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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: 817e9f2c5c ("act_ife: acquire ife_mod_lock before reading ifeoplist")
Cc: Jamal Hadi Salim <jhs@mojatatu.com>
Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Cong Wang 2018-08-19 12:22:13 -07:00 committed by David S. Miller
parent 4e407ff5cd
commit 5ffe57da29
1 changed files with 21 additions and 13 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

34
net/sched/act_ife.c
View File

@ -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;
}