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author | Sungwoo Kim <iam@sung-woo.kim> | 2024-04-30 09:32:10 +0300 |
---|---|---|
committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2024-05-25 17:28:38 +0300 |
commit | 826af9d2f69567c646ff46d10393d47e30ad23c6 (patch) | |
tree | e97b62aec7f71f1a657932440e4ad74b37edddf3 | |
parent | 33a93dae2b8ac02b65940e4d0b43428118255760 (diff) | |
download | linux-826af9d2f69567c646ff46d10393d47e30ad23c6.tar.xz |
Bluetooth: L2CAP: Fix slab-use-after-free in l2cap_connect()
commit 4d7b41c0e43995b0e992b9f8903109275744b658 upstream.
Extend a critical section to prevent chan from early freeing.
Also make the l2cap_connect() return type void. Nothing is using the
returned value but it is ugly to return a potentially freed pointer.
Making it void will help with backports because earlier kernels did use
the return value. Now the compile will break for kernels where this
patch is not a complete fix.
Call stack summary:
[use]
l2cap_bredr_sig_cmd
l2cap_connect
┌ mutex_lock(&conn->chan_lock);
│ chan = pchan->ops->new_connection(pchan); <- alloc chan
│ __l2cap_chan_add(conn, chan);
│ l2cap_chan_hold(chan);
│ list_add(&chan->list, &conn->chan_l); ... (1)
└ mutex_unlock(&conn->chan_lock);
chan->conf_state ... (4) <- use after free
[free]
l2cap_conn_del
┌ mutex_lock(&conn->chan_lock);
│ foreach chan in conn->chan_l: ... (2)
│ l2cap_chan_put(chan);
│ l2cap_chan_destroy
│ kfree(chan) ... (3) <- chan freed
└ mutex_unlock(&conn->chan_lock);
==================================================================
BUG: KASAN: slab-use-after-free in instrument_atomic_read
include/linux/instrumented.h:68 [inline]
BUG: KASAN: slab-use-after-free in _test_bit
include/asm-generic/bitops/instrumented-non-atomic.h:141 [inline]
BUG: KASAN: slab-use-after-free in l2cap_connect+0xa67/0x11a0
net/bluetooth/l2cap_core.c:4260
Read of size 8 at addr ffff88810bf040a0 by task kworker/u3:1/311
Fixes: 73ffa904b782 ("Bluetooth: Move conf_{req,rsp} stuff to struct l2cap_chan")
Signed-off-by: Sungwoo Kim <iam@sung-woo.kim>
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r-- | net/bluetooth/l2cap_core.c | 21 |
1 files changed, 10 insertions, 11 deletions
diff --git a/net/bluetooth/l2cap_core.c b/net/bluetooth/l2cap_core.c index 5761d37c5537..9223b1a698e3 100644 --- a/net/bluetooth/l2cap_core.c +++ b/net/bluetooth/l2cap_core.c @@ -3905,13 +3905,12 @@ static inline int l2cap_command_rej(struct l2cap_conn *conn, return 0; } -static struct l2cap_chan *l2cap_connect(struct l2cap_conn *conn, - struct l2cap_cmd_hdr *cmd, - u8 *data, u8 rsp_code, u8 amp_id) +static void l2cap_connect(struct l2cap_conn *conn, struct l2cap_cmd_hdr *cmd, + u8 *data, u8 rsp_code, u8 amp_id) { struct l2cap_conn_req *req = (struct l2cap_conn_req *) data; struct l2cap_conn_rsp rsp; - struct l2cap_chan *chan = NULL, *pchan; + struct l2cap_chan *chan = NULL, *pchan = NULL; int result, status = L2CAP_CS_NO_INFO; u16 dcid = 0, scid = __le16_to_cpu(req->scid); @@ -3924,7 +3923,7 @@ static struct l2cap_chan *l2cap_connect(struct l2cap_conn *conn, &conn->hcon->dst, ACL_LINK); if (!pchan) { result = L2CAP_CR_BAD_PSM; - goto sendresp; + goto response; } mutex_lock(&conn->chan_lock); @@ -4011,17 +4010,15 @@ static struct l2cap_chan *l2cap_connect(struct l2cap_conn *conn, } response: - l2cap_chan_unlock(pchan); - mutex_unlock(&conn->chan_lock); - l2cap_chan_put(pchan); - -sendresp: rsp.scid = cpu_to_le16(scid); rsp.dcid = cpu_to_le16(dcid); rsp.result = cpu_to_le16(result); rsp.status = cpu_to_le16(status); l2cap_send_cmd(conn, cmd->ident, rsp_code, sizeof(rsp), &rsp); + if (!pchan) + return; + if (result == L2CAP_CR_PEND && status == L2CAP_CS_NO_INFO) { struct l2cap_info_req info; info.type = cpu_to_le16(L2CAP_IT_FEAT_MASK); @@ -4044,7 +4041,9 @@ sendresp: chan->num_conf_req++; } - return chan; + l2cap_chan_unlock(pchan); + mutex_unlock(&conn->chan_lock); + l2cap_chan_put(pchan); } static int l2cap_connect_req(struct l2cap_conn *conn, |