ima: Fix stack-out-of-bounds in is_bprm_creds_for_exec()

Vulnerability Description

In the Linux kernel, the following vulnerability has been resolved: ima: Fix stack-out-of-bounds in is_bprm_creds_for_exec() KASAN reported a stack-out-of-bounds access in ima_appraise_measurement from is_bprm_creds_for_exec: BUG: KASAN: stack-out-of-bounds in ima_appraise_measurement+0x12dc/0x16a0 Read of size 1 at addr ffffc9000160f940 by task sudo/550 The buggy address belongs to stack of task sudo/550 and is located at offset 24 in frame: ima_appraise_measurement+0x0/0x16a0 This frame has 2 objects: [48, 56) 'file' [80, 148) 'hash' This is caused by using container_of on the *file pointer. This offset calculation is what triggers the stack-out-of-bounds error. In order to fix this, pass in a bprm_is_check boolean which can be set depending on how process_measurement is called. If the caller has a linux_binprm pointer and the function is BPRM_CHECK we can determine is_check and set it then. Otherwise set it to false.

References

• https://git.kernel.org/stable/c/ab3d16da982a4ebb715d487dbf9dd66e3990d935
• https://git.kernel.org/stable/c/377cae9851e8559e9d8b82a78c1ac0abeb18839c