Bug 2334378 (CVE-2024-53186) - CVE-2024-53186 kernel: ksmbd: fix use-after-free in SMB request handling
Summary: CVE-2024-53186 kernel: ksmbd: fix use-after-free in SMB request handling
Keywords:
Status: NEW
Alias: CVE-2024-53186
Product: Security Response
Classification: Other
Component: vulnerability
Version: unspecified
Hardware: All
OS: Linux
high
high
Target Milestone: ---
Assignee: Product Security DevOps Team
QA Contact:
URL:
Whiteboard:
Depends On:
Blocks:
TreeView+ depends on / blocked
 
Reported: 2024-12-27 14:03 UTC by OSIDB Bzimport
Modified: 2025-01-20 14:02 UTC (History)
4 users (show)

Fixed In Version:
Clone Of:
Environment:
Last Closed:
Embargoed:


Attachments (Terms of Use)

Description OSIDB Bzimport 2024-12-27 14:03:02 UTC
In the Linux kernel, the following vulnerability has been resolved:

ksmbd: fix use-after-free in SMB request handling

A race condition exists between SMB request handling in
`ksmbd_conn_handler_loop()` and the freeing of `ksmbd_conn` in the
workqueue handler `handle_ksmbd_work()`. This leads to a UAF.
- KASAN: slab-use-after-free Read in handle_ksmbd_work
- KASAN: slab-use-after-free in rtlock_slowlock_locked

This race condition arises as follows:
- `ksmbd_conn_handler_loop()` waits for `conn->r_count` to reach zero:
  `wait_event(conn->r_count_q, atomic_read(&conn->r_count) == 0);`
- Meanwhile, `handle_ksmbd_work()` decrements `conn->r_count` using
  `atomic_dec_return(&conn->r_count)`, and if it reaches zero, calls
  `ksmbd_conn_free()`, which frees `conn`.
- However, after `handle_ksmbd_work()` decrements `conn->r_count`,
  it may still access `conn->r_count_q` in the following line:
  `waitqueue_active(&conn->r_count_q)` or `wake_up(&conn->r_count_q)`
  This results in a UAF, as `conn` has already been freed.

The discovery of this UAF can be referenced in the following PR for
syzkaller's support for SMB requests.

Comment 1 Avinash Hanwate 2024-12-28 13:35:03 UTC
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2024122721-CVE-2024-53186-7c05@gregkh/T


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