| Message ID | 20210614103409.3154127-2-arnd@kernel.org |
|---|---|
| State | New |
| Headers | show |
| Series | media: v4l2: compat ioctl fixes | expand |
On Mon, Jun 14, 2021 at 12:34:02PM +0200, Arnd Bergmann wrote: > From: Arnd Bergmann <arnd@arndb.de> > > 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 Can we, please, get a habit to reduce tracebacks to only significant lines? This is not only reduces the storage foot print of repositories in the world (and thus electricity consumed for any operation on it) but also increases density of useful information on one (small, due to reading on laptops / small screen size devices) page. > 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. -- With Best Regards, Andy Shevchenko
Hi Arnd, Thank you for the patch. On Mon, Jun 14, 2021 at 12:34:02PM +0200, Arnd Bergmann wrote: > From: Arnd Bergmann <arnd@arndb.de> > > 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+142888ffec98ab194028@syzkaller.appspotmail.com > Tested-by: Hans Verkuil <hverkuil-cisco@xs4all.nl> > Signed-off-by: Arnd Bergmann <arnd@arndb.de> > --- > This patch adds two more changes than the version that Hans tested > Signed-off-by: Arnd Bergmann <arnd@arndb.de> Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com> > --- > drivers/media/v4l2-core/v4l2-ioctl.c | 6 +++--- > 1 file changed, 3 insertions(+), 3 deletions(-) > > diff --git a/drivers/media/v4l2-core/v4l2-ioctl.c b/drivers/media/v4l2-core/v4l2-ioctl.c > index 2673f51aafa4..58df927aec7e 100644 > --- a/drivers/media/v4l2-core/v4l2-ioctl.c > +++ b/drivers/media/v4l2-core/v4l2-ioctl.c > @@ -3073,7 +3073,7 @@ 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: > @@ -3127,7 +3127,7 @@ 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: > @@ -3182,7 +3182,7 @@ 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; -- Regards, Laurent Pinchart
diff --git a/drivers/media/v4l2-core/v4l2-ioctl.c b/drivers/media/v4l2-core/v4l2-ioctl.c index 2673f51aafa4..58df927aec7e 100644 --- a/drivers/media/v4l2-core/v4l2-ioctl.c +++ b/drivers/media/v4l2-core/v4l2-ioctl.c @@ -3073,7 +3073,7 @@ 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: @@ -3127,7 +3127,7 @@ 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: @@ -3182,7 +3182,7 @@ 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;