i2c_slave.c: fix buffer overrun on s_i2c_handle_complete() (IDFGH-13973)

[danielcolchete]

Fixing a buffer overrun of i2c_slave->data_buf.

The i2c_ll_read_rxfifo function was using t->rcv_fifo_cnf (the I2C slave reading code's buffer size) as the limit for how many bytes on write on i2c_slave->data_buf.

This buffer size for i2c_slave->data_buf is generally smaller than the buffer that the I2C slave reading code has.

Description

Issue #14803 explains the problem, but TL/DR the i2c_slave_receive() workflow causes memory corruption due to a buffer overrun. And then it generally gets to a Core 0 panic'ed (StoreProhibited). Exception was unhandled. error on runtime.

Related

Fixes #14803

Documentation used for my own test case: https://docs.espressif.com/projects/esp-idf/en/v5.3.1/esp32/api-reference/peripherals/i2c.html

Testing

Tested locally on a couple of ESP32-DevKitC-V4 boards.

Checklist

Before submitting a Pull Request, please ensure the following:

• 🚨 This PR does not introduce breaking changes.
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• Documentation is updated as needed.
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[github-actions]

Warnings

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[mythbuster5]

Thanks for the contribution. We notice that the api in i2c_slave.c has several issues, and lack ease of use. So we are coming with new i2c slave driver in i2c_slave_v2.c (will be online both master and v5.4). Meanwhile, we will slow down the maintainance of i2c_slave.c and focus maintain i2c_slave_v2.c. And i2c_slave.c will be removed in next esp-idf update. I will close this contribution for this reason. Thank you again!

[KaeLL]

@mythbuster5 how does "slow down the maintenance of i2c_slave.c" translates into not accepting memory corruption bugfixes?