From: Sungwoo Kim iam@sung-woo.kim
mainline inclusion from mainline-v6.9 commit 4d7b41c0e43995b0e992b9f8903109275744b658 category: bugfix bugzilla: https://gitee.com/src-openeuler/kernel/issues/I9RMPS CVE: CVE-2024-36013
Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i...
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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 Conflicts: net/bluetooth/l2cap_core.c [The version does not include commit e7b02296fb40, so the return value of l2cap_connect() is still used in l2cap_create_channel_req().] Signed-off-by: Ziyang Xuan william.xuanziyang@huawei.com --- net/bluetooth/l2cap_core.c | 16 +++++++++------- 1 file changed, 9 insertions(+), 7 deletions(-)
diff --git a/net/bluetooth/l2cap_core.c b/net/bluetooth/l2cap_core.c index cf78a48085ed..b450f1736c7b 100644 --- a/net/bluetooth/l2cap_core.c +++ b/net/bluetooth/l2cap_core.c @@ -4129,7 +4129,7 @@ static struct l2cap_chan *l2cap_connect(struct l2cap_conn *conn, { 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); @@ -4142,7 +4142,7 @@ 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); @@ -4230,17 +4230,15 @@ 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 NULL; + if (result == L2CAP_CR_PEND && status == L2CAP_CS_NO_INFO) { struct l2cap_info_req info; info.type = cpu_to_le16(L2CAP_IT_FEAT_MASK); @@ -4263,6 +4261,10 @@ static struct l2cap_chan *l2cap_connect(struct l2cap_conn *conn, chan->num_conf_req++; }
+ l2cap_chan_unlock(pchan); + mutex_unlock(&conn->chan_lock); + l2cap_chan_put(pchan); + return chan; }