{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2026-80819", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-08-26T14:34:25.795Z", "datePublished": "2026-09-04T15:13:40.309Z", "dateUpdated": "2026-10-19T08:44:12.945Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-10-19T08:44:12.945Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nBluetooth: RFCOMM: take rfcomm_mutex for the deferred setup accept\n\nrfcomm_sock_recvmsg() completes a deferred setup by calling\nrfcomm_dlc_accept() without holding any RFCOMM lock:\n\n\tif (test_and_clear_bit(RFCOMM_DEFER_SETUP, &d->flags)) {\n\t\trfcomm_dlc_accept(d);\n\t\treturn 0;\n\t}\n\nand rfcomm_dlc_accept() dereferences the session on its first line:\n\n\tstruct sock *sk = d->session->sock->sk;\n\nEvery other path that touches d->session runs under rfcomm_mutex:\nrfcomm_dlc_open(), rfcomm_dlc_close(), rfcomm_dlc_exists(),\nrfcomm_dlc_send_rpn(), and the RFCOMM thread through\nrfcomm_process_sessions(). rfcomm_connect_ind() is even documented as\n\"called under rfcomm_lock()\". This call site is the only one that skips\nit.\n\nThe RFCOMM_DEFER_SETUP bit looks like it serialises the accept against\nteardown, since __rfcomm_dlc_close() returns early when it wins the\ntest_and_clear. But rfcomm_recv_disc() forces the state first:\n\n\td->state = BT_CLOSED;\n\t__rfcomm_dlc_close(d, err);\n\nand the early return only covers BT_CONNECT, BT_CONFIG, BT_OPEN and\nBT_CONNECT2. With the state already BT_CLOSED that switch does not\nmatch, the bit is never consulted, and __rfcomm_dlc_close() falls\nthrough to rfcomm_dlc_unlink(), which sets d->session = NULL.\n\nSo a remote DISC on a deferred dlc clears the session while leaving\nRFCOMM_DEFER_SETUP set. The next recvmsg() then passes the\ntest_and_clear and dereferences a NULL session. No timing window is\nneeded: once the DISC has been processed, the dereference is\nunconditional.\n\nGive rfcomm_dlc_accept() the same shape as rfcomm_dlc_open() and\nrfcomm_dlc_close(): an exported wrapper that takes rfcomm_mutex and\nre-checks the session, around a __rfcomm_dlc_accept() that the two\nin-core callers, which already hold the mutex, keep using.\n\nReproduced on a KASAN + PROVE_LOCKING kernel with a BR/EDR peer emulated\nover /dev/vhci: the peer brings up an ACL link, opens L2CAP on the\nRFCOMM PSM, starts a session, opens a dlc on a channel bound with\nBT_DEFER_SETUP, and sends DISC after the socket is accepted. recv() on\nthe accepted socket then hits:\n\n Oops: general protection fault\n KASAN: null-ptr-deref in range [0x0000000000000010-0x0000000000000017]\n RIP: 0010:rfcomm_dlc_accept+0x54/0x350\n Call Trace:\n rfcomm_sock_recvmsg+0x1cd/0x230\n sock_recvmsg+0x166/0x1c0\n __sys_recvfrom+0x20d/0x300\n\n0x10 is the offset of sock in struct rfcomm_session. With this patch the\nsame run completes with recv() returning 0 and no report, and lockdep\nstays quiet, confirming rfcomm_mutex is still taken before lock_sock on\nthis path as it is on the thread side." } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "net/bluetooth/rfcomm/core.c" ], "versions": [ { "version": "bb23c0ab824653be4aa7dfca15b07b3059717004", "lessThan": "d8d686dd5662a7c4745e4515f1237a9f3b7df181", "status": "affected", "versionType": "git" }, { "version": "bb23c0ab824653be4aa7dfca15b07b3059717004", "lessThan": "eb71d5a1ea8ff2683e394b48ae3cd676037ab4c2", "status": "affected", "versionType": "git" }, { "version": "bb23c0ab824653be4aa7dfca15b07b3059717004", "lessThan": "56f0aa75c7640e46397ef73bea251fcbef9150c0", "status": "affected", "versionType": "git" }, { "version": "bb23c0ab824653be4aa7dfca15b07b3059717004", "lessThan": "362726c9c6e56eea4262109183e49868c39ccd3a", "status": "affected", "versionType": "git" }, { "version": "bb23c0ab824653be4aa7dfca15b07b3059717004", "lessThan": "825b95561d7b7c393df9e7bc295451aaeadc3d18", "status": "affected", "versionType": "git" }, { "version": "bb23c0ab824653be4aa7dfca15b07b3059717004", "lessThan": "d4b1a13b1eff2e80925c7368ffdeaaa50cba93df", "status": "affected", "versionType": "git" }, { "version": "bb23c0ab824653be4aa7dfca15b07b3059717004", "lessThan": "355bfd57ca4ca881c6eb03ca813b440a094b1f44", "status": "affected", "versionType": "git" }, { "version": "bb23c0ab824653be4aa7dfca15b07b3059717004", "lessThan": "b405c2f96ae2e37375105881890f7738833b1d62", "status": "affected", "versionType": "git" }, { "version": "bb23c0ab824653be4aa7dfca15b07b3059717004", "lessThan": "43a556b2fd43f2df6dded59c2e26560a27874c24", "status": "affected", "versionType": "git" } ] }, { "product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "net/bluetooth/rfcomm/core.c" ], "versions": [ { "version": "2.6.30", "status": "affected" }, { "version": "0", "lessThan": "2.6.30", "status": "unaffected", "versionType": "semver" }, { "version": "5.10.267", "lessThanOrEqual": "5.10.*", "status": "unaffected", "versionType": "semver" }, { "version": "5.15.218", "lessThanOrEqual": "5.15.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.1.185", "lessThanOrEqual": "6.1.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.6.154", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.12.106", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.18.47", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.1.11", "lessThanOrEqual": "7.1.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.2.1", "lessThanOrEqual": "7.2.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.3", "lessThanOrEqual": "*", "status": "unaffected", "versionType": "original_commit_for_fix" } ] } ], "cpeApplicability": [ { "nodes": [ { "operator": "OR", "negate": false, "cpeMatch": [ { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.30", "versionEndExcluding": "5.10.267" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.30", "versionEndExcluding": "5.15.218" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.30", "versionEndExcluding": "6.1.185" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.30", "versionEndExcluding": "6.6.154" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.30", "versionEndExcluding": "6.12.106" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.30", "versionEndExcluding": "6.18.47" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.30", "versionEndExcluding": "7.1.11" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.30", "versionEndExcluding": "7.2.1" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.30", "versionEndExcluding": "7.3" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/d8d686dd5662a7c4745e4515f1237a9f3b7df181" }, { "url": "https://git.kernel.org/stable/c/eb71d5a1ea8ff2683e394b48ae3cd676037ab4c2" }, { "url": "https://git.kernel.org/stable/c/56f0aa75c7640e46397ef73bea251fcbef9150c0" }, { "url": "https://git.kernel.org/stable/c/362726c9c6e56eea4262109183e49868c39ccd3a" }, { "url": "https://git.kernel.org/stable/c/825b95561d7b7c393df9e7bc295451aaeadc3d18" }, { "url": "https://git.kernel.org/stable/c/d4b1a13b1eff2e80925c7368ffdeaaa50cba93df" }, { "url": "https://git.kernel.org/stable/c/355bfd57ca4ca881c6eb03ca813b440a094b1f44" }, { "url": "https://git.kernel.org/stable/c/b405c2f96ae2e37375105881890f7738833b1d62" }, { "url": "https://git.kernel.org/stable/c/43a556b2fd43f2df6dded59c2e26560a27874c24" } ], "title": "Bluetooth: RFCOMM: take rfcomm_mutex for the deferred setup accept", "x_generator": { "engine": "bippy-1.2.0" } } } }