CVE-2024-50001

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

net/mlx5: Fix error path in multi-packet WQE transmit

Remove the erroneous unmap in case no DMA mapping was established

The multi-packet WQE transmit code attempts to obtain a DMA mapping for

the skb. This could fail, e.g. under memory pressure, when the IOMMU

driver just can't allocate more memory for page tables. While the code

tries to handle this in the path below the err_unmap label it erroneously

unmaps one entry from the sq's FIFO list of active mappings. Since the

current map attempt failed this unmap is removing some random DMA mapping

that might still be required. If the PCI function now presents that IOVA,

the IOMMU may assumes a rogue DMA access and e.g. on s390 puts the PCI

function in error state.

The erroneous behavior was seen in a stress-test environment that created

memory pressure.