Vulnerability Advisory : kernel/kexec: fix IMA when allocation happens in CMA area with undefined Attack Complexity

In the Linux kernel, the following vulnerability has been resolved: kernel/kexec: fix IMA when allocation happens in CMA area *** Bug description *** When I tested kexec with the latest kernel, I ran into the following warning: [ 40.712410] ------------[ cut here ]------------ [ 40.712576] WARNING: CPU: 2 PID: 1562 at kernel/kexec_core.c:1001 kimage_map_segment+0x144/0x198 [...] [ 40.816047] Call trace: [ 40.818498] kimage_map_segment+0x144/0x198 (P) [ 40.823221] ima_kexec_post_load+0x58/0xc0 [ 40.827246] __do_sys_kexec_file_load+0x29c/0x368 [...] [ 40.855423] ---[ end trace 0000000000000000 ]--- *** How to reproduce *** This bug is only triggered when the kexec target address is allocated in the CMA area. If no CMA area is reserved in the kernel, use the "cma=" option in the kernel command line to reserve one. *** Root cause *** The commit 07d24902977e ("kexec: enable CMA based contiguous allocation") allocates the kexec target address directly on the CMA area to avoid copying during the jump. In this case, there is no IND_SOURCE for the kexec segment. But the current implementation of kimage_map_segment() assumes that IND_SOURCE pages exist and map them into a contiguous virtual address by vmap(). *** Solution *** If IMA segment is allocated in the CMA area, use its page_address() directly.