diff options
| -rw-r--r-- | arch/x86/events/core.c | 9 | ||||
| -rw-r--r-- | arch/x86/lib/insn-eval.c | 13 |
2 files changed, 18 insertions, 4 deletions
diff --git a/arch/x86/events/core.c b/arch/x86/events/core.c index 6866cc5acb0b..95118b52b606 100644 --- a/arch/x86/events/core.c +++ b/arch/x86/events/core.c @@ -2803,8 +2803,15 @@ static unsigned long get_segment_base(unsigned int segment) #ifdef CONFIG_MODIFY_LDT_SYSCALL struct ldt_struct *ldt; + /* + * If we're not in a valid context with a real (not just lazy) + * user mm, then don't even try. + */ + if (!nmi_uaccess_okay()) + return 0; + /* IRQs are off, so this synchronizes with smp_store_release */ - ldt = READ_ONCE(current->active_mm->context.ldt); + ldt = smp_load_acquire(¤t->mm->context.ldt); if (!ldt || idx >= ldt->nr_entries) return 0; diff --git a/arch/x86/lib/insn-eval.c b/arch/x86/lib/insn-eval.c index 98631c0e7a11..f786401ac15d 100644 --- a/arch/x86/lib/insn-eval.c +++ b/arch/x86/lib/insn-eval.c @@ -631,14 +631,21 @@ static bool get_desc(struct desc_struct *out, unsigned short sel) /* Bits [15:3] contain the index of the desired entry. */ sel >>= 3; - mutex_lock(¤t->active_mm->context.lock); - ldt = current->active_mm->context.ldt; + /* + * If we're not in a valid context with a real (not just lazy) + * user mm, then don't even try. + */ + if (!nmi_uaccess_okay()) + return false; + + mutex_lock(¤t->mm->context.lock); + ldt = current->mm->context.ldt; if (ldt && sel < ldt->nr_entries) { *out = ldt->entries[sel]; success = true; } - mutex_unlock(¤t->active_mm->context.lock); + mutex_unlock(¤t->mm->context.lock); return success; } |