| Message ID | 20180827185631.163506-8-jannh@google.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | x86: BUG() on #GP / kernel #PF in uaccess | expand |
On Mon, Aug 27, 2018 at 11:56 AM, Jann Horn <jannh@google.com> wrote: > Test whether the kernel WARN()s when, under KERNEL_DS, a bad kernel pointer > is used as "userspace" pointer. Should normally be used in "DIRECT" mode. > > Signed-off-by: Jann Horn <jannh@google.com> Acked-by: Kees Cook <keescook@chromium.org> -Kees > --- > drivers/misc/lkdtm/core.c | 1 + > drivers/misc/lkdtm/lkdtm.h | 1 + > drivers/misc/lkdtm/usercopy.c | 13 +++++++++++++ > 3 files changed, 15 insertions(+) > > diff --git a/drivers/misc/lkdtm/core.c b/drivers/misc/lkdtm/core.c > index 2154d1bfd18b..5a755590d3dc 100644 > --- a/drivers/misc/lkdtm/core.c > +++ b/drivers/misc/lkdtm/core.c > @@ -183,6 +183,7 @@ static const struct crashtype crashtypes[] = { > CRASHTYPE(USERCOPY_STACK_FRAME_FROM), > CRASHTYPE(USERCOPY_STACK_BEYOND), > CRASHTYPE(USERCOPY_KERNEL), > + CRASHTYPE(USERCOPY_KERNEL_DS), > }; > > > diff --git a/drivers/misc/lkdtm/lkdtm.h b/drivers/misc/lkdtm/lkdtm.h > index 9e513dcfd809..07db641d71d0 100644 > --- a/drivers/misc/lkdtm/lkdtm.h > +++ b/drivers/misc/lkdtm/lkdtm.h > @@ -82,5 +82,6 @@ void lkdtm_USERCOPY_STACK_FRAME_TO(void); > void lkdtm_USERCOPY_STACK_FRAME_FROM(void); > void lkdtm_USERCOPY_STACK_BEYOND(void); > void lkdtm_USERCOPY_KERNEL(void); > +void lkdtm_USERCOPY_KERNEL_DS(void); > > #endif > diff --git a/drivers/misc/lkdtm/usercopy.c b/drivers/misc/lkdtm/usercopy.c > index 9725aed305bb..389475b25bb7 100644 > --- a/drivers/misc/lkdtm/usercopy.c > +++ b/drivers/misc/lkdtm/usercopy.c > @@ -322,6 +322,19 @@ void lkdtm_USERCOPY_KERNEL(void) > vm_munmap(user_addr, PAGE_SIZE); > } > > +void lkdtm_USERCOPY_KERNEL_DS(void) > +{ > + char __user *user_ptr = (char __user *)ERR_PTR(-EINVAL); > + mm_segment_t old_fs = get_fs(); > + char buf[10] = {0}; > + > + pr_info("attempting copy_to_user on unmapped kernel address\n"); > + set_fs(KERNEL_DS); > + if (copy_to_user(user_ptr, buf, sizeof(buf))) > + pr_info("copy_to_user un unmapped kernel address failed\n"); > + set_fs(old_fs); > +} > + > void __init lkdtm_usercopy_init(void) > { > /* Prepare cache that lacks SLAB_USERCOPY flag. */ > -- > 2.19.0.rc0.228.g281dcd1b4d0-goog >
diff --git a/drivers/misc/lkdtm/core.c b/drivers/misc/lkdtm/core.c index 2154d1bfd18b..5a755590d3dc 100644 --- a/drivers/misc/lkdtm/core.c +++ b/drivers/misc/lkdtm/core.c @@ -183,6 +183,7 @@ static const struct crashtype crashtypes[] = { CRASHTYPE(USERCOPY_STACK_FRAME_FROM), CRASHTYPE(USERCOPY_STACK_BEYOND), CRASHTYPE(USERCOPY_KERNEL), + CRASHTYPE(USERCOPY_KERNEL_DS), }; diff --git a/drivers/misc/lkdtm/lkdtm.h b/drivers/misc/lkdtm/lkdtm.h index 9e513dcfd809..07db641d71d0 100644 --- a/drivers/misc/lkdtm/lkdtm.h +++ b/drivers/misc/lkdtm/lkdtm.h @@ -82,5 +82,6 @@ void lkdtm_USERCOPY_STACK_FRAME_TO(void); void lkdtm_USERCOPY_STACK_FRAME_FROM(void); void lkdtm_USERCOPY_STACK_BEYOND(void); void lkdtm_USERCOPY_KERNEL(void); +void lkdtm_USERCOPY_KERNEL_DS(void); #endif diff --git a/drivers/misc/lkdtm/usercopy.c b/drivers/misc/lkdtm/usercopy.c index 9725aed305bb..389475b25bb7 100644 --- a/drivers/misc/lkdtm/usercopy.c +++ b/drivers/misc/lkdtm/usercopy.c @@ -322,6 +322,19 @@ void lkdtm_USERCOPY_KERNEL(void) vm_munmap(user_addr, PAGE_SIZE); } +void lkdtm_USERCOPY_KERNEL_DS(void) +{ + char __user *user_ptr = (char __user *)ERR_PTR(-EINVAL); + mm_segment_t old_fs = get_fs(); + char buf[10] = {0}; + + pr_info("attempting copy_to_user on unmapped kernel address\n"); + set_fs(KERNEL_DS); + if (copy_to_user(user_ptr, buf, sizeof(buf))) + pr_info("copy_to_user un unmapped kernel address failed\n"); + set_fs(old_fs); +} + void __init lkdtm_usercopy_init(void) { /* Prepare cache that lacks SLAB_USERCOPY flag. */
Test whether the kernel WARN()s when, under KERNEL_DS, a bad kernel pointer is used as "userspace" pointer. Should normally be used in "DIRECT" mode. Signed-off-by: Jann Horn <jannh@google.com> --- drivers/misc/lkdtm/core.c | 1 + drivers/misc/lkdtm/lkdtm.h | 1 + drivers/misc/lkdtm/usercopy.c | 13 +++++++++++++ 3 files changed, 15 insertions(+)