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authorDavid Howells <dhowells@redhat.com>2007-02-06 13:45:51 +0000
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2007-02-06 14:45:00 -0800
commit9ad0830f307bcd8dc285cfae58998d43b21727f4 (patch)
tree237119861640847301c6af758650b05ea353a1da /security
parent768c242b30d9ec5581dd245e8289acb6b77815d1 (diff)
downloadlinux-2.6.34-ux500-9ad0830f307bcd8dc285cfae58998d43b21727f4.tar.gz
[PATCH] Keys: Fix key serial number collision handling
Fix the key serial number collision avoidance code in key_alloc_serial(). This didn't use to be so much of a problem as the key serial numbers were allocated from a simple incremental counter, and it would have to go through two billion keys before it could possibly encounter a collision. However, now that random numbers are used instead, collisions are much more likely. This is fixed by finding a hole in the rbtree where the next unused serial number ought to be and using that by going almost back to the top of the insertion routine and redoing the insertion with the new serial number rather than trying to be clever and attempting to work out the insertion point pointer directly. This fixes kernel BZ #7727. Signed-off-by: David Howells <dhowells@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'security')
-rw-r--r--security/keys/key.c33
1 files changed, 14 insertions, 19 deletions
diff --git a/security/keys/key.c b/security/keys/key.c
index ac9326c5f1d..700400d801d 100644
--- a/security/keys/key.c
+++ b/security/keys/key.c
@@ -188,6 +188,7 @@ static inline void key_alloc_serial(struct key *key)
spin_lock(&key_serial_lock);
+attempt_insertion:
parent = NULL;
p = &key_serial_tree.rb_node;
@@ -202,39 +203,33 @@ static inline void key_alloc_serial(struct key *key)
else
goto serial_exists;
}
- goto insert_here;
+
+ /* we've found a suitable hole - arrange for this key to occupy it */
+ rb_link_node(&key->serial_node, parent, p);
+ rb_insert_color(&key->serial_node, &key_serial_tree);
+
+ spin_unlock(&key_serial_lock);
+ return;
/* we found a key with the proposed serial number - walk the tree from
* that point looking for the next unused serial number */
serial_exists:
for (;;) {
key->serial++;
- if (key->serial < 2)
- key->serial = 2;
-
- if (!rb_parent(parent))
- p = &key_serial_tree.rb_node;
- else if (rb_parent(parent)->rb_left == parent)
- p = &(rb_parent(parent)->rb_left);
- else
- p = &(rb_parent(parent)->rb_right);
+ if (key->serial < 3) {
+ key->serial = 3;
+ goto attempt_insertion;
+ }
parent = rb_next(parent);
if (!parent)
- break;
+ goto attempt_insertion;
xkey = rb_entry(parent, struct key, serial_node);
if (key->serial < xkey->serial)
- goto insert_here;
+ goto attempt_insertion;
}
- /* we've found a suitable hole - arrange for this key to occupy it */
-insert_here:
- rb_link_node(&key->serial_node, parent, p);
- rb_insert_color(&key->serial_node, &key_serial_tree);
-
- spin_unlock(&key_serial_lock);
-
} /* end key_alloc_serial() */
/*****************************************************************************/