diff options
| author | Tomas Bortoli <tomasbortoli@gmail.com> | 2018-08-14 19:43:42 +0200 |
|---|---|---|
| committer | Dominique Martinet <dominique.martinet@cea.fr> | 2018-09-08 01:39:47 +0900 |
| commit | 728356dedeff8ef999cb436c71333ef4ac51a81c (patch) | |
| tree | ca05afe6f54f9f2bec2128f4cfd97cfc6ff23764 /include/net/9p | |
| parent | 43cbcbee9938b17f77cf34f1bc12d302f456810f (diff) | |
9p: Add refcount to p9_req_t
To avoid use-after-free(s), use a refcount to keep track of the
usable references to any instantiated struct p9_req_t.
This commit adds p9_req_put(), p9_req_get() and p9_req_try_get() as
wrappers to kref_put(), kref_get() and kref_get_unless_zero().
These are used by the client and the transports to keep track of
valid requests' references.
p9_free_req() is added back and used as callback by kref_put().
Add SLAB_TYPESAFE_BY_RCU as it ensures that the memory freed by
kmem_cache_free() will not be reused for another type until the rcu
synchronisation period is over, so an address gotten under rcu read
lock is safe to inc_ref() without corrupting random memory while
the lock is held.
Link: http://lkml.kernel.org/r/1535626341-20693-1-git-send-email-asmadeus@codewreck.org
Co-developed-by: Dominique Martinet <dominique.martinet@cea.fr>
Signed-off-by: Tomas Bortoli <tomasbortoli@gmail.com>
Reported-by: syzbot+467050c1ce275af2a5b8@syzkaller.appspotmail.com
Signed-off-by: Dominique Martinet <dominique.martinet@cea.fr>
Diffstat (limited to 'include/net/9p')
| -rw-r--r-- | include/net/9p/client.h | 14 |
1 files changed, 14 insertions, 0 deletions
diff --git a/include/net/9p/client.h b/include/net/9p/client.h index 735f3979d559..947a570307a6 100644 --- a/include/net/9p/client.h +++ b/include/net/9p/client.h @@ -94,6 +94,7 @@ enum p9_req_status_t { struct p9_req_t { int status; int t_err; + struct kref refcount; wait_queue_head_t wq; struct p9_fcall tc; struct p9_fcall rc; @@ -233,6 +234,19 @@ int p9_client_lock_dotl(struct p9_fid *fid, struct p9_flock *flock, u8 *status); int p9_client_getlock_dotl(struct p9_fid *fid, struct p9_getlock *fl); void p9_fcall_fini(struct p9_fcall *fc); struct p9_req_t *p9_tag_lookup(struct p9_client *, u16); + +static inline void p9_req_get(struct p9_req_t *r) +{ + kref_get(&r->refcount); +} + +static inline int p9_req_try_get(struct p9_req_t *r) +{ + return kref_get_unless_zero(&r->refcount); +} + +int p9_req_put(struct p9_req_t *r); + void p9_client_cb(struct p9_client *c, struct p9_req_t *req, int status); int p9_parse_header(struct p9_fcall *, int32_t *, int8_t *, int16_t *, int); |