From: Jann Horn <jannh@xxxxxxxxxx>
[ Upstream commit c26958cb5a0d9053d1358258827638773f3d36ed ]
We need to take the mmap lock around find_vma() and subsequent use of the
VMA. Otherwise, we can race with concurrent operations like munmap(), which
can lead to use-after-free accesses to freed VMAs.
Fixes: 1000197d8013 ("nios2: System calls handling")
Signed-off-by: Jann Horn <jannh@xxxxxxxxxx>
Signed-off-by: Ley Foon Tan <ley.foon.tan@xxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
arch/nios2/kernel/sys_nios2.c | 11 +++++++++--
1 file changed, 9 insertions(+), 2 deletions(-)
diff --git a/arch/nios2/kernel/sys_nios2.c b/arch/nios2/kernel/sys_nios2.c
index cd390ec4f88bf..b1ca856999521 100644
--- a/arch/nios2/kernel/sys_nios2.c
+++ b/arch/nios2/kernel/sys_nios2.c
@@ -22,6 +22,7 @@ asmlinkage int sys_cacheflush(unsigned long addr, unsigned long len,
unsigned int op)
{
struct vm_area_struct *vma;
+ struct mm_struct *mm = current->mm;
if (len == 0)
return 0;
@@ -34,16 +35,22 @@ asmlinkage int sys_cacheflush(unsigned long addr, unsigned long len,
if (addr + len < addr)
return -EFAULT;
+ if (mmap_read_lock_killable(mm))
+ return -EINTR;
+
/*
* Verify that the specified address region actually belongs
* to this process.
*/
- vma = find_vma(current->mm, addr);
- if (vma == NULL || addr < vma->vm_start || addr + len > vma->vm_end)
+ vma = find_vma(mm, addr);
+ if (vma == NULL || addr < vma->vm_start || addr + len > vma->vm_end) {
+ mmap_read_unlock(mm);
return -EFAULT;
+ }
flush_cache_range(vma, addr, addr + len);
+ mmap_read_unlock(mm);
return 0;
}
--
2.27.0
