Ubuntu: (CVE-2022-49890): linux vulnerability

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

capabilities: fix potential memleak on error path from vfs_getxattr_alloc()

In cap_inode_getsecurity(), we will use vfs_getxattr_alloc() to
complete the memory allocation of tmpbuf, if we have completed
the memory allocation of tmpbuf, but failed to call handler->get(...),
there will be a memleak in below logic:

|-- ret = (int)vfs_getxattr_alloc(mnt_userns, ...)
| /* ^^^ alloc for tmpbuf */
|-- value = krealloc(*xattr_value, error + 1, flags)
| /* ^^^ alloc memory */
|-- error = handler->get(handler, ...)
| /* error! */
|-- *xattr_value = value
| /* xattr_value is &tmpbuf (memory leak!) */

So we will try to free(tmpbuf) after vfs_getxattr_alloc() fails to fix it.

[PM: subject line and backtrace tweaks]