mmc: sdhci: fix low memory corruption
When dma mapping (dma_map_sg) fails in sdhci_pre_dma_transfer, -EINVAL is returned. There are 3 callers of sdhci_pre_dma_transfer: * sdhci_pre_req and sdhci_adma_table_pre: handle negative return * sdhci_prepare_data: handles 0 (error) and "else" (good) only sdhci_prepare_data is therefore broken. When it receives -EINVAL from sdhci_pre_dma_transfer, it assumes 1 sg mapping was mapped. Later, this non-existent mapping with address 0 is kmap'ped and written to: Corrupted low memory at ffff880000001000 (1000 phys) = 22b7d67df2f6d1cf Corrupted low memory at ffff880000001008 (1008 phys) = 63848a5216b7dd95 Corrupted low memory at ffff880000001010 (1010 phys) = 330eb7ddef39e427 Corrupted low memory at ffff880000001018 (1018 phys) = 8017ac7295039bda Corrupted low memory at ffff880000001020 (1020 phys) = 8ce039eac119074f ... So teach sdhci_prepare_data to understand negative return values from sdhci_pre_dma_transfer and disable DMA in that case, as well as for zero. It was introduced in 348487cb (mmc: sdhci: use pipeline mmc requests to improve performance). The commit seems to be suspicious also by assigning host->sg_count both in sdhci_pre_dma_transfer and sdhci_adma_table_pre. Signed-off-by: NJiri Slaby <jslaby@suse.cz> Cc: stable@vger.kernel.org # 4.0+ Fixes: 348487cb Cc: Ulf Hansson <ulf.hansson@linaro.org> Cc: Haibo Chen <haibo.chen@freescale.com> Signed-off-by: NUlf Hansson <ulf.hansson@linaro.org>
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