In the Linux kernel, the following vulnerability has been resolved: wifi: ath10k: snoc: use memcpy_fromio() for MSA ramdump On WCN3990/SNO

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

wifi: ath10k: snoc: use memcpy_fromio() for MSA ramdump

On WCN3990/SNOC the MSA region is mapped with devm_memremap(MEMREMAP_WT).
On arm64 such a mapping is not Normal-cacheable, so unaligned accesses to
it are not permitted. ath10k_msa_dump_memory() copies the region with a
plain memcpy(), whose optimized __pi_memcpy_generic implementation issues
wide/unaligned loads. This triggers an alignment fault (FSC=0x21) Oops in
ath10k_snoc_fw_crashed_dump() while collecting the devcoredump:

Unable to handle kernel paging request ... FSC=0x21: alignment fault
pc : __pi_memcpy_generic
lr : ath10k_snoc_fw_crashed_dump [ath10k_snoc]

The Oops both leaves the firmware RAM dump buffer zeroed (no dump is
captured) and crashes the kernel, which in turn breaks modem SSR
recovery.

Use memcpy_fromio(), which only performs accesses that are valid for such
a device-memory mapping. The generic memcpy_fromio() implementation aligns
the source before issuing word-sized reads and stores the destination with
put_unaligned(), so it is also safe for the coherent DMA allocation used on
the non-reserved-memory path. ath11k and ath12k use the same pattern
when copying target memory into crash dumps, so call it unconditionally
here too.
The MEMREMAP_WT pointer is a plain void *, so an explicit __iomem cast is
needed; use __force to keep sparse happy.

Tested-on: WCN3990 hw1.0 SNOC WLAN.HL.3.3.7.c5-00107-QCAHLSWMTPL-1