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authorJann Horn <jannh@google.com>2021-02-19 07:59:35 +0100
committerLey Foon Tan <ley.foon.tan@intel.com>2021-02-19 08:01:59 +0100
commitc26958cb5a0d9053d1358258827638773f3d36ed (patch)
tree26c85414097e72c6a4462d50f7fe23a5044a134f /arch/nios2
parentLinux 5.11 (diff)
downloadlinux-c26958cb5a0d9053d1358258827638773f3d36ed.tar.xz
linux-c26958cb5a0d9053d1358258827638773f3d36ed.zip
Take mmap lock in cacheflush syscall
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@google.com> Signed-off-by: Ley Foon Tan <ley.foon.tan@intel.com>
Diffstat (limited to 'arch/nios2')
-rw-r--r--arch/nios2/kernel/sys_nios2.c11
1 files changed, 9 insertions, 2 deletions
diff --git a/arch/nios2/kernel/sys_nios2.c b/arch/nios2/kernel/sys_nios2.c
index cd390ec4f88b..b1ca85699952 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;
}