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

Overview

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

• Linux >= a06347c04c13e380afce0c9816df51f00b83faf1 < d9498ab9a78cb63d78dbe4f221d8cc6c91f285ee
• Linux >= a06347c04c13e380afce0c9816df51f00b83faf1 < 1fc32327b927a6e2cde086f82575c29880844228
• Linux >= a06347c04c13e380afce0c9816df51f00b83faf1 < 8d2c243b79854628ff076c38748c020042f02f57
• Linux >= a06347c04c13e380afce0c9816df51f00b83faf1 < fc3c2bd5b1ec6c7cbc8a50e32d9bcec114f25463
• Linux >= a06347c04c13e380afce0c9816df51f00b83faf1 < 0d723090645b82c1cb27cfd7ebf81f0e7c96bcae
• Linux >= a06347c04c13e380afce0c9816df51f00b83faf1 < db7e464b350969c6ea8340de00d9796e5fd5123b
• Linux >= a06347c04c13e380afce0c9816df51f00b83faf1 < e5eec121f2c3bc4c7022613bedd9121a8aa4c949
• Linux >= a06347c04c13e380afce0c9816df51f00b83faf1 < 1aa3fc769b0c45bd19f8dab1697084c2b3f6d706
• Linux >= a06347c04c13e380afce0c9816df51f00b83faf1 < 7ad21dcfeb5181af0c3ee2608808c0c0a5283aa1
• Linux 4.4

Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.