CVE-2026-90012

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

spi: Fix DMA mapping ownership on partial map failure

If RX mapping fails after TX mapping succeeds, _spimap_msg() unmaps

TX but leaves txsgmapped set. If TX mapping fails on a later

transfer, mappings created for earlier transfers remain active.

In both cases, cur{tx,rx}dma_dev have not yet been updated because they

are assigned only after every transfer has been mapped. The subsequent

spiunmapmsg() may therefore unmap the TX mapping again or release

earlier mappings using a NULL or stale device. Using a NULL device can

trigger an oops. An empty SG table does not prevent the NULL dereference

because dmaunmapsg_attrs() accesses the device before checking the

entry count.

Publish both mapping devices before mapping starts and unwind all

failures through _spiunmap_msg(). This clears the mapping flags and

releases each mapping once with the device that created it.

Publishing the devices before the loop also refreshes them when no

transfer needs mapping. No mapping flag is set in that case, so current

users do not use the pointers as mapping owners.