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Greg Kroah-Hartman
46ce8be2ce
The NFC-A anti-collision cascade in digital_in_recv_sdd_res() appends 3 or 4 bytes to target->nfcid1 on each round, but the number of cascade rounds is controlled entirely by the peer device. The peer sets the cascade tag in the SDD_RES (deciding 3 vs 4 bytes) and the cascade-incomplete bit in the SEL_RES (deciding whether another round follows). ISO 14443-3 limits NFC-A to three cascade levels and target->nfcid1 is sized accordingly (NFC_NFCID1_MAXSIZE = 10), but nothing in the driver actually enforces this. This means a malicious peer can keep the cascade running, writing past the heap-allocated nfc_target with each round. Fix this by rejecting the response when the accumulated UID would exceed the buffer. Commite329e71013("NFC: nci: Bounds check struct nfc_target arrays") fixed similar missing checks against the same field on the NCI path. Cc: Simon Horman <[email protected]> Cc: Kees Cook <[email protected]> Cc: Thierry Escande <[email protected]> Cc: Samuel Ortiz <[email protected]> Fixes:2c66daecc4("NFC Digital: Add NFC-A technology support") Cc: stable <[email protected]> Assisted-by: gregkh_clanker_t1000 Signed-off-by: Greg Kroah-Hartman <[email protected]> Link: https://patch.msgid.link/2026040913-figure-seducing-bd3f@gregkh Signed-off-by: Jakub Kicinski <[email protected]>