# CVE-2025-39887: linux: In the Linux kernel, the following vulnerability has been resolved:  tracing/osnoise: Fix null-ptr-deref in bitmap_pa...

CVE-2025-39887 is fixed in linux on 1 platform by DEBIAN-CVE-2025-39887 (version 6.16.8-1), released September 23, 2025. It is not reported as exploited. Patch Radar priority: Routine.

- Web page: https://patchblox.com/security/cve/CVE-2025-39887
- Priority: Routine
- CVSS: 5.5 (medium)
- EPSS: 0.0013
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Sep 23, 2025

## Description

In the Linux kernel, the following vulnerability has been resolved:  tracing/osnoise: Fix null-ptr-deref in bitmap_parselist()  A crash was observed with the following output:  BUG: kernel NULL pointer dereference, address: 0000000000000010 Oops: Oops: 0000 [#1] SMP NOPTI CPU: 2 UID: 0 PID: 92 Comm: osnoise_cpus Not tainted 6.17.0-rc4-00201-gd69eb204c255 #138 PREEMPT(voluntary) RIP: 0010:bitmap_parselist+0x53/0x3e0 Call Trace:  <TASK>  osnoise_cpus_write+0x7a/0x190  vfs_write+0xf8/0x410  ? do_sys_openat2+0x88/0xd0  ksys_write+0x60/0xd0  do_syscall_64+0xa4/0x260  entry_SYSCALL_64_after_hwframe+0x77/0x7f  </TASK>  This issue can be reproduced by below code:  fd=open("/sys/kernel/debug/tracing/osnoise/cpus", O_WRONLY); write(fd, "0-2", 0);  When user pass 'count=0' to osnoise_cpus_write(), kmalloc() will return ZERO_SIZE_PTR (16) and cpulist_parse() treat it as a normal value, which trigger the null pointer dereference. Add check for the parameter 'count'.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | linux Debian 14 | 6.16.8-1 | [DEBIAN-CVE-2025-39887](https://patchblox.com/security/data/fix/linux/debian-cve-2025-39887.md) | Sep 23, 2025 |

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