Description

In the Linux kernel, the following vulnerability has been resolved: crypto: af_alg - Fix missing initialisation affecting gcm-aes-s390 Fix af_alg_alloc_areq() to initialise areq->first_rsgl.sgl.sgt.sgl to point to the scatterlist array in areq->first_rsgl.sgl.sgl. Without this, the gcm-aes-s390 driver will oops when it tries to do gcm_walk_start() on req->dst because req->dst is set to the value of areq->first_rsgl.sgl.sgl by _aead_recvmsg() calling aead_request_set_crypt(). The problem comes if an empty ciphertext is passed: the loop in af_alg_get_rsgl() just passes straight out and doesn't set areq->first_rsgl up. This isn't a problem on x86_64 using gcmaes_crypt_by_sg() because, as far as I can tell, that ignores req->dst and only uses req->src[*]. [*] Is this a bug in aesni-intel_glue.c? The s390x oops looks something like: Unable to handle kernel pointer dereference in virtual kernel address space Failing address: 0000000a00000000 TEID: 0000000a00000803 Fault in home space mode while using kernel ASCE. AS:00000000a43a0007 R3:0000000000000024 Oops: 003b ilc:2 [#1] SMP ... Call Trace: [] gcm_walk_start+0x16/0x28 [aes_s390] [] crypto_aead_decrypt+0x9a/0xb8 [] aead_recvmsg+0x478/0x698 [] sock_recvmsg+0x70/0xb0 [] sock_read_iter+0x76/0xa0 [] vfs_read+0x26e/0x2a8 [] ksys_read+0xbc/0x100 [] __do_syscall+0x1d0/0x1f8 [] system_call+0x70/0x98 Last Breaking-Event-Address: [] gcm_aes_crypt+0x104/0xa68 [aes_s390]