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| 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 /net/9p/trans_fd.c | |
| parent | 43cbcbee9938b17f77cf34f1bc12d302f456810f (diff) | |
| download | linux-728356dedeff8ef999cb436c71333ef4ac51a81c.tar.bz2 | |
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 'net/9p/trans_fd.c')
| -rw-r--r-- | net/9p/trans_fd.c | 11 |
1 files changed, 10 insertions, 1 deletions
diff --git a/net/9p/trans_fd.c b/net/9p/trans_fd.c index 51615c0fb744..aca528722183 100644 --- a/net/9p/trans_fd.c +++ b/net/9p/trans_fd.c @@ -132,6 +132,7 @@ struct p9_conn { struct list_head req_list; struct list_head unsent_req_list; struct p9_req_t *req; + struct p9_req_t *wreq; char tmp_buf[7]; struct p9_fcall rc; int wpos; @@ -383,6 +384,7 @@ static void p9_read_work(struct work_struct *work) m->rc.sdata = NULL; m->rc.offset = 0; m->rc.capacity = 0; + p9_req_put(m->req); m->req = NULL; } @@ -472,6 +474,8 @@ static void p9_write_work(struct work_struct *work) m->wbuf = req->tc.sdata; m->wsize = req->tc.size; m->wpos = 0; + p9_req_get(req); + m->wreq = req; spin_unlock(&m->client->lock); } @@ -492,8 +496,11 @@ static void p9_write_work(struct work_struct *work) } m->wpos += err; - if (m->wpos == m->wsize) + if (m->wpos == m->wsize) { m->wpos = m->wsize = 0; + p9_req_put(m->wreq); + m->wreq = NULL; + } end_clear: clear_bit(Wworksched, &m->wsched); @@ -694,6 +701,7 @@ static int p9_fd_cancel(struct p9_client *client, struct p9_req_t *req) if (req->status == REQ_STATUS_UNSENT) { list_del(&req->req_list); req->status = REQ_STATUS_FLSHD; + p9_req_put(req); ret = 0; } spin_unlock(&client->lock); @@ -711,6 +719,7 @@ static int p9_fd_cancelled(struct p9_client *client, struct p9_req_t *req) spin_lock(&client->lock); list_del(&req->req_list); spin_unlock(&client->lock); + p9_req_put(req); return 0; } |