In the Linux kernel, the following vulnerability has been resolved:
platform/x86/amd/pmc: Propagate SMU errors and validate S2D address
amd_stb_s2d_init() discards the return value of several S2D SMU commands.
When the SMU refuses a command (e.g. “SMU cmd failed. err: 0xff”) the
failure is only noticed indirectly – if at all – and reported as -EIO,
masking the real error.
More seriously, the S2D_PHYS_ADDR_LOW/HIGH return values are ignored, so
on failure phys_addr_low/hi are left uninitialised and the assembled
address is passed straight to devm_ioremap(). When the SMU leaves them at
zero this maps physical address 0 and trips the ioremap-on-RAM warning:
amd_pmc AMDI000B:00: SMU cmd failed. err: 0xff
ioremap on RAM at 0x0000000000000000 – 0x0000000000ffffff
WARNING: CPU: 13 PID: 4592 at arch/x86/mm/ioremap.c:…
Check the return value of each SMU command and propagate it, and reject a
zero physical address before calling devm_ioremap().
