Bluetooth: l2cap: fix null-ptr-deref in l2cap_chan_timeout
There is a race condition between l2cap_chan_timeout() and
l2cap_chan_del(). When we use l2cap_chan_del() to delete the
channel, the chan->conn will be set to null. But the conn could
be dereferenced again in the mutex_lock() of l2cap_chan_timeout().
As a result the null pointer dereference bug will happen. The
KASAN report triggered by POC is shown below:
[ 472.074580] ==================================================================
[ 472.075284] BUG: KASAN: null-ptr-deref in mutex_lock+0x68/0xc0
[ 472.075308] Write of size 8 at addr 0000000000000158 by task kworker/0:0/7
[ 472.075308]
[ 472.075308] CPU: 0 PID: 7 Comm: kworker/0:0 Not tainted 6.9.0-rc5-00356-g78c0094a146b #36
[ 472.075308] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.14.0-0-g155821a1990b-prebuilt.qemu4
[ 472.075308] Workqueue: events l2cap_chan_timeout
[ 472.075308] Call Trace:
[ 472.075308] <TASK>
[ 472.075308] dump_stack_lvl+0x137/0x1a0
[ 472.075308] print_report+0x101/0x250
[ 472.075308] ? __virt_addr_valid+0x77/0x160
[ 472.075308] ? mutex_lock+0x68/0xc0
[ 472.075308] kasan_report+0x139/0x170
[ 472.075308] ? mutex_lock+0x68/0xc0
[ 472.075308] kasan_check_range+0x2c3/0x2e0
[ 472.075308] mutex_lock+0x68/0xc0
[ 472.075308] l2cap_chan_timeout+0x181/0x300
[ 472.075308] process_one_work+0x5d2/0xe00
[ 472.075308] worker_thread+0xe1d/0x1660
[ 472.075308] ? pr_cont_work+0x5e0/0x5e0
[ 472.075308] kthread+0x2b7/0x350
[ 472.075308] ? pr_cont_work+0x5e0/0x5e0
[ 472.075308] ? kthread_blkcg+0xd0/0xd0
[ 472.075308] ret_from_fork+0x4d/0x80
[ 472.075308] ? kthread_blkcg+0xd0/0xd0
[ 472.075308] ret_from_fork_asm+0x11/0x20
[ 472.075308] </TASK>
[ 472.075308] ==================================================================
[ 472.094860] Disabling lock debugging due to kernel taint
[ 472.096136] BUG: kernel NULL pointer dereference, address: 0000000000000158
[ 472.096136] #PF: supervisor write access in kernel mode
[ 472.096136] #PF: error_code(0x0002) - not-present page
[ 472.096136] PGD 0 P4D 0
[ 472.096136] Oops: 0002 [#1] PREEMPT SMP KASAN NOPTI
[ 472.096136] CPU: 0 PID: 7 Comm: kworker/0:0 Tainted: G B 6.9.0-rc5-00356-g78c0094a146b #36
[ 472.096136] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.14.0-0-g155821a1990b-prebuilt.qemu4
[ 472.096136] Workqueue: events l2cap_chan_timeout
[ 472.096136] RIP: 0010:mutex_lock+0x88/0xc0
[ 472.096136] Code: be 08 00 00 00 e8 f8 23 1f fd 4c 89 f7 be 08 00 00 00 e8 eb 23 1f fd 42 80 3c 23 00 74 08 48 88
[ 472.096136] RSP: 0018:ffff88800744fc78 EFLAGS: 00000246
[ 472.096136] RAX: 0000000000000000 RBX: 1ffff11000e89f8f RCX: ffffffff8457c865
[ 472.096136] RDX: 0000000000000001 RSI: 0000000000000008 RDI: ffff88800744fc78
[ 472.096136] RBP: 0000000000000158 R08: ffff88800744fc7f R09: 1ffff11000e89f8f
[ 472.096136] R10: dffffc0000000000 R11: ffffed1000e89f90 R12: dffffc0000000000
[ 472.096136] R13: 0000000000000158 R14: ffff88800744fc78 R15: ffff888007405a00
[ 472.096136] FS: 0000000000000000(0000) GS:ffff88806d200000(0000) knlGS:0000000000000000
[ 472.096136] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 472.096136] CR2: 0000000000000158 CR3: 000000000da32000 CR4: 00000000000006f0
[ 472.096136] Call Trace:
[ 472.096136] <TASK>
[ 472.096136] ? __die_body+0x8d/0xe0
[ 472.096136] ? page_fault_oops+0x6b8/0x9a0
[ 472.096136] ? kernelmode_fixup_or_oops+0x20c/0x2a0
[ 472.096136] ? do_user_addr_fault+0x1027/0x1340
[ 472.096136] ? _printk+0x7a/0xa0
[ 472.096136] ? mutex_lock+0x68/0xc0
[ 472.096136] ? add_taint+0x42/0xd0
[ 472.096136] ? exc_page_fault+0x6a/0x1b0
[ 472.096136] ? asm_exc_page_fault+0x26/0x30
[ 472.096136] ? mutex_lock+0x75/0xc0
[ 472.096136] ? mutex_lock+0x88/0xc0
[ 472.096136] ? mutex_lock+0x75/0xc0
[ 472.096136] l2cap_chan_timeo
---truncated---
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Tracking
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| Source | ID | Title |
|---|---|---|
Debian DLA |
DLA-3840-1 | linux security update |
Debian DLA |
DLA-3843-1 | linux-5.10 security update |
Debian DSA |
DSA-5703-1 | linux security update |
Ubuntu USN |
USN-6949-1 | Linux kernel vulnerabilities |
Ubuntu USN |
USN-6949-2 | Linux kernel vulnerabilities |
Ubuntu USN |
USN-6950-1 | Linux kernel vulnerabilities |
Ubuntu USN |
USN-6950-2 | Linux kernel vulnerabilities |
Ubuntu USN |
USN-6950-3 | Linux kernel (Oracle) vulnerabilities |
Ubuntu USN |
USN-6950-4 | Linux kernel (HWE) vulnerabilities |
Ubuntu USN |
USN-6951-1 | Linux kernel vulnerabilities |
Ubuntu USN |
USN-6951-2 | Linux kernel (Azure) vulnerabilities |
Ubuntu USN |
USN-6951-3 | Linux kernel (Azure) vulnerabilities |
Ubuntu USN |
USN-6951-4 | Linux kernel (BlueField) vulnerabilities |
Ubuntu USN |
USN-6952-1 | Linux kernel vulnerabilities |
Ubuntu USN |
USN-6953-1 | Linux kernel (Oracle) vulnerabilities |
Ubuntu USN |
USN-6955-1 | Linux kernel (OEM) vulnerabilities |
Ubuntu USN |
USN-6956-1 | Linux kernel (Azure) vulnerabilities |
Ubuntu USN |
USN-6957-1 | Linux kernel (Oracle) vulnerabilities |
Ubuntu USN |
USN-6979-1 | Linux kernel (Raspberry Pi) vulnerabilities |
Ubuntu USN |
USN-7019-1 | Linux kernel vulnerabilities |
Thu, 22 Jan 2026 23:00:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| First Time appeared |
Debian
Debian debian Linux Fedoraproject Fedoraproject fedora Linux Linux linux Kernel |
|
| Weaknesses | CWE-476 | |
| CPEs | cpe:2.3:o:debian:debian_linux:10.0:*:*:*:*:*:*:* cpe:2.3:o:fedoraproject:fedora:39:*:*:*:*:*:*:* cpe:2.3:o:fedoraproject:fedora:40:*:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:6.9:rc1:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:6.9:rc2:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:6.9:rc3:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:6.9:rc4:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:6.9:rc5:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:6.9:rc6:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:6.9:rc7:*:*:*:*:*:* |
|
| Vendors & Products |
Debian
Debian debian Linux Fedoraproject Fedoraproject fedora Linux Linux linux Kernel |
Thu, 19 Dec 2024 15:00:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| CPEs | cpe:/a:redhat:enterprise_linux:9 cpe:/o:redhat:enterprise_linux:9 |
Wed, 04 Dec 2024 15:00:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| CPEs | cpe:/a:redhat:rhel_eus:9.2 cpe:/a:redhat:rhel_eus:9.2::nfv cpe:/a:redhat:rhel_eus:9.4 |
Wed, 27 Nov 2024 02:45:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| First Time appeared |
Redhat enterprise Linux
|
|
| CPEs | cpe:/o:redhat:enterprise_linux:8 | |
| Vendors & Products |
Redhat enterprise Linux
|
Fri, 22 Nov 2024 12:00:00 +0000
Tue, 05 Nov 2024 10:45:00 +0000
Thu, 26 Sep 2024 15:30:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Metrics |
ssvc
|
Tue, 24 Sep 2024 11:15:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| First Time appeared |
Redhat
Redhat rhel Eus |
|
| CPEs | cpe:/o:redhat:rhel_eus:8.8 | |
| Vendors & Products |
Redhat
Redhat rhel Eus |
Status: PUBLISHED
Assigner: Linux
Published:
Updated: 2026-05-11T20:10:16.347Z
Reserved: 2024-02-25T13:47:42.681Z
Link: CVE-2024-27399
Updated: 2024-09-26T15:03:06.207Z
Status : Analyzed
Published: 2024-05-14T15:12:28.977
Modified: 2026-01-22T20:37:12.617
Link: CVE-2024-27399
OpenCVE Enrichment
No data.
Debian DLA
Debian DSA
Ubuntu USN