290 drivers/media/v4l2-core/v4l2-dev.c:360 > v4l2_compat_ioctl32+0x2c6/0x370 > drivers/media/v4l2-core/v4l2-compat-ioctl32.c:1248 > __do_compat_sys_ioctl fs/ioctl.c:842 [inline] > __se_compat_sys_ioctl+0x53d/0x1100 fs/ioctl.c:793 > __ia32_compat_sys_ioctl+0x4a/0x70 fs/ioctl.c:793 > do_syscall_32_irqs_on arch/x86/entry/common.c:79 [inline] > __do_fast_syscall_32+0x102/0x160 arch/x86/entry/common.c:141 > do_fast_syscall_32+0x6a/0xc0 arch/x86/entry/common.c:166 > do_SYSENTER_32+0x73/0x90 arch/x86/entry/common.c:209 > entry_SYSENTER_compat_after_hwframe+0x4d/0x5c > > The time32 commands are defined but were never meant to be called on > 64-bit machines, as those have always used time64 interfaces. I missed > this in my patch that introduced the time64 handling on 32-bit platforms. > > The problem in this case is the mismatch of one function checking for > the numeric value of the command and another function checking for the > type of process (native vs compat) instead, with the result being that > for this combination, nothing gets copied into the buffer at all. > > Avoid this by only trying to convert the time32 commands when running > on a 32-bit kernel where these are defined in a meaningful way. > > Fixes: 577c89b0ce72 ("media: v4l2-core: fix v4l2_buffer handling for time64 > ABI") > Reported-by: syzbot+142888ffec98ab194...@syzkaller.appspotmail.com > Tested-by: Hans Verkuil > Signed-off-by: Arnd Bergmann > --- > This patch adds two more changes than the version that Hans tested > --- > drivers/media/v4l2-core/v4l2-ioctl.c | 6 +++--- > drivers/media/v4l2-core/v4l2-subdev.c | 2 +- > 2 files changed, 4 insertions(+), 4 deletions(-) > > diff --git a/drivers/media/v4l2-core/v4l2-ioctl.c > b/drivers/media/v4l2-core/v4l2-ioctl.c > index 31d1342e61e8..2b1bb68dc27f 100644 > --- a/drivers/media/v4l2-core/v4l2-ioctl.c > +++ b/drivers/media/v4l2-core/v4l2-ioctl.c > @@ -3115,7 +3115,7 @@ static int check_array_args(unsigned int cmd, void > *parg, size_t *array_size, > static unsigned int video_translate_cmd(unsigned int cmd) > { > switch (cmd) { > -#ifdef CONFIG_COMPAT_32BIT_TIME > +#if !defined(CONFIG_64BIT) && defined(CONFIG_COMPAT_32BIT_TIME) > case VIDIOC_DQEVENT_TIME32: > return VIDIOC_DQEVENT; > case VIDIOC_QUERYBUF_TIME32: > @@ -3169,7 +3169,7 @@ static int video_get_user(void __user *arg, void *parg, > err = v4l2_compat_get_user(arg, parg, cmd); > } else { > switch (cmd) { > -#ifdef CONFIG_COMPAT_32BIT_TIME > +#if !defined(CONFIG_64BIT) && defined(CONFIG_COMPAT_32BIT_TIME) > case VIDIOC_QUERYBUF_TIME32: > case VIDIOC_QBUF_TIME32: > case VIDIOC_DQBUF_TIME32: > @@ -3224,7 +3224,7 @@ static int video_put_user(void __user *arg, void *parg, > return v4l2_compat_put_user(arg, parg, cmd); > > switch (cmd) { > -#ifdef CONFIG_COMPAT_32BIT_TIME > +#if !defined(CONFIG_64BIT) && defined(CONFIG_COMPAT_32BIT_TIME) > case VIDIOC_DQEVENT_TIME32: { > struct v4l2_event *ev = parg; > struct v4l2_event_time32 ev32; > diff --git a/drivers/media/v4l2-core/v4l2-subdev.c > b/drivers/media/v4l2-core/v4l2-subdev.c > index 336133dbc759..9f5573d3b857 100644 > --- a/drivers/media/v4l2-core/v4l2-subdev.c > +++ b/drivers/media/v4l2-core/v4l2-subdev.c > @@ -428,7 +428,7 @@ static long subdev_do_ioctl(struct file *file, unsigned > int cmd, void *arg) > > return v4l2_event_dequeue(vfh, arg, file->f_flags & O_NONBLOCK); > > -#ifdef CONFIG_COMPAT_32BIT_TIME > +#if !defined(CONFIG_64BIT) && defined(CONFIG_COMPAT_32BIT_TIME) > case VIDIOC_DQEVENT_TIME32: { > struct v4l2_event_time32 *ev32 = arg; > struct v4l2_event ev = { }; > This chunk doesn't apply since there is no '#ifdef CONFIG_COMPAT_32BIT_TIME' in either the mainline