diff options
author | Jeongjun Park <aha310510@gmail.com> | 2025-04-24 23:33:22 +0900 |
---|---|---|
committer | Andrew Morton <akpm@linux-foundation.org> | 2025-05-11 17:54:11 -0700 |
commit | d66adabe91803ef34a8b90613c81267b5ded1472 (patch) | |
tree | 531696eec31970f9806269c9882f0438787ba053 | |
parent | 9c7b53b21fb1df20f85e3822160b4687f98ff7b3 (diff) |
ipc: fix to protect IPCS lookups using RCU
syzbot reported that it discovered a use-after-free vulnerability, [0]
[0]: https://lore.kernel.org/all/67af13f8.050a0220.21dd3.0038.GAE@google.com/
idr_for_each() is protected by rwsem, but this is not enough. If it is
not protected by RCU read-critical region, when idr_for_each() calls
radix_tree_node_free() through call_rcu() to free the radix_tree_node
structure, the node will be freed immediately, and when reading the next
node in radix_tree_for_each_slot(), the already freed memory may be read.
Therefore, we need to add code to make sure that idr_for_each() is
protected within the RCU read-critical region when we call it in
shm_destroy_orphaned().
Link: https://lkml.kernel.org/r/20250424143322.18830-1-aha310510@gmail.com
Fixes: b34a6b1da371 ("ipc: introduce shm_rmid_forced sysctl")
Signed-off-by: Jeongjun Park <aha310510@gmail.com>
Reported-by: syzbot+a2b84e569d06ca3a949c@syzkaller.appspotmail.com
Cc: Jeongjun Park <aha310510@gmail.com>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Vasiliy Kulikov <segoon@openwall.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
-rw-r--r-- | ipc/shm.c | 5 |
1 files changed, 4 insertions, 1 deletions
diff --git a/ipc/shm.c b/ipc/shm.c index 99564c870084..492fcc699985 100644 --- a/ipc/shm.c +++ b/ipc/shm.c @@ -431,8 +431,11 @@ static int shm_try_destroy_orphaned(int id, void *p, void *data) void shm_destroy_orphaned(struct ipc_namespace *ns) { down_write(&shm_ids(ns).rwsem); - if (shm_ids(ns).in_use) + if (shm_ids(ns).in_use) { + rcu_read_lock(); idr_for_each(&shm_ids(ns).ipcs_idr, &shm_try_destroy_orphaned, ns); + rcu_read_unlock(); + } up_write(&shm_ids(ns).rwsem); } |