CVE-2024-47709

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:

<TASK>

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

</TASK>