cve/2024/CVE-2024-56549.md

### [CVE-2024-56549](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2024-56549)
![](https://img.shields.io/static/v1?label=Product&message=Linux&color=blue)
![](https://img.shields.io/static/v1?label=Version&message=c8383054506c77b814489c09877b5db83fd4abf2%3C%20d6bba3ece960129a553d4b16f1b00c884dc0993a%20&color=brighgreen)
![](https://img.shields.io/static/v1?label=Vulnerability&message=n%2Fa&color=brighgreen)

### Description

In the Linux kernel, the following vulnerability has been resolved:cachefiles: Fix NULL pointer dereference in object->fileAt present, the object->file has the NULL pointer dereference problem inondemand-mode. The root cause is that the allocated fd and object->filelifetime are inconsistent, and the user-space invocation to anon_fd usesobject->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->filebefore write/llseek, and decrement after it finished.

### POC

#### Reference
No PoCs from references.

#### Github
- https://github.com/cku-heise/euvd-api-doc