Add bounds check on AES-CTS input length to prevent integer overflow#422
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padelsbach merged 1 commit intoJul 1, 2026
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The CTS encrypt/decrypt helpers cast the block count to int, so an inLen above 0x7FFFFFFF overflows blocks*AES_BLOCK_SIZE and smashes the stack copy. Not reachable via EVP_CipherUpdate (its inl is int); guard added as defense in depth for a caller driving OSSL_FUNC_cipher_update directly.
padelsbach
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Jul 1, 2026
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The AES-CTS encrypt/decrypt helpers in
wp_aes_stream.ccompute the block count as a signedint, so aninLenabove0x7FFFFFFFoverflowsblocks * AES_BLOCK_SIZE. The corrupted (negative) value then explodesinLenviainLen -= blocks * AES_BLOCK_SIZE, leading to an out-of-boundsXMEMCPYinto the 32-bytectsBlockstack buffer.Adds an upper-bound guard in
wp_aes_stream_doit(next to the existing lower-bound check) covering both the encrypt and decrypt paths.Not reachable through
EVP_CipherUpdate(itsinlisint, so input is already capped atINT_MAX); the guard is defense in depth for a caller drivingOSSL_FUNC_cipher_updatedirectly. No new test — triggering would require a >2 GB input that the EVP API can't pass; existing CTS KAT/KRB/error-case tests pass unchanged.Fixes Fenrir F-4380 and F-4381