CVE-2026-80802nfc: fdp: bound the device-reported read length and fix an skb leak

Official description

In the Linux kernel, the following vulnerability has been resolved: nfc: fdp: bound the device-reported read length and fix an skb leak fdp_nci_i2c_read() takes the next packet length from two device-supplied bytes and never validates it. The value is a u16 used as the i2c_master_recv() count into a 261-byte on-stack buffer: a malicious, counterfeit or malfunctioning controller (or an i2c bus interposer) can drive it far past the buffer for a stack out-of-bounds write that clobbers the canary and return address, or below the minimum frame size (directly, or by truncating the computed sum) so the header/LRC strip and the next length read run past a short receive. Reject a length outside [FDP_NCI_I2C_MIN_PAYLOAD, FDP_NCI_I2C_MAX_PAYLOAD], as a corrupted packet already is, and force resynchronization. The same loop allocates one data skb per iteration and assumes a length packet followed by a data packet; a device that sends two data packets in one call leaks the first skb when the second allocation overwrites it. Free a previously allocated skb before allocating the next.

Affected packages & fixed versions

Affected products (as reported)

References

• https://git.kernel.org/stable/c/d9498ab9a78cb63d78dbe4f221d8cc6c91f285ee
• https://git.kernel.org/stable/c/1fc32327b927a6e2cde086f82575c29880844228
• https://git.kernel.org/stable/c/8d2c243b79854628ff076c38748c020042f02f57
• https://git.kernel.org/stable/c/fc3c2bd5b1ec6c7cbc8a50e32d9bcec114f25463
• https://git.kernel.org/stable/c/0d723090645b82c1cb27cfd7ebf81f0e7c96bcae
• https://git.kernel.org/stable/c/db7e464b350969c6ea8340de00d9796e5fd5123b
• https://git.kernel.org/stable/c/e5eec121f2c3bc4c7022613bedd9121a8aa4c949
• https://git.kernel.org/stable/c/1aa3fc769b0c45bd19f8dab1697084c2b3f6d706
• https://git.kernel.org/stable/c/7ad21dcfeb5181af0c3ee2608808c0c0a5283aa1