From 2d36d3b451a94899db9c965adde15492ffe6027a Mon Sep 17 00:00:00 2001 From: Li RongQing Date: Mon, 15 Jun 2026 15:01:15 +0800 Subject: [PATCH] x86/ioperm: Prevent NULL dereference on theoretical missing IO bitmap Outside the IOPL emulation path, the IO bitmap is always expected to be allocated when TIF_IO_BITMAP is set. The paranoid WARN_ON_ONCE() handles the case where the flag and the pointer got out of sync. In this theoretical scenario, which presumes some other bug in the code that triggers the WARN_ON_ONCe(), return early, instead of continuing and dereferencing a NULL pointer. [ mingo: Clarified the changelog. ] Signed-off-by: Li RongQing Signed-off-by: Ingo Molnar Reviewed-by: Sohil Mehta Cc: H. Peter Anvin Link: https://patch.msgid.link/20260615070115.4720-1-lirongqing@baidu.com --- arch/x86/kernel/process.c | 1 + 1 file changed, 1 insertion(+) diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c index 4c718f8adc59..d5cd2177f18a 100644 --- a/arch/x86/kernel/process.c +++ b/arch/x86/kernel/process.c @@ -486,6 +486,7 @@ void native_tss_update_io_bitmap(void) if (WARN_ON_ONCE(!iobm)) { clear_thread_flag(TIF_IO_BITMAP); native_tss_invalidate_io_bitmap(); + return; } /*