{"id":"CVE-2026-98455","title":"Bluetooth: RFCOMM: fix NULL dereference of dlc->session in RFCOMM_CONNINFO","summary":"In the Linux kernel, the following vulnerability has been resolved:\n\nBluetooth: RFCOMM: fix NULL dereference of dlc->session in RFCOMM_CONNINFO\n\nThe RFCOMM_CONNINFO getsockopt handler accepts a socket that is not\nconnected as long as def…","severity":"none","vendor":"Linux","product":"Linux","affected":["Linux >= bb23c0ab824653be4aa7dfca15b07b3059717004 < c3aee3fc1287c8a555baf3895959087cb0c33fe8","Linux >= bb23c0ab824653be4aa7dfca15b07b3059717004 < 4bf5ca47203049ce3648f750a53dcdc98bcc9e3e","Linux >= bb23c0ab824653be4aa7dfca15b07b3059717004 < 1c4f7e1177da2f229be04139c27e5370a1cfba52","Linux >= bb23c0ab824653be4aa7dfca15b07b3059717004 < 84ae3cfd7d3a63591a2eb4faa24faf678c6708aa","Linux >= bb23c0ab824653be4aa7dfca15b07b3059717004 < c7362f6a18ed167f52f08ce25eeec8a7818c5004","Linux >= bb23c0ab824653be4aa7dfca15b07b3059717004 < 8f5b30cc12c409ff62891e47ed51e6bf0945a3ea","Linux >= bb23c0ab824653be4aa7dfca15b07b3059717004 < 005b23d9e324fe5d0acbcfa70c625f2e81189046","Linux >= bb23c0ab824653be4aa7dfca15b07b3059717004 < 46f8ffd0a1f1eb6cbc94946a92c11ef601e228a1","Linux 2.6.30"],"published":"2026-10-18","updated":"2026-10-18","sourceUpdated":"2026-10-18T15:15:04.988Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-98455","references":[{"url":"https://git.kernel.org/stable/c/c3aee3fc1287c8a555baf3895959087cb0c33fe8"},{"url":"https://git.kernel.org/stable/c/4bf5ca47203049ce3648f750a53dcdc98bcc9e3e"},{"url":"https://git.kernel.org/stable/c/1c4f7e1177da2f229be04139c27e5370a1cfba52"},{"url":"https://git.kernel.org/stable/c/84ae3cfd7d3a63591a2eb4faa24faf678c6708aa"},{"url":"https://git.kernel.org/stable/c/c7362f6a18ed167f52f08ce25eeec8a7818c5004"},{"url":"https://git.kernel.org/stable/c/8f5b30cc12c409ff62891e47ed51e6bf0945a3ea"},{"url":"https://git.kernel.org/stable/c/005b23d9e324fe5d0acbcfa70c625f2e81189046"},{"url":"https://git.kernel.org/stable/c/46f8ffd0a1f1eb6cbc94946a92c11ef601e228a1"}],"tags":["cve.org"],"ingestedAt":"2026-10-18T15:45:12.304Z","slug":"CVE-2026-98455","body":"## Overview\n\nIn the Linux kernel, the following vulnerability has been resolved:\n\nBluetooth: RFCOMM: fix NULL dereference of dlc->session in RFCOMM_CONNINFO\n\nThe RFCOMM_CONNINFO getsockopt handler accepts a socket that is not\nconnected as long as deferred setup is enabled:\n\n\tif (sk->sk_state != BT_CONNECTED &&\n\t\t\t\t!rfcomm_pi(sk)->dlc->defer_setup) {\n\t\terr = -ENOTCONN;\n\t\tbreak;\n\t}\n\tl2cap_sk = rfcomm_pi(sk)->dlc->session->sock->sk;\n\ndlc->defer_setup is set in rfcomm_sock_init() when rfcomm_connect_ind()\ncreates a child socket for an incoming connection on a listening socket\nthat has BT_DEFER_SETUP enabled. It is never cleared afterwards. The\nsession, however, can go away underneath it.\n\nrfcomm_recv_disc() forces the dlc state before tearing it down:\n\n\td->state = BT_CLOSED;\n\t__rfcomm_dlc_close(d, err);\n\nThe RFCOMM_DEFER_SETUP early return in __rfcomm_dlc_close() only covers\nBT_CONNECT, BT_CONFIG, BT_OPEN and BT_CONNECT2, so with the state\nalready BT_CLOSED that switch does not match and the function falls\nthrough to rfcomm_dlc_unlink(), which sets d->session = NULL, while\nd->defer_setup stays 1.\n\nA getsockopt(SOL_RFCOMM, RFCOMM_CONNINFO) on the accepted socket after\nthat point therefore skips the -ENOTCONN path -- sk->sk_state is\nBT_CLOSED, but dlc->defer_setup is still set -- and dereferences the\nNULL session. No race is needed: once the DISC has been processed, the\ndereference is unconditional.\n\nReproduced on a KASAN kernel under QEMU with a BR/EDR peer emulated over\n/dev/vhci: the peer brings up an ACL link, opens L2CAP on the RFCOMM\nPSM, starts a session and sends SABM for a channel bound with\nBT_DEFER_SETUP, and sends DISC for that dlci after the socket has been\naccepted. getsockopt(SOL_RFCOMM, RFCOMM_CONNINFO) on the accepted\nsocket then hits:\n\n Oops: general protection fault, probably for non-canonical address\n 0xdffffc0000000002: 0000 [#1] SMP KASAN PTI\n KASAN: null-ptr-deref in range [0x0000000000000010-0x0000000000000017]\n CPU: 1 UID: 0 PID: 150 Comm: init Tainted: G B 7.3.0-rc3-g5dd1818b15d9\n Hardware name: QEMU Standard PC (i440FX + PIIX, 1996)\n RIP: 0010:rfcomm_sock_getsockopt+0x529/0x780\n Call Trace:\n  <TASK>\n  do_sock_getsockopt+0x3ad/0x7d0\n  __sys_getsockopt+0x10e/0x1b0\n  __x64_sys_getsockopt+0xc2/0x160\n  do_syscall_64+0xda/0x4b0\n  entry_SYSCALL_64_after_hwframe+0x77/0x7f\n  </TASK>\n\n0x10 is the offset of sock in struct rfcomm_session;\nrfcomm_sock_getsockopt_old() is inlined into rfcomm_sock_getsockopt().\n\nCommit 43a556b2fd43 (\"Bluetooth: RFCOMM: take rfcomm_mutex for the\ndeferred setup accept\") fixed the same \"a remote DISC clears the session\nwhile deferred setup is still flagged\" problem in rfcomm_dlc_accept();\nthis is the remaining instance of it, in the getsockopt path.\n\nDeferred setup only leaves a socket usable here once it has reached\nBT_CONNECT2, so restrict the exception to that state and check that a\nsession is actually present before following it.\n\n## Affected\n\n- `Linux >= bb23c0ab824653be4aa7dfca15b07b3059717004 < c3aee3fc1287c8a555baf3895959087cb0c33fe8`\n- `Linux >= bb23c0ab824653be4aa7dfca15b07b3059717004 < 4bf5ca47203049ce3648f750a53dcdc98bcc9e3e`\n- `Linux >= bb23c0ab824653be4aa7dfca15b07b3059717004 < 1c4f7e1177da2f229be04139c27e5370a1cfba52`\n- `Linux >= bb23c0ab824653be4aa7dfca15b07b3059717004 < 84ae3cfd7d3a63591a2eb4faa24faf678c6708aa`\n- `Linux >= bb23c0ab824653be4aa7dfca15b07b3059717004 < c7362f6a18ed167f52f08ce25eeec8a7818c5004`\n- `Linux >= bb23c0ab824653be4aa7dfca15b07b3059717004 < 8f5b30cc12c409ff62891e47ed51e6bf0945a3ea`\n- `Linux >= bb23c0ab824653be4aa7dfca15b07b3059717004 < 005b23d9e324fe5d0acbcfa70c625f2e81189046`\n- `Linux >= bb23c0ab824653be4aa7dfca15b07b3059717004 < 46f8ffd0a1f1eb6cbc94946a92c11ef601e228a1`\n- `Linux 2.6.30`\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"sunlit","depthScore":3,"depthScoreParts":{"impact":2.8,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}