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Medium severity5.5NVD Advisory· Published Oct 21, 2024· Updated May 12, 2026

CVE-2024-47709

CVE-2024-47709

Description

In the Linux kernel, the following vulnerability has been resolved:

can: bcm: Clear bo->bcm_proc_read after remove_proc_entry().

syzbot reported a warning in bcm_release(). [0]

The blamed change fixed another warning that is triggered when connect() is issued again for a socket whose connect()ed device has been unregistered.

However, if the socket is just close()d without the 2nd connect(), the remaining bo->bcm_proc_read triggers unnecessary remove_proc_entry() in bcm_release().

Let's clear bo->bcm_proc_read after remove_proc_entry() in bcm_notify().

[0] name '4986' WARNING: CPU: 0 PID: 5234 at fs/proc/generic.c:711 remove_proc_entry+0x2e7/0x5d0 fs/proc/generic.c:711 Modules linked in: CPU: 0 UID: 0 PID: 5234 Comm: syz-executor606 Not tainted 6.11.0-rc5-syzkaller-00178-g5517ae241919 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/06/2024 RIP: 0010:remove_proc_entry+0x2e7/0x5d0 fs/proc/generic.c:711 Code: ff eb 05 e8 cb 1e 5e ff 48 8b 5c 24 10 48 c7 c7 e0 f7 aa 8e e8 2a 38 8e 09 90 48 c7 c7 60 3a 1b 8c 48 89 de e8 da 42 20 ff 90 <0f> 0b 90 90 48 8b 44 24 18 48 c7 44 24 40 0e 36 e0 45 49 c7 04 07 RSP: 0018:ffffc9000345fa20 EFLAGS: 00010246 RAX: 2a2d0aee2eb64600 RBX: ffff888032f1f548 RCX: ffff888029431e00 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000 RBP: ffffc9000345fb08 R08: ffffffff8155b2f2 R09: 1ffff1101710519a R10: dffffc0000000000 R11: ffffed101710519b R12: ffff888011d38640 R13: 0000000000000004 R14: 0000000000000000 R15: dffffc0000000000 FS: 0000000000000000(0000) GS:ffff8880b8800000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007fcfb52722f0 CR3: 000000000e734000 CR4: 00000000003506f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace:

bcm_release+0x250/0x880 net/can/bcm.c:1578 __sock_release net/socket.c:659 [inline] sock_close+0xbc/0x240 net/socket.c:1421 __fput+0x24a/0x8a0 fs/file_table.c:422 task_work_run+0x24f/0x310 kernel/task_work.c:228 exit_task_work include/linux/task_work.h:40 [inline] do_exit+0xa2f/0x27f0 kernel/exit.c:882 do_group_exit+0x207/0x2c0 kernel/exit.c:1031 __do_sys_exit_group kernel/exit.c:1042 [inline] __se_sys_exit_group kernel/exit.c:1040 [inline] __x64_sys_exit_group+0x3f/0x40 kernel/exit.c:1040 x64_sys_call+0x2634/0x2640 arch/x86/include/generated/asm/syscalls_64.h:232 do_syscall_x64 arch/x86/entry/common.c:52 [inline] do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7fcfb51ee969 Code: Unable to access opcode bytes at 0x7fcfb51ee93f. RSP: 002b:00007ffce0109ca8 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 RAX: ffffffffffffffda RBX: 0000000000000001 RCX: 00007fcfb51ee969 RDX: 000000000000003c RSI: 00000000000000e7 RDI: 0000000000000001 RBP: 00007fcfb526f3b0 R08: ffffffffffffffb8 R09: 0000555500000000 R10: 0000555500000000 R11: 0000000000000246 R12: 00007fcfb526f3b0 R13: 0000000000000000 R14: 00007fcfb5271ee0 R15: 00007fcfb51bf160

AI Insight

LLM-synthesized narrative grounded in this CVE's description and references.

A use-after-free vulnerability in the Linux kernel's CAN BCM protocol causes a warning during socket release due to an un-cleared proc entry pointer.

Vulnerability

Overview

A vulnerability in the Linux kernel's CAN Broadcast Manager (BCM) protocol implementation can trigger a warning and potential use-after-free condition during socket release. The root cause is that when a BCM socket's connected network device is removed, the bcm_notify() function removes the associated proc entry (bo->bcm_proc_read) but fails to clear the pointer afterward. If the socket is then closed without reconnecting (connect()), bcm_release() attempts to remove the same proc entry a second time, leading to a warning in remove_proc_entry() and possible memory corruption [1].

Exploitation

Conditions

The vulnerability is exploitable only by a local attacker who can create and close BCM sockets with a device that gets removed. No special privileges are required beyond the ability to open a socket and trigger device removal, but the attacker must be able to control when a device is unregistered. The attack surface is limited to systems that use CAN bus interfaces and where the BCM protocol is enabled [1].

Impact

A successful exploitation leads to a kernel warning and can result in a denial of service (system crash or hang) due to the use-after-free condition. The CVSS v3.1 base score is 5.5 (Medium), with the vector AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H, indicating low attack complexity and high availability impact [1].

Mitigation

The fix is to clear bo->bcm_proc_read after remove_proc_entry() in the bcm_notify() function, ensuring that bcm_release() does not attempt a redundant removal. This patch has been merged into the Linux kernel stable branches, and users should apply the latest updates [1]. Systems that do not use CAN or the BCM protocol are not affected.

References
  1. SSA-355557

AI Insight generated on May 20, 2026. Synthesized from this CVE's description and the cited reference URLs; citations are validated against the source bundle.

Affected products

117

Patches

0

No patches discovered yet.

Vulnerability mechanics

AI mechanics synthesis has not run for this CVE yet.

References

13

News mentions

0

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