linux-cve-announce - CVE-2025-38245: atm: Release atm_dev_mutex after removing procfs in atm_dev

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Message-ID: <2025070933-CVE-2025-38245-a430@gregkh>
Date: Wed,  9 Jul 2025 12:42:37 +0200
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...nel.org>
Subject: CVE-2025-38245: atm: Release atm_dev_mutex after removing procfs in atm_dev_deregister().

From: Greg Kroah-Hartman <gregkh@...nel.org>

Description
===========

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

atm: Release atm_dev_mutex after removing procfs in atm_dev_deregister().

syzbot reported a warning below during atm_dev_register(). [0]

Before creating a new device and procfs/sysfs for it, atm_dev_register()
looks up a duplicated device by __atm_dev_lookup().  These operations are
done under atm_dev_mutex.

However, when removing a device in atm_dev_deregister(), it releases the
mutex just after removing the device from the list that __atm_dev_lookup()
iterates over.

So, there will be a small race window where the device does not exist on
the device list but procfs/sysfs are still not removed, triggering the
splat.

Let's hold the mutex until procfs/sysfs are removed in
atm_dev_deregister().

[0]:
proc_dir_entry 'atm/atmtcp:0' already registered
WARNING: CPU: 0 PID: 5919 at fs/proc/generic.c:377 proc_register+0x455/0x5f0 fs/proc/generic.c:377
Modules linked in:
CPU: 0 UID: 0 PID: 5919 Comm: syz-executor284 Not tainted 6.16.0-rc2-syzkaller-00047-g52da431bf03b #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
RIP: 0010:proc_register+0x455/0x5f0 fs/proc/generic.c:377
Code: 48 89 f9 48 c1 e9 03 80 3c 01 00 0f 85 a2 01 00 00 48 8b 44 24 10 48 c7 c7 20 c0 c2 8b 48 8b b0 d8 00 00 00 e8 0c 02 1c ff 90 <0f> 0b 90 90 48 c7 c7 80 f2 82 8e e8 0b de 23 09 48 8b 4c 24 28 48
RSP: 0018:ffffc9000466fa30 EFLAGS: 00010282
RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffffffff817ae248
RDX: ffff888026280000 RSI: ffffffff817ae255 RDI: 0000000000000001
RBP: ffff8880232bed48 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000001 R12: ffff888076ed2140
R13: dffffc0000000000 R14: ffff888078a61340 R15: ffffed100edda444
FS:  00007f38b3b0c6c0(0000) GS:ffff888124753000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f38b3bdf953 CR3: 0000000076d58000 CR4: 00000000003526f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 proc_create_data+0xbe/0x110 fs/proc/generic.c:585
 atm_proc_dev_register+0x112/0x1e0 net/atm/proc.c:361
 atm_dev_register+0x46d/0x890 net/atm/resources.c:113
 atmtcp_create+0x77/0x210 drivers/atm/atmtcp.c:369
 atmtcp_attach drivers/atm/atmtcp.c:403 [inline]
 atmtcp_ioctl+0x2f9/0xd60 drivers/atm/atmtcp.c:464
 do_vcc_ioctl+0x12c/0x930 net/atm/ioctl.c:159
 sock_do_ioctl+0x115/0x280 net/socket.c:1190
 sock_ioctl+0x227/0x6b0 net/socket.c:1311
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:907 [inline]
 __se_sys_ioctl fs/ioctl.c:893 [inline]
 __x64_sys_ioctl+0x18b/0x210 fs/ioctl.c:893
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xcd/0x4c0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f38b3b74459
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 51 18 00 00 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f38b3b0c198 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f38b3bfe318 RCX: 00007f38b3b74459
RDX: 0000000000000000 RSI: 0000000000006180 RDI: 0000000000000005
RBP: 00007f38b3bfe310 R08: 65732f636f72702f R09: 65732f636f72702f
R10: 65732f636f72702f R11: 0000000000000246 R12: 00007f38b3bcb0ac
R13: 00007f38b3b0c1a0 R14: 0000200000000200 R15: 00007f38b3bcb03b
 </TASK>

The Linux kernel CVE team has assigned CVE-2025-38245 to this issue.


Affected and fixed versions
===========================

	Issue introduced in 2.6.15 with commit 64bf69ddff7637b7ed7acf9b2a823cc0ee519439 and fixed in 6.1.143 with commit b2e40fcfe1575faaa548f87614006d3fe44c779e
	Issue introduced in 2.6.15 with commit 64bf69ddff7637b7ed7acf9b2a823cc0ee519439 and fixed in 6.6.96 with commit cabed6ba92a9a8c09da02a3f20e32ecd80989896
	Issue introduced in 2.6.15 with commit 64bf69ddff7637b7ed7acf9b2a823cc0ee519439 and fixed in 6.12.36 with commit ae539d963a17443ec54cba8a767e4ffa318264f4
	Issue introduced in 2.6.15 with commit 64bf69ddff7637b7ed7acf9b2a823cc0ee519439 and fixed in 6.15.5 with commit 6922f1a048c090f10704bbef4a3a1e81932d2e0a
	Issue introduced in 2.6.15 with commit 64bf69ddff7637b7ed7acf9b2a823cc0ee519439 and fixed in 6.16-rc4 with commit a433791aeaea6e84df709e0b9584b9bbe040cd1c

Please see https://www.kernel.org for a full list of currently supported
kernel versions by the kernel community.

Unaffected versions might change over time as fixes are backported to
older supported kernel versions.  The official CVE entry at
	https://cve.org/CVERecord/?id=CVE-2025-38245
will be updated if fixes are backported, please check that for the most
up to date information about this issue.


Affected files
==============

The file(s) affected by this issue are:
	net/atm/resources.c


Mitigation
==========

The Linux kernel CVE team recommends that you update to the latest
stable kernel version for this, and many other bugfixes.  Individual
changes are never tested alone, but rather are part of a larger kernel
release.  Cherry-picking individual commits is not recommended or
supported by the Linux kernel community at all.  If however, updating to
the latest release is impossible, the individual changes to resolve this
issue can be found at these commits:
	https://git.kernel.org/stable/c/b2e40fcfe1575faaa548f87614006d3fe44c779e
	https://git.kernel.org/stable/c/cabed6ba92a9a8c09da02a3f20e32ecd80989896
	https://git.kernel.org/stable/c/ae539d963a17443ec54cba8a767e4ffa318264f4
	https://git.kernel.org/stable/c/6922f1a048c090f10704bbef4a3a1e81932d2e0a
	https://git.kernel.org/stable/c/a433791aeaea6e84df709e0b9584b9bbe040cd1c