Description
In the Linux kernel, the following vulnerability has been resolved: Bluetooth: Fix null-ptr-deref in l2cap_sock_resume_cb() syzbot reported null-ptr-deref in l2cap_sock_resume_cb(). [0] l2cap_sock_resume_cb() has a similar problem that was fixed by commit 1bff51ea59a9 ("Bluetooth: fix use-after-free error in lock_sock_nested()"). Since both l2cap_sock_kill() and l2cap_sock_resume_cb() are executed under l2cap_sock_resume_cb(), we can avoid the issue simply by checking if chan->data is NULL. Let's not access to the killed socket in l2cap_sock_resume_cb(). [0]: BUG: KASAN: null-ptr-deref in instrument_atomic_write include/linux/instrumented.h:82 [inline] BUG: KASAN: null-ptr-deref in clear_bit include/asm-generic/bitops/instrumented-atomic.h:41 [inline] BUG: KASAN: null-ptr-deref in l2cap_sock_resume_cb+0xb4/0x17c net/bluetooth/l2cap_sock.c:1711 Write of size 8 at addr 0000000000000570 by task kworker/u9:0/52 CPU: 1 UID: 0 PID: 52 Comm: kworker/u9:0 Not tainted 6.16.0-rc4-syzkaller-g7482bb149b9f #0 PREEMPT Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025 Workqueue: hci0 hci_rx_work Call trace: show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:501 (C) __dump_stack+0x30/0x40 lib/dump_stack.c:94 dump_stack_lvl+0xd8/0x12c lib/dump_stack.c:120 print_report+0x58/0x84 mm/kasan/report.c:524 kasan_report+0xb0/0x110 mm/kasan/report.c:634 check_region_inline mm/kasan/generic.c:-1 [inline] kasan_check_range+0x264/0x2a4 mm/kasan/generic.c:189 __kasan_check_write+0x20/0x30 mm/kasan/shadow.c:37 instrument_atomic_write include/linux/instrumented.h:82 [inline] clear_bit include/asm-generic/bitops/instrumented-atomic.h:41 [inline] l2cap_sock_resume_cb+0xb4/0x17c net/bluetooth/l2cap_sock.c:1711 l2cap_security_cfm+0x524/0xea0 net/bluetooth/l2cap_core.c:7357 hci_auth_cfm include/net/bluetooth/hci_core.h:2092 [inline] hci_auth_complete_evt+0x2e8/0xa4c net/bluetooth/hci_event.c:3514 hci_event_func net/bluetooth/hci_event.c:7511 [inline] hci_event_packet+0x650/0xe9c net/bluetooth/hci_event.c:7565 hci_rx_work+0x320/0xb18 net/bluetooth/hci_core.c:4070 process_one_work+0x7e8/0x155c kernel/workqueue.c:3238 process_scheduled_works kernel/workqueue.c:3321 [inline] worker_thread+0x958/0xed8 kernel/workqueue.c:3402 kthread+0x5fc/0x75c kernel/kthread.c:464 ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:847
Product status
d97c899bde330cd1c76c3a162558177563a74362 (git) before 262cd18f5f7ede6a586580cadc5d0799e52e2e7c
d97c899bde330cd1c76c3a162558177563a74362 (git) before 2b27b389006623673e8cfff4ce1e119cce640b05
d97c899bde330cd1c76c3a162558177563a74362 (git) before 3a4eca2a1859955c65f07a570156bd2d9048ce33
d97c899bde330cd1c76c3a162558177563a74362 (git) before ac3a8147bb24314fb3e84986590148e79f9872ec
d97c899bde330cd1c76c3a162558177563a74362 (git) before c4f16f6b071a74ac7eefe5c28985285cbbe2cd96
d97c899bde330cd1c76c3a162558177563a74362 (git) before b97be7ee8a1cd96b89817cbd64a9f5cc16c17d08
d97c899bde330cd1c76c3a162558177563a74362 (git) before 6d63901dcd592a1e3f71d7c6d78f9be5e8d7eef0
d97c899bde330cd1c76c3a162558177563a74362 (git) before a0075accbf0d76c2dad1ad3993d2e944505d99a0
3.13
Any version before 3.13
5.4.297 (semver)
5.10.241 (semver)
5.15.190 (semver)
6.1.147 (semver)
6.6.100 (semver)
6.12.40 (semver)
6.15.8 (semver)
6.16 (original_commit_for_fix)
References
lists.debian.org/debian-lts-announce/2025/10/msg00008.html
lists.debian.org/debian-lts-announce/2025/10/msg00007.html
git.kernel.org/...c/262cd18f5f7ede6a586580cadc5d0799e52e2e7c
git.kernel.org/...c/2b27b389006623673e8cfff4ce1e119cce640b05
git.kernel.org/...c/3a4eca2a1859955c65f07a570156bd2d9048ce33
git.kernel.org/...c/ac3a8147bb24314fb3e84986590148e79f9872ec
git.kernel.org/...c/c4f16f6b071a74ac7eefe5c28985285cbbe2cd96
git.kernel.org/...c/b97be7ee8a1cd96b89817cbd64a9f5cc16c17d08
git.kernel.org/...c/6d63901dcd592a1e3f71d7c6d78f9be5e8d7eef0
git.kernel.org/...c/a0075accbf0d76c2dad1ad3993d2e944505d99a0