Ubuntu: (Multiple Advisories) (CVE-2024-26840): Linux kernel vulnerabilities

In the Linux kernel, the following vulnerability has been resolved:

cachefiles: fix memory leak in cachefiles_add_cache()

The following memory leak was reported after unbinding /dev/cachefiles:

==================================================================
unreferenced object 0xffff9b674176e3c0 (size 192):
comm "cachefilesd2", pid 680, jiffies 4294881224
hex dump (first 32 bytes):
01 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
backtrace (crc ea38a44b):
[] kmem_cache_alloc+0x2d5/0x370
[] prepare_creds+0x26/0x2e0
[] cachefiles_determine_cache_security+0x1f/0x120
[] cachefiles_add_cache+0x13c/0x3a0
[] cachefiles_daemon_write+0x146/0x1c0
[] vfs_write+0xcb/0x520
[] ksys_write+0x69/0xf0
[] do_syscall_64+0x72/0x140
[] entry_SYSCALL_64_after_hwframe+0x6e/0x76
==================================================================

Put the reference count of cache_cred in cachefiles_daemon_unbind() to
fix the problem. And also put cache_cred in cachefiles_add_cache() error
branch to avoid memory leaks.