CVE-2024-50303 — resource,kexec: walk_system_ram_res_rev must retain resource flags

Affected: Linux

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

resource,kexec: walk_system_ram_res_rev must retain resource flags

walk_system_ram_res_rev() erroneously discards resource flags when passing the information to the callback.

This causes systems with IORESOURCE_SYSRAM_DRIVER_MANAGED memory to have these resources selected during kexec to store kexec buffers if that memory happens to be at placed above normal system ram.

This leads to undefined behavior after reboot. If the kexec buffer is never touched, nothing happens. If the kexec buffer is touched, it could lead to a crash (like below) or undefined behavior.

Tested on a system with CXL memory expanders with driver managed memory, TPM enabled, and CONFIG_IMA_KEXEC=y. Adding printk's showed the flags were being discarded and as a result the check for IORESOURCE_SYSRAM_DRIVER_MANAGED passes.

find_next_iomem_res: name(System RAM (kmem)) start(10000000000) end(1034fffffff) flags(83000200)

locate_mem_hole_top_down: start(10000000000) end(1034fffffff) flags(0)

[.] BUG: unable to handle page fault for address: ffff89834ffff000 [.] #PF: supervisor read access in kernel mode [.] #PF: error_code(0x0000) - not-present page [.] PGD c04c8bf067 P4D c04c8bf067 PUD c04c8be067 PMD 0 [.] Oops: 0000 [#1] SMP [.] RIP: 0010:ima_restore_measurement_list+0x95/0x4b0 [.] RSP: 0018:ffffc900000d3a80 EFLAGS: 00010286 [.] RAX: 0000000000001000 RBX: 0000000000000000 RCX: ffff89834ffff000 [.] RDX: 0000000…

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CVE-2024-50303 — resource,kexec: walk_system_ram_res_rev must retain resource flags