From: Andi Kleen ak@linux.intel.com
commit e14fd4ba8fb47fcf5f244366ec01ae94490cd86a upstream.
When a split lock is detected always make sure to disable interrupts before returning from the trap handler.
The kernel exit code assumes that all exits run with interrupts disabled, otherwise the SWAPGS sequence can race against interrupts and cause recursing page faults and later panics.
The problem will only happen on CPUs with split lock disable functionality, so Icelake Server, Tiger Lake, Snow Ridge, Jacobsville.
Fixes: ca4c6a9858c2 ("x86/traps: Make interrupt enable/disable symmetric in C code") Fixes: bce9b042ec73 ("x86/traps: Disable interrupts in exc_aligment_check()") # v5.8+ Signed-off-by: Andi Kleen ak@linux.intel.com Cc: Peter Zijlstra peterz@infradead.org Cc: Fenghua Yu fenghua.yu@intel.com Cc: Tony Luck tony.luck@intel.com Reviewed-by: Thomas Gleixner tglx@linutronix.de Signed-off-by: Linus Torvalds torvalds@linux-foundation.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- arch/x86/kernel/traps.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
--- a/arch/x86/kernel/traps.c +++ b/arch/x86/kernel/traps.c @@ -299,11 +299,12 @@ DEFINE_IDTENTRY_ERRORCODE(exc_alignment_ local_irq_enable();
if (handle_user_split_lock(regs, error_code)) - return; + goto out;
do_trap(X86_TRAP_AC, SIGBUS, "alignment check", regs, error_code, BUS_ADRALN, NULL);
+out: local_irq_disable(); }