CVE-2022-50765

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

RISC-V: kexec: Fix memory leak of elf header buffer

This is reported by kmemleak detector:

unreferenced object 0xff2000000403d000 (size 4096): comm "kexec", pid 146, jiffies 4294900633 (age 64.792s) hex dump (first 32 bytes): 7f 45 4c 46 02 01 01 00 00 00 00 00 00 00 00 00 .ELF............ 04 00 f3 00 01 00 00 00 00 00 00 00 00 00 00 00 ................ backtrace: [<00000000566ca97c>] kmemleak_vmalloc+0x3c/0xbe [<00000000979283d8>] __vmallocnoderange+0x3ac/0x560 [<00000000b4b3712a>] __vmallocnode+0x56/0x62 [<00000000854f75e2>] vzalloc+0x2c/0x34 [<00000000e9a00db9>] crashprepareelf64headers+0x80/0x30c [<0000000067e8bf48>] elfkexecload+0x3e8/0x4ec [<0000000036548e09>] kexecimageloaddefault+0x40/0x4c [<0000000079fbe1b4>] syskexecfileload+0x1c4/0x322 [<0000000040c62c03>] retfromsyscall+0x0/0x2

In elfkexecload(), a buffer is allocated via vzalloc() to store elf headers. While it's not freed back to system when kdump kernel is reloaded or unloaded, or when image->elfheader is successfully set and then fails to load kdump kernel for some reason. Fix it by freeing the buffer in archkimagefilepostloadcleanup().