CVE-2025-38592
Unknown Unknown - Not Provided
BaseFortify

Publication date: 2025-08-19

Last updated on: 2025-11-26

Assigner: kernel.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.
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Meta Information
Published
2025-08-19
Last Modified
2025-11-26
Generated
2026-05-07
AI Q&A
2025-08-19
EPSS Evaluated
2026-05-05
NVD
Affected Vendors & Products
Showing 2 associated CPEs
Vendor Product Version / Range
linux linux_kernel From 5.15.160 (inc) to 5.16 (inc)
linux linux_kernel From 5.15.160 (inc) to 5.16 (inc)
Helpful Resources
Exploitability
CWE
CWE Icon
KEV
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CWE ID Description
CWE-125 The product reads data past the end, or before the beginning, of the intended buffer.
Attack-Flow Graph
AI Powered Q&A
Can you explain this vulnerability to me?

This vulnerability is a bug in the Linux kernel's Bluetooth component, specifically in the hci_devcd_dump function. It occurs because two functions, dev_coredumpv and skb_put_data, both use the same buffer (hdev->dump.head). However, dev_coredumpv can free this buffer if the data has not yet been read by userspace, leading to a use-after-free scenario. When skb_put_data then tries to access this freed buffer, it causes a vmalloc-out-of-bounds error, which can crash the system.


How can this vulnerability impact me? :

This vulnerability can cause a system crash due to an out-of-bounds memory access in the Bluetooth subsystem of the Linux kernel. This can lead to denial of service (DoS) by crashing the kernel, potentially disrupting normal operation of the affected system.


How can this vulnerability be detected on my network or system? Can you suggest some commands?

This vulnerability can be detected by monitoring for kernel crash reports or logs indicating a vmalloc-out-of-bounds error related to Bluetooth's hci_devcd_dump function. Specifically, look for KASAN (Kernel Address Sanitizer) reports showing vmalloc-out-of-bounds in skb_put_data or hci_devcd_dump. Commands to check kernel logs include: `dmesg | grep -i 'vmalloc-out-of-bounds'` or `journalctl -k | grep -i 'hci_devcd_dump'`. Additionally, enabling KASAN in the kernel can help detect such memory errors during testing.


What immediate steps should I take to mitigate this vulnerability?

To mitigate this vulnerability, update the Linux kernel to a version where the issue is fixed by reordering the dev_coredumpv call to occur after skb_put_data, preventing the out-of-bounds access. If an immediate kernel update is not possible, consider disabling Bluetooth device coredump functionality temporarily to avoid triggering the vulnerable code path.


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