NOMMU: Lock i_mmap_mutex for access to the VMA prio list
Lock i_mmap_mutex for access to the VMA prio list to prevent concurrent
access. Currently, certain parts of the mmap handling are protected by
the region mutex, but not all.
Reported-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Al Viro <viro@zeniv.linux.org.uk>
cc: stable@vger.kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/mm/nommu.c b/mm/nommu.c
index b982290..ee7e57e 100644
--- a/mm/nommu.c
+++ b/mm/nommu.c
@@ -696,9 +696,11 @@
if (vma->vm_file) {
mapping = vma->vm_file->f_mapping;
+ mutex_lock(&mapping->i_mmap_mutex);
flush_dcache_mmap_lock(mapping);
vma_prio_tree_insert(vma, &mapping->i_mmap);
flush_dcache_mmap_unlock(mapping);
+ mutex_unlock(&mapping->i_mmap_mutex);
}
/* add the VMA to the tree */
@@ -760,9 +762,11 @@
if (vma->vm_file) {
mapping = vma->vm_file->f_mapping;
+ mutex_lock(&mapping->i_mmap_mutex);
flush_dcache_mmap_lock(mapping);
vma_prio_tree_remove(vma, &mapping->i_mmap);
flush_dcache_mmap_unlock(mapping);
+ mutex_unlock(&mapping->i_mmap_mutex);
}
/* remove from the MM's tree and list */
@@ -2052,6 +2056,7 @@
high = (size + PAGE_SIZE - 1) >> PAGE_SHIFT;
down_write(&nommu_region_sem);
+ mutex_lock(&inode->i_mapping->i_mmap_mutex);
/* search for VMAs that fall within the dead zone */
vma_prio_tree_foreach(vma, &iter, &inode->i_mapping->i_mmap,
@@ -2059,6 +2064,7 @@
/* found one - only interested if it's shared out of the page
* cache */
if (vma->vm_flags & VM_SHARED) {
+ mutex_unlock(&inode->i_mapping->i_mmap_mutex);
up_write(&nommu_region_sem);
return -ETXTBSY; /* not quite true, but near enough */
}
@@ -2086,6 +2092,7 @@
}
}
+ mutex_unlock(&inode->i_mapping->i_mmap_mutex);
up_write(&nommu_region_sem);
return 0;
}