On Thu, Jul 27, 2023 at 7:55 AM Sven Schnelle <svens@xxxxxxxxxxxxx> wrote: > > David Howells <dhowells@xxxxxxxxxx> writes: > > > > > 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: > > [<000003ff7fc3d47e>] gcm_walk_start+0x16/0x28 [aes_s390] > > [<00000000a2a342f2>] crypto_aead_decrypt+0x9a/0xb8 > > [<00000000a2a60888>] aead_recvmsg+0x478/0x698 > > [<00000000a2e519a0>] sock_recvmsg+0x70/0xb0 > > [<00000000a2e51a56>] sock_read_iter+0x76/0xa0 > > [<00000000a273e066>] vfs_read+0x26e/0x2a8 > > [<00000000a273e8c4>] ksys_read+0xbc/0x100 > > [<00000000a311d808>] __do_syscall+0x1d0/0x1f8 > > [<00000000a312ff30>] system_call+0x70/0x98 > > Last Breaking-Event-Address: > > [<000003ff7fc3e6b4>] gcm_aes_crypt+0x104/0xa68 [aes_s390] > > > > Fixes: c1abe6f570af ("crypto: af_alg: Use extract_iter_to_sg() to create scatterlists") > > Reported-by: Ondrej Mosnáček <omosnacek@xxxxxxxxx> > > Link: https://lore.kernel.org/r/CAAUqJDuRkHE8fPgZJGaKjUjd3QfGwzfumuJBmStPqBhubxyk_A@xxxxxxxxxxxxxx/ > > Signed-off-by: David Howells <dhowells@xxxxxxxxxx> > > cc: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx> > > cc: Sven Schnelle <svens@xxxxxxxxxxxxx> > > cc: Harald Freudenberger <freude@xxxxxxxxxxxxxxxxxx> > > cc: "David S. Miller" <davem@xxxxxxxxxxxxx> > > cc: Paolo Abeni <pabeni@xxxxxxxxxx> > > cc: linux-crypto@xxxxxxxxxxxxxxx > > cc: linux-s390@xxxxxxxxxxxxxxx > > cc: regressions@xxxxxxxxxxxxxxx > > --- > > crypto/af_alg.c | 1 + > > 1 file changed, 1 insertion(+) > > > > diff --git a/crypto/af_alg.c b/crypto/af_alg.c > > index 06b15b9f661c..9ee8575d3b1a 100644 > > --- a/crypto/af_alg.c > > +++ b/crypto/af_alg.c > > @@ -1192,6 +1192,7 @@ struct af_alg_async_req *af_alg_alloc_areq(struct sock *sk, > > > > areq->areqlen = areqlen; > > areq->sk = sk; > > + areq->first_rsgl.sgl.sgt.sgl = areq->first_rsgl.sgl.sgl; > > areq->last_rsgl = NULL; > > INIT_LIST_HEAD(&areq->rsgl_list); > > areq->tsgl = NULL; > > Just tested, with this fix the kernel no longer crashes. Thanks! > > Tested-by: Sven Schnelle <svens@xxxxxxxxxxxxx> Same here. Thanks for the fix! Tested-by: Ondrej Mosnáček <omosnacek@xxxxxxxxx>