@@ -1897,20 +1897,14 @@ static int snd_seq_ioctl_get_subscription(struct snd_seq_client *client,
int result;
struct snd_seq_client *sender = NULL;
struct snd_seq_client_port *sport = NULL;
- struct snd_seq_subscribers *p;
result = -EINVAL;
if ((sender = snd_seq_client_use_ptr(subs->sender.client)) == NULL)
goto __end;
if ((sport = snd_seq_port_use_ptr(sender, subs->sender.port)) == NULL)
goto __end;
- p = snd_seq_port_get_subscription(&sport->c_src, &subs->dest);
- if (p) {
- result = 0;
- *subs = p->info;
- } else
- result = -ENOENT;
-
+ result = snd_seq_port_get_subscription(&sport->c_src, &subs->dest,
+ subs);
__end:
if (sport)
snd_seq_port_unlock(sport);
@@ -632,20 +632,23 @@ int snd_seq_port_disconnect(struct snd_seq_client *connector,
/* get matched subscriber */
-struct snd_seq_subscribers *snd_seq_port_get_subscription(struct snd_seq_port_subs_info *src_grp,
- struct snd_seq_addr *dest_addr)
+int snd_seq_port_get_subscription(struct snd_seq_port_subs_info *src_grp,
+ struct snd_seq_addr *dest_addr,
+ struct snd_seq_port_subscribe *subs)
{
- struct snd_seq_subscribers *s, *found = NULL;
+ struct snd_seq_subscribers *s;
+ int err = -ENOENT;
down_read(&src_grp->list_mutex);
list_for_each_entry(s, &src_grp->list_head, src_list) {
if (addr_match(dest_addr, &s->info.dest)) {
- found = s;
+ *subs = s->info;
+ err = 0;
break;
}
}
up_read(&src_grp->list_mutex);
- return found;
+ return err;
}
/*
@@ -135,7 +135,8 @@ int snd_seq_port_subscribe(struct snd_seq_client_port *port,
struct snd_seq_port_subscribe *info);
/* get matched subscriber */
-struct snd_seq_subscribers *snd_seq_port_get_subscription(struct snd_seq_port_subs_info *src_grp,
- struct snd_seq_addr *dest_addr);
+int snd_seq_port_get_subscription(struct snd_seq_port_subs_info *src_grp,
+ struct snd_seq_addr *dest_addr,
+ struct snd_seq_port_subscribe *subs);
#endif
The snd_seq_ioctl_get_subscription() retrieves the port subscriber information as a pointer, while the object isn't protected, hence it may be deleted before the actual reference. This race was spotted by syzkaller and may lead to a UAF. The fix is simply copying the data in the lookup function that performs in the rwsem to protect against the deletion. Reported-by: syzbot+9437020c82413d00222d@syzkaller.appspotmail.com Signed-off-by: Takashi Iwai <tiwai@suse.de> --- sound/core/seq/seq_clientmgr.c | 10 ++-------- sound/core/seq/seq_ports.c | 13 ++++++++----- sound/core/seq/seq_ports.h | 5 +++-- 3 files changed, 13 insertions(+), 15 deletions(-)