From 5ffe57da29b3802baeddaa40909682bbb4cb4d48 Mon Sep 17 00:00:00 2001 From: Cong Wang Date: Sun, 19 Aug 2018 12:22:13 -0700 Subject: [PATCH] act_ife: fix a potential deadlock use_all_metadata() acquires read_lock(&ife_mod_lock), then calls add_metainfo() which calls find_ife_oplist() which acquires the same lock again. Deadlock! Introduce __add_metainfo() which accepts struct tcf_meta_ops *ops as an additional parameter and let its callers to decide how to find it. For use_all_metadata(), it already has ops, no need to find it again, just call __add_metainfo() directly. And, as ife_mod_lock is only needed for find_ife_oplist(), this means we can make non-atomic allocation for populate_metalist() now. Fixes: 817e9f2c5c26 ("act_ife: acquire ife_mod_lock before reading ifeoplist") Cc: Jamal Hadi Salim Signed-off-by: Cong Wang Signed-off-by: David S. Miller --- net/sched/act_ife.c | 34 +++++++++++++++++++++------------- 1 file changed, 21 insertions(+), 13 deletions(-) diff --git a/net/sched/act_ife.c b/net/sched/act_ife.c index 244a8cf48183..196430aefe87 100644 --- a/net/sched/act_ife.c +++ b/net/sched/act_ife.c @@ -296,22 +296,16 @@ static int load_metaops_and_vet(u32 metaid, void *val, int len, bool rtnl_held) /* called when adding new meta information */ -static int add_metainfo(struct tcf_ife_info *ife, u32 metaid, void *metaval, - int len, bool atomic, bool exists) +static int __add_metainfo(const struct tcf_meta_ops *ops, + struct tcf_ife_info *ife, u32 metaid, void *metaval, + int len, bool atomic, bool exists) { struct tcf_meta_info *mi = NULL; - struct tcf_meta_ops *ops = find_ife_oplist(metaid); int ret = 0; - if (!ops) - return -ENOENT; - mi = kzalloc(sizeof(*mi), atomic ? GFP_ATOMIC : GFP_KERNEL); - if (!mi) { - /*put back what find_ife_oplist took */ - module_put(ops->owner); + if (!mi) return -ENOMEM; - } mi->metaid = metaid; mi->ops = ops; @@ -319,7 +313,6 @@ static int add_metainfo(struct tcf_ife_info *ife, u32 metaid, void *metaval, ret = ops->alloc(mi, metaval, atomic ? GFP_ATOMIC : GFP_KERNEL); if (ret != 0) { kfree(mi); - module_put(ops->owner); return ret; } } @@ -333,6 +326,21 @@ static int add_metainfo(struct tcf_ife_info *ife, u32 metaid, void *metaval, return ret; } +static int add_metainfo(struct tcf_ife_info *ife, u32 metaid, void *metaval, + int len, bool exists) +{ + const struct tcf_meta_ops *ops = find_ife_oplist(metaid); + int ret; + + if (!ops) + return -ENOENT; + ret = __add_metainfo(ops, ife, metaid, metaval, len, false, exists); + if (ret) + /*put back what find_ife_oplist took */ + module_put(ops->owner); + return ret; +} + static int use_all_metadata(struct tcf_ife_info *ife, bool exists) { struct tcf_meta_ops *o; @@ -341,7 +349,7 @@ static int use_all_metadata(struct tcf_ife_info *ife, bool exists) read_lock(&ife_mod_lock); list_for_each_entry(o, &ifeoplist, list) { - rc = add_metainfo(ife, o->metaid, NULL, 0, true, exists); + rc = __add_metainfo(o, ife, o->metaid, NULL, 0, true, exists); if (rc == 0) installed += 1; } @@ -435,7 +443,7 @@ static int populate_metalist(struct tcf_ife_info *ife, struct nlattr **tb, if (rc != 0) return rc; - rc = add_metainfo(ife, i, val, len, false, exists); + rc = add_metainfo(ife, i, val, len, exists); if (rc) return rc; } -- 2.30.2