| Message ID | 1488827386-87193-6-git-send-email-keescook@chromium.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Mon, Mar 6, 2017 at 11:09 AM, Kees Cook <keescook@chromium.org> wrote: > When performing notifier function pointer sanity checking, allow > CONFIG_BUG_ON_DATA_CORRUPTION to upgrade from a WARN to a BUG. > Additionally enables CONFIG_DEBUG_NOTIFIERS when selecting > CONFIG_BUG_ON_DATA_CORRUPTION. Any feedback on this change? By default, this retains the existing WARN behavior... -Kees > > Signed-off-by: Kees Cook <keescook@chromium.org> > --- > kernel/notifier.c | 5 +++-- > lib/Kconfig.debug | 3 ++- > 2 files changed, 5 insertions(+), 3 deletions(-) > > diff --git a/kernel/notifier.c b/kernel/notifier.c > index 6196af8a8223..58cc14958d92 100644 > --- a/kernel/notifier.c > +++ b/kernel/notifier.c > @@ -84,8 +84,9 @@ static int notifier_call_chain(struct notifier_block **nl, > next_nb = rcu_dereference_raw(nb->next); > > #ifdef CONFIG_DEBUG_NOTIFIERS > - if (unlikely(!func_ptr_is_kernel_text(nb->notifier_call))) { > - WARN(1, "Invalid notifier called!"); > + if (CHECK_DATA_CORRUPTION( > + !func_ptr_is_kernel_text(nb->notifier_call), > + "Invalid notifier called!")) { > nb = next_nb; > continue; > } > diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug > index 42c61cfe7d19..70e9f2c1bb30 100644 > --- a/lib/Kconfig.debug > +++ b/lib/Kconfig.debug > @@ -1277,7 +1277,7 @@ config DEBUG_SG > > config DEBUG_NOTIFIERS > bool "Debug notifier call chains" > - depends on DEBUG_KERNEL > + depends on DEBUG_KERNEL || BUG_ON_DATA_CORRUPTION > help > Enable this to turn on sanity checking for notifier call chains. > This is most useful for kernel developers to make sure that > @@ -1995,6 +1995,7 @@ config BUG_ON_DATA_CORRUPTION > bool "Trigger a BUG when data corruption is detected" > select DEBUG_CREDENTIALS > select DEBUG_LIST > + select DEBUG_NOTIFIERS > select DEBUG_SG > help > This option enables several inexpensive data corruption checks. > -- > 2.7.4 >
On 3/22/2017 12:29 PM, Kees Cook wrote: >> When performing notifier function pointer sanity checking, allow >> CONFIG_BUG_ON_DATA_CORRUPTION to upgrade from a WARN to a BUG. >> Additionally enables CONFIG_DEBUG_NOTIFIERS when selecting >> CONFIG_BUG_ON_DATA_CORRUPTION. > Any feedback on this change? By default, this retains the existing > WARN behavior... if you're upgrading, is the end point really a panic() ? e.g. do you assume people to also set panic-on-oops?
On Wed, Mar 22, 2017 at 12:32 PM, Arjan van de Ven <arjan@linux.intel.com> wrote: > On 3/22/2017 12:29 PM, Kees Cook wrote: >>> >>> When performing notifier function pointer sanity checking, allow >>> CONFIG_BUG_ON_DATA_CORRUPTION to upgrade from a WARN to a BUG. >>> Additionally enables CONFIG_DEBUG_NOTIFIERS when selecting >>> CONFIG_BUG_ON_DATA_CORRUPTION. > > >> Any feedback on this change? By default, this retains the existing >> WARN behavior... > > > if you're upgrading, is the end point really a panic() ? > e.g. do you assume people to also set panic-on-oops? That's one option, yes. With the BUG, the process associated is killed (which is the first level of defense upgrade), and if a system is also set to panic-on-oops, the entire system will panic (and usually such systems also retain their crash consoles in some fashion for later analysis, etc). -Kees
diff --git a/kernel/notifier.c b/kernel/notifier.c index 6196af8a8223..58cc14958d92 100644 --- a/kernel/notifier.c +++ b/kernel/notifier.c @@ -84,8 +84,9 @@ static int notifier_call_chain(struct notifier_block **nl, next_nb = rcu_dereference_raw(nb->next); #ifdef CONFIG_DEBUG_NOTIFIERS - if (unlikely(!func_ptr_is_kernel_text(nb->notifier_call))) { - WARN(1, "Invalid notifier called!"); + if (CHECK_DATA_CORRUPTION( + !func_ptr_is_kernel_text(nb->notifier_call), + "Invalid notifier called!")) { nb = next_nb; continue; } diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug index 42c61cfe7d19..70e9f2c1bb30 100644 --- a/lib/Kconfig.debug +++ b/lib/Kconfig.debug @@ -1277,7 +1277,7 @@ config DEBUG_SG config DEBUG_NOTIFIERS bool "Debug notifier call chains" - depends on DEBUG_KERNEL + depends on DEBUG_KERNEL || BUG_ON_DATA_CORRUPTION help Enable this to turn on sanity checking for notifier call chains. This is most useful for kernel developers to make sure that @@ -1995,6 +1995,7 @@ config BUG_ON_DATA_CORRUPTION bool "Trigger a BUG when data corruption is detected" select DEBUG_CREDENTIALS select DEBUG_LIST + select DEBUG_NOTIFIERS select DEBUG_SG help This option enables several inexpensive data corruption checks.
When performing notifier function pointer sanity checking, allow CONFIG_BUG_ON_DATA_CORRUPTION to upgrade from a WARN to a BUG. Additionally enables CONFIG_DEBUG_NOTIFIERS when selecting CONFIG_BUG_ON_DATA_CORRUPTION. Signed-off-by: Kees Cook <keescook@chromium.org> --- kernel/notifier.c | 5 +++-- lib/Kconfig.debug | 3 ++- 2 files changed, 5 insertions(+), 3 deletions(-)