From e14fd4ba8fb47fcf5f244366ec01ae94490cd86a Mon Sep 17 00:00:00 2001 From: Andi Kleen Date: Tue, 22 Dec 2020 09:40:10 -0800 Subject: [PATCH] x86/split-lock: Avoid returning with interrupts enabled 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 Cc: Peter Zijlstra Cc: Fenghua Yu Cc: Tony Luck Reviewed-by: Thomas Gleixner Signed-off-by: Linus Torvalds --- arch/x86/kernel/traps.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c index fb55981f2a0d0..7f5aec758f0ee 100644 --- a/arch/x86/kernel/traps.c +++ b/arch/x86/kernel/traps.c @@ -303,11 +303,12 @@ DEFINE_IDTENTRY_ERRORCODE(exc_alignment_check) 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(); } -- 2.39.5