CVE-2024-36013

Published: May 24, 2024Last modified: May 24, 2024

Description

In the Linux kernel, the following vulnerability has been resolved: Bluetooth: L2CAP: Fix slab-use-after-free in l2cap_connect() 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

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References

• http://www.openwall.com/lists/oss-security/2024/05/30/1
• http://www.openwall.com/lists/oss-security/2024/05/30/2
• https://git.kernel.org/stable/c/4d7b41c0e43995b0e992b9f8903109275744b658
• https://git.kernel.org/stable/c/826af9d2f69567c646ff46d10393d47e30ad23c6
• https://git.kernel.org/stable/c/cfe560c7050bfb37b0d2491bbe7cd8b59e77fdc5