CVE ID : CVE-2024-56549
Published : Dec. 27, 2024, 2:15 p.m. | 1 hour ago
Description : 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.
Severity: 0.0 | NA
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