On Mon, Jul 27, 2020 at 09:25:16AM +0200, Arnd Bergmann wrote: > On Mon, Jul 27, 2020 at 12:28 AM Peilin Ye <yepeilin.cs@xxxxxxxxx> wrote: > > > > video_put_user() is copying uninitialized stack memory to userspace due > > to the compiler not initializing holes in the structures declared on the > > stack. Fix it by initializing `ev32` and `vb32` using memset(). > > > > Reported-and-tested-by: syzbot+79d751604cb6f29fbf59@xxxxxxxxxxxxxxxxxxxxxxxxx > > Link: https://syzkaller.appspot.com/bug?extid=79d751604cb6f29fbf59 > > Reviewed-by: Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx> > > Signed-off-by: Peilin Ye <yepeilin.cs@xxxxxxxxx> > > Thanks a lot for addressing this! I now see that I actually created a similar > bugfix for it back in January, but for some reason that got stuck in my > backlog and I never wrote a proper description for it or sent it out to the > list, sorry about that. I would hope we could find a way to have either > the compiler or sparse warn if we copy uninitialized data to user space, > but we now don't even check for that within the kernel any more. Here are my latest warnings on linux-next from Friday. block/scsi_ioctl.c:707 scsi_put_cdrom_generic_arg() warn: check that 'cgc32' doesn't leak information (struct has a hole after 'data_direction') drivers/input/misc/uinput.c:743 uinput_ff_upload_to_user() warn: check that 'ff_up_compat' doesn't leak information (struct has a hole after 'replay') drivers/input/misc/uinput.c:958 uinput_ioctl_handler() warn: check that 'ff_up' doesn't leak information (struct has a hole after 'replay') drivers/firewire/core-cdev.c:463 ioctl_get_info() warn: check that 'bus_reset' doesn't leak information (struct has a hole after 'generation') drivers/scsi/megaraid/megaraid_mm.c:824 kioc_to_mimd() warn: check that 'cinfo.base' doesn't leak information drivers/gpio/gpiolib-cdev.c:473 lineevent_read() warn: check that 'ge' doesn't leak information (struct has a hole after 'id') drivers/gpu/drm/i915/i915_query.c:136 query_engine_info() warn: check that 'query.num_engines' doesn't leak information drivers/gpu/drm/drm_bufs.c:1357 copy_one_buf() warn: check that 'v' doesn't leak information (struct has a hole after 'flags') drivers/gpu/drm/amd/amdgpu/amdgpu_kms.c:785 amdgpu_info_ioctl() warn: check that 'dev_info' doesn't leak information (struct has a hole after 'pa_sc_tile_steering_override') drivers/block/floppy.c:3132 raw_cmd_copyout() warn: check that 'cmd' doesn't leak information (struct has a hole after 'flags') drivers/char/hpet.c:675 hpet_ioctl() warn: check that 'info' doesn't leak information (struct has a hole after 'hi_timer') drivers/media/v4l2-core/v4l2-ioctl.c:3204 video_put_user() warn: check that 'ev32' doesn't leak information (struct has a hole after 'type') drivers/media/v4l2-core/v4l2-ioctl.c:3229 video_put_user() warn: check that 'vb32' doesn't leak information (struct has a hole after 'memory') drivers/net/wan/sbni.c:1320 sbni_ioctl() warn: check that 'flags' doesn't leak information (struct has a hole after 'rxl') drivers/infiniband/hw/qedr/verbs.c:1816 qedr_create_user_qp() warn: check that 'uresp' doesn't leak information (struct has a hole after 'sq_icid') drivers/infiniband/hw/cxgb4/provider.c:107 c4iw_alloc_ucontext() warn: check that 'uresp.reserved' doesn't leak information drivers/tty/vt/vt_ioctl.c:1218 vt_compat_ioctl() warn: check that 'op' doesn't leak information (struct has a hole after 'charcount') net/smc/smc_diag.c:181 __smc_diag_dump() warn: check that 'dinfo' doesn't leak information (struct has a hole after 'linkid') net/sched/act_ife.c:638 tcf_ife_dump() warn: check that 'opt' doesn't leak information (struct has a hole after 'flags') net/sched/act_skbmod.c:232 tcf_skbmod_dump() warn: check that 'opt' doesn't leak information (struct has a hole after 'bindcnt') net/sched/act_connmark.c:187 tcf_connmark_dump() warn: check that 'opt' doesn't leak information (struct has a hole after 'zone') net/openvswitch/conntrack.c:311 ovs_ct_put_key() warn: check that 'orig' doesn't leak information (struct has a hole after 'ipv4_proto') net/openvswitch/conntrack.c:322 ovs_ct_put_key() warn: check that 'orig' doesn't leak information (struct has a hole after 'ipv6_proto') net/rds/recv.c:492 rds_notify_queue_get() warn: check that 'cmsg' doesn't leak information (struct has a hole after 'status') net/xdp/xsk.c:870 xsk_getsockopt() warn: check that 'stats.rx_ring_full' doesn't leak information kernel/signal.c:3524 __do_sys_rt_sigtimedwait() warn: check that 'info' doesn't leak information (struct has a hole after 'si_code') kernel/signal.c:3524 __do_sys_rt_sigtimedwait() warn: check that 'info' doesn't leak information (struct has a hole after 'si_code') kernel/signal.c:3556 __do_sys_rt_sigtimedwait_time32() warn: check that 'info' doesn't leak information (struct has a hole after 'si_code') kernel/signal.c:3556 __do_sys_rt_sigtimedwait_time32() warn: check that 'info' doesn't leak information (struct has a hole after 'si_code') kernel/signal.c:4055 __do_sys_sigaltstack() warn: check that 'old' doesn't leak information (struct has a hole after 'ss_flags') kernel/signal.c:4055 __do_sys_sigaltstack() warn: check that 'old' doesn't leak information (struct has a hole after 'ss_flags') kernel/ptrace.c:998 ptrace_get_syscall_info() warn: check that 'info' doesn't leak information (struct has a hole after 'op') regards, dan carpenter
