summaryrefslogtreecommitdiff
diff options
context:
space:
mode:
authorHerbert Xu <herbert@gondor.apana.org.au>2020-07-24 13:12:53 +0300
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2020-08-05 10:59:47 +0300
commitc3883876d3f154d4eb3c9a4406c0489996806e0d (patch)
tree5029613578f3fa4199a75b0b9a51965697baf5cb
parentb1d629d329107a499798037982156fd5457b3a44 (diff)
downloadlinux-c3883876d3f154d4eb3c9a4406c0489996806e0d.tar.xz
rhashtable: Fix unprotected RCU dereference in __rht_ptr
[ Upstream commit 1748f6a2cbc4694523f16da1c892b59861045b9d ] The rcu_dereference call in rht_ptr_rcu is completely bogus because we've already dereferenced the value in __rht_ptr and operated on it. This causes potential double readings which could be fatal. The RCU dereference must occur prior to the comparison in __rht_ptr. This patch changes the order of RCU dereference so that it is done first and the result is then fed to __rht_ptr. The RCU marking changes have been minimised using casts which will be removed in a follow-up patch. Fixes: ba6306e3f648 ("rhashtable: Remove RCU marking from...") Reported-by: "Gong, Sishuai" <sishuai@purdue.edu> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Sasha Levin <sashal@kernel.org>
-rw-r--r--include/linux/rhashtable.h25
1 files changed, 13 insertions, 12 deletions
diff --git a/include/linux/rhashtable.h b/include/linux/rhashtable.h
index beb9a9da1699..c5bf21261bb1 100644
--- a/include/linux/rhashtable.h
+++ b/include/linux/rhashtable.h
@@ -349,11 +349,11 @@ static inline void rht_unlock(struct bucket_table *tbl,
local_bh_enable();
}
-static inline struct rhash_head __rcu *__rht_ptr(
- struct rhash_lock_head *const *bkt)
+static inline struct rhash_head *__rht_ptr(
+ struct rhash_lock_head *p, struct rhash_lock_head __rcu *const *bkt)
{
- return (struct rhash_head __rcu *)
- ((unsigned long)*bkt & ~BIT(0) ?:
+ return (struct rhash_head *)
+ ((unsigned long)p & ~BIT(0) ?:
(unsigned long)RHT_NULLS_MARKER(bkt));
}
@@ -365,25 +365,26 @@ static inline struct rhash_head __rcu *__rht_ptr(
* access is guaranteed, such as when destroying the table.
*/
static inline struct rhash_head *rht_ptr_rcu(
- struct rhash_lock_head *const *bkt)
+ struct rhash_lock_head *const *p)
{
- struct rhash_head __rcu *p = __rht_ptr(bkt);
-
- return rcu_dereference(p);
+ struct rhash_lock_head __rcu *const *bkt = (void *)p;
+ return __rht_ptr(rcu_dereference(*bkt), bkt);
}
static inline struct rhash_head *rht_ptr(
- struct rhash_lock_head *const *bkt,
+ struct rhash_lock_head *const *p,
struct bucket_table *tbl,
unsigned int hash)
{
- return rht_dereference_bucket(__rht_ptr(bkt), tbl, hash);
+ struct rhash_lock_head __rcu *const *bkt = (void *)p;
+ return __rht_ptr(rht_dereference_bucket(*bkt, tbl, hash), bkt);
}
static inline struct rhash_head *rht_ptr_exclusive(
- struct rhash_lock_head *const *bkt)
+ struct rhash_lock_head *const *p)
{
- return rcu_dereference_protected(__rht_ptr(bkt), 1);
+ struct rhash_lock_head __rcu *const *bkt = (void *)p;
+ return __rht_ptr(rcu_dereference_protected(*bkt, 1), bkt);
}
static inline void rht_assign_locked(struct rhash_lock_head **bkt,