linux-cve-announce - CVE-2025-38592: Bluetooth: hci_devcd_dump: fix out-of-bounds via dev

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Message-ID: <2025081917-CVE-2025-38592-9905@gregkh>
Date: Tue, 19 Aug 2025 19:18:38 +0200
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...nel.org>
Subject: CVE-2025-38592: Bluetooth: hci_devcd_dump: fix out-of-bounds via dev_coredumpv

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

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

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

Bluetooth: hci_devcd_dump: fix out-of-bounds via dev_coredumpv

Currently both dev_coredumpv and skb_put_data in hci_devcd_dump use
hdev->dump.head. However, dev_coredumpv can free the buffer. From
dev_coredumpm_timeout documentation, which is used by dev_coredumpv:

    > Creates a new device coredump for the given device. If a previous one hasn't
    > been read yet, the new coredump is discarded. The data lifetime is determined
    > by the device coredump framework and when it is no longer needed the @free
    > function will be called to free the data.

If the data has not been read by the userspace yet, dev_coredumpv will
discard new buffer, freeing hdev->dump.head. This leads to
vmalloc-out-of-bounds error when skb_put_data tries to access
hdev->dump.head.

A crash report from syzbot illustrates this:

    ==================================================================
    BUG: KASAN: vmalloc-out-of-bounds in skb_put_data
    include/linux/skbuff.h:2752 [inline]
    BUG: KASAN: vmalloc-out-of-bounds in hci_devcd_dump+0x142/0x240
    net/bluetooth/coredump.c:258
    Read of size 140 at addr ffffc90004ed5000 by task kworker/u9:2/5844

    CPU: 1 UID: 0 PID: 5844 Comm: kworker/u9:2 Not tainted
    6.14.0-syzkaller-10892-g4e82c87058f4 #0 PREEMPT(full)
    Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
    Google 02/12/2025
    Workqueue: hci0 hci_devcd_timeout
    Call Trace:
     <TASK>
     __dump_stack lib/dump_stack.c:94 [inline]
     dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120
     print_address_description mm/kasan/report.c:408 [inline]
     print_report+0xc3/0x670 mm/kasan/report.c:521
     kasan_report+0xe0/0x110 mm/kasan/report.c:634
     check_region_inline mm/kasan/generic.c:183 [inline]
     kasan_check_range+0xef/0x1a0 mm/kasan/generic.c:189
     __asan_memcpy+0x23/0x60 mm/kasan/shadow.c:105
     skb_put_data include/linux/skbuff.h:2752 [inline]
     hci_devcd_dump+0x142/0x240 net/bluetooth/coredump.c:258
     hci_devcd_timeout+0xb5/0x2e0 net/bluetooth/coredump.c:413
     process_one_work+0x9cc/0x1b70 kernel/workqueue.c:3238
     process_scheduled_works kernel/workqueue.c:3319 [inline]
     worker_thread+0x6c8/0xf10 kernel/workqueue.c:3400
     kthread+0x3c2/0x780 kernel/kthread.c:464
     ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:153
     ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
     </TASK>

    The buggy address ffffc90004ed5000 belongs to a vmalloc virtual mapping
    Memory state around the buggy address:
     ffffc90004ed4f00: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
     ffffc90004ed4f80: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
    >ffffc90004ed5000: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
                       ^
     ffffc90004ed5080: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
     ffffc90004ed5100: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
    ==================================================================

To avoid this issue, reorder dev_coredumpv to be called after
skb_put_data that does not free the data.

The Linux kernel CVE team has assigned CVE-2025-38592 to this issue.


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

	Issue introduced in 6.15 with commit b257e02ecc46f8561d8bd88943164a10c9e90a80 and fixed in 6.15.10 with commit efd55f6a59449f8d4e4953f12c177aa902b7451f
	Issue introduced in 6.15 with commit b257e02ecc46f8561d8bd88943164a10c9e90a80 and fixed in 6.16.1 with commit 8c021ad797f9171d015cf0a932a3fbe5232190f5
	Issue introduced in 6.15 with commit b257e02ecc46f8561d8bd88943164a10c9e90a80 and fixed in 6.17-rc1 with commit 7af4d7b53502286c6cf946d397ab183e76d14820

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-2025-38592
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/bluetooth/coredump.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/efd55f6a59449f8d4e4953f12c177aa902b7451f
	https://git.kernel.org/stable/c/8c021ad797f9171d015cf0a932a3fbe5232190f5
	https://git.kernel.org/stable/c/7af4d7b53502286c6cf946d397ab183e76d14820