CVE-2024-56549: cachefiles: Fix NULL pointer dereference in object->file
First published: Fri Dec 27 2024(Updated: )
In the Linux kernel, the following vulnerability has been resolved: cachefiles: Fix NULL pointer dereference in object->file At present, the object->file has the NULL pointer dereference problem in ondemand-mode. The root cause is that the allocated fd and object->file lifetime are inconsistent, and the user-space invocation to anon_fd uses object->file. Following is the process that triggers the issue: [write fd] [umount] cachefiles_ondemand_fd_write_iter fscache_cookie_state_machine cachefiles_withdraw_cookie if (!file) return -ENOBUFS cachefiles_clean_up_object cachefiles_unmark_inode_in_use fput(object->file) object->file = NULL // file NULL pointer dereference! __cachefiles_write(..., file, ...) Fix this issue by add an additional reference count to the object->file before write/llseek, and decrement after it finished.
Credit: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
| Affected Software | Affected Version | How to fix |
|---|---|---|
| Linux Kernel | >=5.19<6.11.11 | |
| Linux Kernel | >=6.12<6.12.2 | |
| debian/linux | 5.10.223-1 5.10.234-1 6.1.129-1 6.1.133-1 6.12.22-1 | |
| debian/linux-6.1 | 6.1.129-1~deb11u1 |
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Reference Links
- https://git.kernel.org/stable/c/785408bbafcfa24c9fc5b251f03fd0780ce182bd
- https://git.kernel.org/stable/c/f98770440c9bc468e2fd878212ec9526dbe08293
- https://git.kernel.org/stable/c/9582c7664103c9043e80a78f5c382aa6bdd67418
- https://git.kernel.org/stable/c/31ad74b20227ce6b40910ff78b1c604e42975cf1
- https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2024-56549
- https://nvd.nist.gov/vuln/detail/CVE-2024-56549
- https://launchpad.net/bugs/cve/CVE-2024-56549
- https://security-tracker.debian.org/tracker/CVE-2024-56549
- https://ubuntu.com/security/CVE-2024-56549
- https://git.kernel.org/linus/31ad74b20227ce6b40910ff78b1c604e42975cf1
- https://git.kernel.org/stable/c/d6bba3ece960129a553d4b16f1b00c884dc0993a
Frequently Asked Questions
What is the severity of CVE-2024-56549?
CVE-2024-56549 has a high severity due to the potential for a NULL pointer dereference in the Linux kernel.
How do I fix CVE-2024-56549?
To fix CVE-2024-56549, upgrade to the appropriate patched versions of the Linux kernel mentioned in security advisories.
What versions of the Linux kernel are affected by CVE-2024-56549?
CVE-2024-56549 affects Linux kernel versions from 5.19 up to 6.11.11 and also versions from 6.12 to 6.12.2.
What are the consequences of exploiting CVE-2024-56549?
Exploitation of CVE-2024-56549 could lead to system crashes or instability due to the NULL pointer dereference.
Is CVE-2024-56549 a local or remote vulnerability?
CVE-2024-56549 is considered a local vulnerability as it requires local access to exploit the NULL pointer dereference.
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