[PATCH 4.9 081/134] Take mmap lock in cacheflush syscall
From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Date: 2021-03-01 17:44:16
Also in:
lkml
Subsystem:
nios2 architecture, the rest · Maintainers:
Dinh Nguyen, Simon Schuster, Linus Torvalds
From: Jann Horn <jannh@google.com>
[ 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@google.com>
Signed-off-by: Ley Foon Tan <redacted>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
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