If @mm is not the same as current->mm, mpx_notify_unmap() will yield
invalid results and at worst will lead to a crash if it gets called by a
kthread.
The function in question gets called through do_munmap(). ATM kernel does
not use that function on x86 in such context that mm and current->mm would
differ
With the addition of SGX driver code, do_munmap() is called from workqueue
thread. This commit changes the parameter passed to @mm so that this will
yield the correct results and not crash as reference to current->mm would
be NULL in a kthread context.
Cc: Dave Hansen <dave.hansen@xxxxxxxxx>
Fixes: 1de4fa14ee25 ("x86, mpx: Cleanup unused bound tables")
Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@xxxxxxxxxxxxxxx>
---
arch/x86/mm/mpx.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/arch/x86/mm/mpx.c b/arch/x86/mm/mpx.c
index 2385538e8065..15fb62657ee9 100644
--- a/arch/x86/mm/mpx.c
+++ b/arch/x86/mm/mpx.c
@@ -882,7 +882,7 @@ static int mpx_unmap_tables(struct mm_struct *mm,
* necessary, and the 'vma' is the first vma in this range (start -> end).
*/
void mpx_notify_unmap(struct mm_struct *mm, struct vm_area_struct *vma,
- unsigned long start, unsigned long end)
+ unsigned long start, unsigned long end)
{
int ret;
@@ -890,7 +890,7 @@ void mpx_notify_unmap(struct mm_struct *mm, struct vm_area_struct *vma,
* Refuse to do anything unless userspace has asked
* the kernel to help manage the bounds tables,
*/
- if (!kernel_managing_mpx_tables(current->mm))
+ if (!kernel_managing_mpx_tables(mm))
return;
/*
* This will look across the entire 'start -> end' range,
--
2.19.1
