CVE-2026-68188: Bluetooth: RFCOMM: Fix session UAF in set_termios
Greg Kroah-Hartman <[email protected]>
| Newsgroups | org.kernel.vger.linux-cve-announce |
|---|---|
| Message-ID | <2026081009-CVE-2026-68188-8015@gregkh> |
From: Greg Kroah-Hartman <[email protected]> Description =========== In the Linux kernel, the following vulnerability has been resolved: Bluetooth: RFCOMM: Fix session UAF in set_termios rfcomm_tty_set_termios() tests dlc->session without rfcomm_mutex and later passes the pointer to rfcomm_send_rpn(). The latter dereferences both session->initiator and session->sock. Meanwhile, krfcommd can unlink the DLC and free the session while holding rfcomm_mutex. The race can proceed as follows: TTY ioctl task krfcommd -------------- -------- load dlc->session enter rfcomm_send_rpn() lock rfcomm_mutex clear dlc->session free session unlock rfcomm_mutex read session->initiator KASAN reported: BUG: KASAN: slab-use-after-free in rfcomm_send_rpn+0x297/0x2a0 Read of size 4 at addr ffff88810012a850 by task poc/92 Call Trace: rfcomm_send_rpn+0x297/0x2a0 rfcomm_tty_set_termios+0x50d/0x850 tty_set_termios+0x596/0x950 set_termios+0x46a/0x6e0 tty_mode_ioctl+0x152/0xbd0 tty_ioctl+0x915/0x1240 __x64_sys_ioctl+0x134/0x1c0 Allocated by task 92: rfcomm_session_add+0x9e/0x2e0 rfcomm_dlc_open+0x8b1/0xe00 rfcomm_dev_activate+0x85/0x1a0 rfcomm_tty_open+0x90/0x280 Freed by task 68: kfree+0x131/0x3c0 rfcomm_session_del+0x119/0x180 rfcomm_run+0x737/0x4710 Add rfcomm_dlc_send_rpn(), which holds rfcomm_mutex while it verifies that the DLC is still attached and sends the RPN frame. Have the TTY path use the helper and drop its unlocked session check. This keeps the session valid through both the frame construction and socket send. The Linux kernel CVE team has assigned CVE-2026-68188 to this issue. Affected and fixed versions =========================== Issue introduced in 2.6.14 with commit 3a5e903c09aed19ca4a1bb26d87b8d6461a93818 and fixed in 6.6.148 with commit 2894bd8c68e97accd758ca6e5fc375d7e9e8882c Issue introduced in 2.6.14 with commit 3a5e903c09aed19ca4a1bb26d87b8d6461a93818 and fixed in 6.12.101 with commit a82a9d3891f5607030b0672c255087a12bb9837b Issue introduced in 2.6.14 with commit 3a5e903c09aed19ca4a1bb26d87b8d6461a93818 and fixed in 6.18.42 with commit 780b04d09c941262ee2a2b4a09906451b69df8a6 Issue introduced in 2.6.14 with commit 3a5e903c09aed19ca4a1bb26d87b8d6461a93818 and fixed in 7.1.6 with commit 98bc68194e37bfa5e8ddc80b5c1eb0be4dc607ea Issue introduced in 2.6.14 with commit 3a5e903c09aed19ca4a1bb26d87b8d6461a93818 and fixed in 7.2-rc5 with commit c783399efc22d035443f1dfbf2a09bf9562aaa5e Please see https://www.kernel.org for a full list of currently supported kernel versions by the kernel community. Unaffected versions might change over time as fixes are backported to older supported kernel versions. The official CVE entry at https://cve.org/CVERecord/?id=CVE-2026-68188 will be updated if fixes are backported, please check that for the most up to date information about this issue. Affected files ============== The file(s) affected by this issue are: include/net/bluetooth/rfcomm.h net/bluetooth/rfcomm/core.c net/bluetooth/rfcomm/tty.c Mitigation ========== The Linux kernel CVE team recommends that you update to the latest stable kernel version for this, and many other bugfixes. Individual changes are never tested alone, but rather are part of a larger kernel release. Cherry-picking individual commits is not recommended or supported by the Linux kernel community at all. If however, updating to the latest release is impossible, the individual changes to resolve this issue can be found at these commits: https://git.kernel.org/stable/c/2894bd8c68e97accd758ca6e5fc375d7e9e8882c https://git.kernel.org/stable/c/a82a9d3891f5607030b0672c255087a12bb9837b https://git.kernel.org/stable/c/780b04d09c941262ee2a2b4a09906451b69df8a6 https://git.kernel.org/stable/c/98bc68194e37bfa5e8ddc80b5c1eb0be4dc607ea https://git.kernel.org/stable/c/c783399efc22d035443f1dfbf2a09bf9562aaa5e