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Eric Biggers authored
commit 8f9c4693 upstream. Keys for "authenc" AEADs are formatted as an rtattr containing a 4-byte 'enckeylen', followed by an authentication key and an encryption key. crypto_authenc_extractkeys() parses the key to find the inner keys. However, it fails to consider the case where the rtattr's payload is longer than 4 bytes but not 4-byte aligned, and where the key ends before the next 4-byte aligned boundary. In this case, 'keylen -= RTA_ALIGN(rta->rta_len);' underflows to a value near UINT_MAX. This causes a buffer overread and crash during crypto_ahash_setkey(). Fix it by restricting the rtattr payload to the expected size. Reproducer using AF_ALG: #include <linux/if_alg.h> #include <linux/rtnetlink.h> #include <sys/socket.h> int main() { int fd; struct sockaddr_alg addr = { .salg_type = "aead", .salg_name = "authenc(hmac(sha256),cbc(aes))", }; struct { struct rtattr attr; __be32 en...
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