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.
• All CI checks (GH Actions) pass.
• Documentation is updated as needed.
• Tests are updated or added as necessary.
• Code is well-commented, especially in complex areas.
• Git history is clean — commits are squashed to the minimum necessary.

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[github-actions]

Warnings

⚠️

Some issues found for the commit messages in this PR: the commit message "i2c_slave.c: fix buffer overrun on s_i2c_handle_complete()": body's lines must not be longer than 100 characters summary looks empty type/action looks empty Please fix these commit messages - here are some basic tips: follow Conventional Commits style correct format of commit message should be: <type/action>(<scope/component>): <summary>, for example fix(esp32): Fixed startup timeout issue allowed types are: change,ci,docs,feat,fix,refactor,remove,revert,test sufficiently descriptive message summary should be between 20 to 72 characters and start with upper case letter avoid Jira references in commit messages (unavailable/irrelevant for our customers) TIP: Install pre-commit hooks and run this check when committing (uses the Conventional Precommit Linter).

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