arch_prctl(ARCH_FORCE_TAGGED_SVA) overrides the default and allows LAM
and SVA to co-exist in the process. It is expected by called by the
process when it knows what it is doing.
arch_prctl() operates on the current process, but the same code is
reachable from ptrace where it can be called on arbitrary task.
Make it strict and only allow to set MM_CONTEXT_FORCE_TAGGED_SVA for the
current process.
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
Fixes: 23e5d9ec2bab ("x86/mm/iommu/sva: Make LAM and SVA mutually exclusive")
Suggested-by: Dmitry Vyukov <dvyukov@xxxxxxxxxx>
---
arch/x86/kernel/process_64.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c
index c7dfd727c9ec..cefac2d3a9f6 100644
--- a/arch/x86/kernel/process_64.c
+++ b/arch/x86/kernel/process_64.c
@@ -885,6 +885,8 @@ long do_arch_prctl_64(struct task_struct *task, int option, unsigned long arg2)
case ARCH_ENABLE_TAGGED_ADDR:
return prctl_enable_tagged_addr(task->mm, arg2);
case ARCH_FORCE_TAGGED_SVA:
+ if (current != task)
+ return -EINVAL;
set_bit(MM_CONTEXT_FORCE_TAGGED_SVA, &task->mm->context.flags);
return 0;
case ARCH_GET_MAX_TAG_BITS:
--
2.39.2
