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Message-Id: <20201013013416.390574-4-dima@arista.com>
Date: Tue, 13 Oct 2020 02:34:13 +0100
From: Dmitry Safonov <dima@...sta.com>
To: linux-kernel@...r.kernel.org
Cc: Dmitry Safonov <0x7f454c46@...il.com>,
Dmitry Safonov <dima@...sta.com>,
Alexander Viro <viro@...iv.linux.org.uk>,
Andrew Morton <akpm@...ux-foundation.org>,
Andy Lutomirski <luto@...nel.org>,
Brian Geffon <bgeffon@...gle.com>,
Catalin Marinas <catalin.marinas@....com>,
Dan Williams <dan.j.williams@...el.com>,
Dave Jiang <dave.jiang@...el.com>,
Hugh Dickins <hughd@...gle.com>,
Ingo Molnar <mingo@...hat.com>,
"Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
Mike Kravetz <mike.kravetz@...cle.com>,
Minchan Kim <minchan@...nel.org>,
Russell King <linux@...linux.org.uk>,
Thomas Bogendoerfer <tsbogend@...ha.franken.de>,
Thomas Gleixner <tglx@...utronix.de>,
Vishal Verma <vishal.l.verma@...el.com>,
Vlastimil Babka <vbabka@...e.cz>,
Will Deacon <will@...nel.org>, linux-aio@...ck.org,
linux-fsdevel@...r.kernel.org, linux-mm@...ck.org
Subject: [PATCH 3/6] mremap: Don't allow MREMAP_DONTUNMAP on special_mappings and aio
As kernel expect to see only one of such mappings, any further
operations on the VMA-copy may be unexpected by the kernel.
Maybe it's being on the safe side, but there doesn't seem to be any
expected use-case for this, so restrict it now.
Fixes: commit e346b3813067 ("mm/mremap: add MREMAP_DONTUNMAP to mremap()")
Signed-off-by: Dmitry Safonov <dima@...sta.com>
---
arch/x86/kernel/cpu/resctrl/pseudo_lock.c | 2 +-
fs/aio.c | 5 ++++-
include/linux/mm.h | 2 +-
mm/mmap.c | 6 +++++-
mm/mremap.c | 2 +-
5 files changed, 12 insertions(+), 5 deletions(-)
diff --git a/arch/x86/kernel/cpu/resctrl/pseudo_lock.c b/arch/x86/kernel/cpu/resctrl/pseudo_lock.c
index 0daf2f1cf7a8..e916646adc69 100644
--- a/arch/x86/kernel/cpu/resctrl/pseudo_lock.c
+++ b/arch/x86/kernel/cpu/resctrl/pseudo_lock.c
@@ -1458,7 +1458,7 @@ static int pseudo_lock_dev_release(struct inode *inode, struct file *filp)
return 0;
}
-static int pseudo_lock_dev_mremap(struct vm_area_struct *area)
+static int pseudo_lock_dev_mremap(struct vm_area_struct *area, unsigned long flags)
{
/* Not supported */
return -EINVAL;
diff --git a/fs/aio.c b/fs/aio.c
index d5ec30385566..3be3c0f77548 100644
--- a/fs/aio.c
+++ b/fs/aio.c
@@ -324,13 +324,16 @@ static void aio_free_ring(struct kioctx *ctx)
}
}
-static int aio_ring_mremap(struct vm_area_struct *vma)
+static int aio_ring_mremap(struct vm_area_struct *vma, unsigned long flags)
{
struct file *file = vma->vm_file;
struct mm_struct *mm = vma->vm_mm;
struct kioctx_table *table;
int i, res = -EINVAL;
+ if (flags & MREMAP_DONTUNMAP)
+ return -EINVAL;
+
spin_lock(&mm->ioctx_lock);
rcu_read_lock();
table = rcu_dereference(mm->ioctx_table);
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 16b799a0522c..fd51a4a1f722 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -550,7 +550,7 @@ struct vm_operations_struct {
void (*open)(struct vm_area_struct * area);
void (*close)(struct vm_area_struct * area);
int (*split)(struct vm_area_struct * area, unsigned long addr);
- int (*mremap)(struct vm_area_struct * area);
+ int (*mremap)(struct vm_area_struct *area, unsigned long flags);
vm_fault_t (*fault)(struct vm_fault *vmf);
vm_fault_t (*huge_fault)(struct vm_fault *vmf,
enum page_entry_size pe_size);
diff --git a/mm/mmap.c b/mm/mmap.c
index bdd19f5b994e..50f853b0ec39 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -3372,10 +3372,14 @@ static const char *special_mapping_name(struct vm_area_struct *vma)
return ((struct vm_special_mapping *)vma->vm_private_data)->name;
}
-static int special_mapping_mremap(struct vm_area_struct *new_vma)
+static int special_mapping_mremap(struct vm_area_struct *new_vma,
+ unsigned long flags)
{
struct vm_special_mapping *sm = new_vma->vm_private_data;
+ if (flags & MREMAP_DONTUNMAP)
+ return -EINVAL;
+
if (WARN_ON_ONCE(current->mm != new_vma->vm_mm))
return -EFAULT;
diff --git a/mm/mremap.c b/mm/mremap.c
index c248f9a52125..898e9818ba6d 100644
--- a/mm/mremap.c
+++ b/mm/mremap.c
@@ -384,7 +384,7 @@ static unsigned long move_vma(struct vm_area_struct *vma,
if (moved_len < old_len) {
err = -ENOMEM;
} else if (vma->vm_ops && vma->vm_ops->mremap) {
- err = vma->vm_ops->mremap(new_vma);
+ err = vma->vm_ops->mremap(new_vma, flags);
}
if (unlikely(err)) {
--
2.28.0
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