spi: axi-spi-engine: fix use after free after timeout #2292
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This fixes a use after free that can happen if the watchdog timer times out on an SPI message then another message is attempted. The following struct spi_engine members point to memory managed by the spi framework struct spi_message *msg; struct spi_transfer *tx_xfer; const uint8_t *tx_buf; struct spi_transfer *rx_xfer; uint8_t *rx_buf; During normal operation, tx_xfer and rx_xfer set to NULL by spi_engine_xfer_next() when the last xfer of a message is completed. However, this code path is not taken when the watchdog timer times out and therefore tx_xfer and rx_xfer are not set to NULL and still point to memory that gets freed by spi_finalize_current_message(). When the next message is attempted, spi_engine_transfer_one() will call spi_engine_xfer_next() with the old pointers and will attempt to dereference them. This can cause a crash. To fix this, always set tx_xfer and rx_xfer to NULL before calling spi_finalize_current_message(). Fixes: fde5597 ("spi: axi-spi-engine: Add watchdog timer") Signed-off-by: David Lechner <dlechner@baylibre.com>
nunojsa
approved these changes
Oct 18, 2023
mhennerich
approved these changes
Oct 18, 2023
amiclaus
approved these changes
Oct 18, 2023
I checked and the watchdog timer patch has not been upstreamed. |
Alright... I guess it will be then part of the work in syncing up this driver (plus offload support). I'll then merge this and it can be squashed with the watchdog patch when upstreaming. |
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This fixes a use after free that can happen if the watchdog timer times out on an SPI message then another message is attempted.
The following struct spi_engine members point to memory managed by the spi framework
During normal operation, tx_xfer and rx_xfer set to NULL by spi_engine_xfer_next() when the last xfer of a message is completed. However, this code path is not taken when the watchdog timer times out and therefore tx_xfer and rx_xfer are not set to NULL and still point to memory that gets freed by spi_finalize_current_message().
When the next message is attempted, spi_engine_transfer_one() will call spi_engine_xfer_next() with the old pointers and will attempt to dereference them. This can cause a crash.
To fix this, always set tx_xfer and rx_xfer to NULL before calling spi_finalize_current_message().
Fixes: fde5597 ("spi: axi-spi-engine: Add watchdog timer")
Fixes: #2287