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authorJan Kara <jack@suse.cz>2013-11-12 15:11:19 -0800
committerChanho Park <chanho61.park@samsung.com>2014-03-20 17:44:44 +0900
commit6a139b83f6e16924e3a8d612335411f38e901823 (patch)
treeb29bfa241a78b24fdaab0fb9017d8f9362f64dd3
parent67d807339379a050b370c888a0d883eafd482ec8 (diff)
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rbtree: fix rbtree_postorder_for_each_entry_safe() iterator
The iterator rbtree_postorder_for_each_entry_safe() relies on pointer underflow behavior when testing for loop termination. In particular it expects that &rb_entry(NULL, type, field)->field is NULL. But the result of this expression is not defined by a C standard and some gcc versions (e.g. 4.3.4) assume the above expression can never be equal to NULL. The net result is an oops because the iteration is not properly terminated. Fix the problem by modifying the iterator to avoid pointer underflows. Change-Id: I06d5983b5335412be6cb6ebd95db3c682e26ed38 Signed-off-by: Jan Kara <jack@suse.cz> Signed-off-by: Cody P Schafer <cody@linux.vnet.ibm.com> Cc: Michel Lespinasse <walken@google.com> Cc: "David S. Miller" <davem@davemloft.net> Cc: Adrian Hunter <adrian.hunter@intel.com> Cc: Artem Bityutskiy <dedekind1@gmail.com> Cc: David Woodhouse <dwmw2@infradead.org> Cc: Jozsef Kadlecsik <kadlec@blackhole.kfki.hu> Cc: Pablo Neira Ayuso <pablo@netfilter.org> Cc: Patrick McHardy <kaber@trash.net> Cc: Paul Mundt <lethal@linux-sh.org> Cc: Theodore Ts'o <tytso@mit.edu> Cc: <stable@vger.kernel.org> [3.12.x] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--include/linux/rbtree.h16
1 files changed, 9 insertions, 7 deletions
diff --git a/include/linux/rbtree.h b/include/linux/rbtree.h
index aa870a4ddf5..57e75ae9910 100644
--- a/include/linux/rbtree.h
+++ b/include/linux/rbtree.h
@@ -85,6 +85,11 @@ static inline void rb_link_node(struct rb_node * node, struct rb_node * parent,
*rb_link = node;
}
+#define rb_entry_safe(ptr, type, member) \
+ ({ typeof(ptr) ____ptr = (ptr); \
+ ____ptr ? rb_entry(____ptr, type, member) : NULL; \
+ })
+
/**
* rbtree_postorder_for_each_entry_safe - iterate over rb_root in post order of
* given type safe against removal of rb_node entry
@@ -95,12 +100,9 @@ static inline void rb_link_node(struct rb_node * node, struct rb_node * parent,
* @field: the name of the rb_node field within 'type'.
*/
#define rbtree_postorder_for_each_entry_safe(pos, n, root, field) \
- for (pos = rb_entry(rb_first_postorder(root), typeof(*pos), field),\
- n = rb_entry(rb_next_postorder(&pos->field), \
- typeof(*pos), field); \
- &pos->field; \
- pos = n, \
- n = rb_entry(rb_next_postorder(&pos->field), \
- typeof(*pos), field))
+ for (pos = rb_entry_safe(rb_first_postorder(root), typeof(*pos), field); \
+ pos && ({ n = rb_entry_safe(rb_next_postorder(&pos->field), \
+ typeof(*pos), field); 1; }); \
+ pos = n)
#endif /* _LINUX_RBTREE_H */