net: genetlink: always allocate separate attrs for dumpit ops

Individual dumpit ops (start, dumpit, done) are locked by genl_lock
if !family->parallel_ops. However, multiple
genl_family_rcv_msg_dumpit() calls may in in flight in parallel.
Each has a separate struct genl_dumpit_info allocated
but they share the same family->attrbuf. Fix this by allocating separate
memory for attrs for dumpit ops, for non-parallel_ops (for parallel_ops
it is done already).

Reported-by: syzbot+495688b736534bb6c6ad@syzkaller.appspotmail.com
Reported-by: syzbot+ff59dc711f2cff879a05@syzkaller.appspotmail.com
Reported-by: syzbot+dbe02e13bcce52bcf182@syzkaller.appspotmail.com
Reported-by: syzbot+9cb7edb2906ea1e83006@syzkaller.appspotmail.com
Fixes: bf813b0afeae ("net: genetlink: parse attrs and store in contect info struct during dumpit")
Signed-off-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>

diff --git a/net/netlink/genetlink.c b/net/netlink/genetlink.c
index 1b50464..ecc2bd3 100644 (file)
--- a/net/netlink/genetlink.c
+++ b/net/netlink/genetlink.c
@@ -474,7 +474,8 @@ genl_family_rcv_msg_attrs_parse(const struct genl_family *family,
                                struct netlink_ext_ack *extack,
                                const struct genl_ops *ops,
                                int hdrlen,
-                               enum genl_validate_flags no_strict_flag)
+                               enum genl_validate_flags no_strict_flag,
+                               bool parallel)
 {
        enum netlink_validation validate = ops->validate & no_strict_flag ?
                                           NL_VALIDATE_LIBERAL :
@@ -482,7 +483,7 @@ genl_family_rcv_msg_attrs_parse(const struct genl_family *family,
        struct nlattr **attrbuf;
        int err;
 
-       if (family->maxattr && family->parallel_ops) {
+       if (parallel) {
                attrbuf = kmalloc_array(family->maxattr + 1,
                                        sizeof(struct nlattr *), GFP_KERNEL);
                if (!attrbuf)
@@ -493,7 +494,7 @@ genl_family_rcv_msg_attrs_parse(const struct genl_family *family,
 
        err = __nlmsg_parse(nlh, hdrlen, attrbuf, family->maxattr,
                            family->policy, validate, extack);
-       if (err && family->maxattr && family->parallel_ops) {
+       if (err && parallel) {
                kfree(attrbuf);
                return ERR_PTR(err);
        }
@@ -501,9 +502,10 @@ genl_family_rcv_msg_attrs_parse(const struct genl_family *family,
 }
 
 static void genl_family_rcv_msg_attrs_free(const struct genl_family *family,
-                                          struct nlattr **attrbuf)
+                                          struct nlattr **attrbuf,
+                                          bool parallel)
 {
-       if (family->maxattr && family->parallel_ops)
+       if (parallel)
                kfree(attrbuf);
 }
 
@@ -542,7 +544,7 @@ static int genl_lock_done(struct netlink_callback *cb)
                rc = ops->done(cb);
                genl_unlock();
        }
-       genl_family_rcv_msg_attrs_free(info->family, info->attrs);
+       genl_family_rcv_msg_attrs_free(info->family, info->attrs, true);
        genl_dumpit_info_free(info);
        return rc;
 }
@@ -555,7 +557,7 @@ static int genl_parallel_done(struct netlink_callback *cb)
 
        if (ops->done)
                rc = ops->done(cb);
-       genl_family_rcv_msg_attrs_free(info->family, info->attrs);
+       genl_family_rcv_msg_attrs_free(info->family, info->attrs, true);
        genl_dumpit_info_free(info);
        return rc;
 }
@@ -585,7 +587,8 @@ static int genl_family_rcv_msg_dumpit(const struct genl_family *family,
 
        attrs = genl_family_rcv_msg_attrs_parse(family, nlh, extack,
                                                ops, hdrlen,
-                                               GENL_DONT_VALIDATE_DUMP_STRICT);
+                                               GENL_DONT_VALIDATE_DUMP_STRICT,
+                                               true);
        if (IS_ERR(attrs))
                return PTR_ERR(attrs);
 
@@ -593,7 +596,7 @@ no_attrs:
        /* Allocate dumpit info. It is going to be freed by done() callback. */
        info = genl_dumpit_info_alloc();
        if (!info) {
-               genl_family_rcv_msg_attrs_free(family, attrs);
+               genl_family_rcv_msg_attrs_free(family, attrs, true);
                return -ENOMEM;
        }
 
@@ -645,7 +648,9 @@ static int genl_family_rcv_msg_doit(const struct genl_family *family,
 
        attrbuf = genl_family_rcv_msg_attrs_parse(family, nlh, extack,
                                                  ops, hdrlen,
-                                                 GENL_DONT_VALIDATE_STRICT);
+                                                 GENL_DONT_VALIDATE_STRICT,
+                                                 family->maxattr &&
+                                                 family->parallel_ops);
        if (IS_ERR(attrbuf))
                return PTR_ERR(attrbuf);
 
@@ -671,7 +676,8 @@ static int genl_family_rcv_msg_doit(const struct genl_family *family,
                family->post_doit(ops, skb, &info);
 
 out:
-       genl_family_rcv_msg_attrs_free(family, attrbuf);
+       genl_family_rcv_msg_attrs_free(family, attrbuf,
+                                      family->maxattr && family->parallel_ops);
 
        return err;
 }