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Luxiao Xu
dcab71a701
Commit6709d4b7bc("net: nfc: Fix use-after-free caused by nfc_llcp_find_local") attempted to fix a use-after-free (UAF) issue by invoking nfc_llcp_local_put(local) after accessing local->gb. However, if the reference count drops to zero, local is freed immediately, leading to a use-after-free when callers access the returned pointer. Alternative approaches using dynamic allocation (e.g. kmemdup) introduced memory leaks because callers consistently treat the returned pointer as borrowed memory. Fix this properly by refactoring nfc_llcp_general_bytes() and nfc_get_local_general_bytes() to accept a caller-provided output buffer (out_gb) and its maximum length (gb_max_len). The general bytes are safely copied into out_gb before calling nfc_llcp_local_put(local), ensuring safe lifetime management without ownership transfer complications. Update all callers across drivers (microread, pn533, pn544, st21nfca, digital_dep, and nci) to provide their own destination buffers and pass them to nfc_get_local_general_bytes(). Fixes:6709d4b7bc("net: nfc: Fix use-after-free caused by nfc_llcp_find_local") Cc: [email protected] Reported-by: Vega <[email protected]> Assisted-by: LLM Signed-off-by: Luxiao Xu <[email protected]> Signed-off-by: Ren Wei <[email protected]> Reviewed-by: Simon Horman <[email protected]> Link: https://patch.msgid.link/3cbaac3bee23f8ff3a3284ed32d347696eb1d208.1788841683.git.rakukuip@gmail.com Signed-off-by: David Heidelberg <[email protected]>