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authorSami Tolvanen <samitolvanen@google.com>2022-05-31 10:59:10 -0700
committerKees Cook <keescook@chromium.org>2022-06-13 09:18:46 -0700
commit57cd6d157eb479f0a8e820fd36b7240845c8a937 (patch)
treee19640e7508fe88f5ce7011fefa58a5d91025b6b /kernel
parentb13baccc3850ca8b8cccbf8ed9912dbaa0fdf7f3 (diff)
cfi: Fix __cfi_slowpath_diag RCU usage with cpuidle
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>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/cfi.c22
1 files changed, 16 insertions, 6 deletions
diff --git a/kernel/cfi.c b/kernel/cfi.c
index 9594cfd1cf2c..08102d19ec15 100644
--- a/kernel/cfi.c
+++ b/kernel/cfi.c
@@ -281,6 +281,8 @@ static inline cfi_check_fn find_module_check_fn(unsigned long ptr)
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(unsigned long ptr)
* 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 (IS_ENABLED(CONFIG_CFI_CLANG_SHADOW))
+ fn = find_shadow_check_fn(ptr);
+ if (!fn)
+ fn = find_module_check_fn(ptr);
- if (!fn)
- fn = find_module_check_fn(ptr);
- });
+ if (rcu_idle) {
+ rcu_irq_exit();
+ local_irq_restore(flags);
+ }
return fn;
}