From: Sami Tolvanen samitolvanen@google.com
commit 57cd6d157eb479f0a8e820fd36b7240845c8a937 upstream.
RCU_NONIDLE usage during __cfi_slowpath_diag can result in an invalid RCU state in the cpuidle code path:
WARNING: CPU: 1 PID: 0 at kernel/rcu/tree.c:613 rcu_eqs_enter+0xe4/0x138 ... Call trace: rcu_eqs_enter+0xe4/0x138 rcu_idle_enter+0xa8/0x100 cpuidle_enter_state+0x154/0x3a8 cpuidle_enter+0x3c/0x58 do_idle.llvm.6590768638138871020+0x1f4/0x2ec cpu_startup_entry+0x28/0x2c secondary_start_kernel+0x1b8/0x220 __secondary_switched+0x94/0x98
Instead, call rcu_irq_enter/exit to wake up RCU only when needed and disable interrupts for the entire CFI shadow/module check when we do.
Signed-off-by: Sami Tolvanen samitolvanen@google.com Link: https://lore.kernel.org/r/20220531175910.890307-1-samitolvanen@google.com Fixes: cf68fffb66d6 ("add support for Clang CFI") Cc: stable@vger.kernel.org Signed-off-by: Kees Cook keescook@chromium.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- kernel/cfi.c | 22 ++++++++++++++++------ 1 file changed, 16 insertions(+), 6 deletions(-)
--- a/kernel/cfi.c +++ b/kernel/cfi.c @@ -281,6 +281,8 @@ static inline cfi_check_fn find_module_c static inline cfi_check_fn find_check_fn(unsigned long ptr) { cfi_check_fn fn = NULL; + unsigned long flags; + bool rcu_idle;
if (is_kernel_text(ptr)) return __cfi_check; @@ -290,13 +292,21 @@ static inline cfi_check_fn find_check_fn * the shadow and __module_address use RCU, so we need to wake it * up if necessary. */ - RCU_NONIDLE({ - if (IS_ENABLED(CONFIG_CFI_CLANG_SHADOW)) - fn = find_shadow_check_fn(ptr); + rcu_idle = !rcu_is_watching(); + if (rcu_idle) { + local_irq_save(flags); + rcu_irq_enter(); + }
- if (!fn) - fn = find_module_check_fn(ptr); - }); + if (IS_ENABLED(CONFIG_CFI_CLANG_SHADOW)) + fn = find_shadow_check_fn(ptr); + if (!fn) + fn = find_module_check_fn(ptr); + + if (rcu_idle) { + rcu_irq_exit(); + local_irq_restore(flags); + }
return fn; }