From: Marcelo Henrique Cerri Subject: Re: [PATCH] crypto: vmx - Fix sleep-in-atomic bugs Date: Tue, 21 Aug 2018 13:41:26 -0300 Message-ID: <20180821164126.GF28751@gallifrey> References: <20180821151623.26061-1-omosnace@redhat.com> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="rMWmSaSbD7nr+du9" Cc: omosnace@redhat.com, Herbert Xu , linux-crypto@vger.kernel.org, Stephan Mueller , Benjamin Herrenschmidt , Paul Mackerras , Michael Ellerman , leo.barbosa@canonical.com, stable@vger.kernel.org, Paulo Flabiano Smorigo , linuxppc-dev@lists.ozlabs.org To: Ondrej =?utf-8?B?TW9zbsOhxI1law==?= Return-path: Content-Disposition: inline In-Reply-To: Sender: stable-owner@vger.kernel.org List-Id: linux-crypto.vger.kernel.org --rMWmSaSbD7nr+du9 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Tue, Aug 21, 2018 at 05:24:45PM +0200, Ondrej Mosn=C3=A1=C4=8Dek wrote: > CC: Paulo Flabiano Smorigo , > linuxppc-dev@lists.ozlabs.org >=20 > (Sorry, sent this before reading new e-mails in the thread...) >=20 > ut 21. 8. 2018 o 17:18 Ondrej Mosnacek nap=C3=ADsal= (a): > > > > This patch fixes sleep-in-atomic bugs in AES-CBC and AES-XTS VMX > > implementations. The problem is that the blkcipher_* functions should > > not be called in atomic context. > > > > The bugs can be reproduced via the AF_ALG interface by trying to > > encrypt/decrypt sufficiently large buffers (at least 64 KiB) using the > > VMX implementations of 'cbc(aes)' or 'xts(aes)'. Such operations then > > trigger BUG in crypto_yield(): > > > > [ 891.863680] BUG: sleeping function called from invalid context at in= clude/crypto/algapi.h:424 > > [ 891.864622] in_atomic(): 1, irqs_disabled(): 0, pid: 12347, name: kc= api-enc > > [ 891.864739] 1 lock held by kcapi-enc/12347: > > [ 891.864811] #0: 00000000f5d42c46 (sk_lock-AF_ALG){+.+.}, at: skciph= er_recvmsg+0x50/0x530 > > [ 891.865076] CPU: 5 PID: 12347 Comm: kcapi-enc Not tainted 4.19.0-0.r= c0.git3.1.fc30.ppc64le #1 > > [ 891.865251] Call Trace: > > [ 891.865340] [c0000003387578c0] [c000000000d67ea4] dump_stack+0xe8/0x= 164 (unreliable) > > [ 891.865511] [c000000338757910] [c000000000172a58] ___might_sleep+0x2= f8/0x310 > > [ 891.865679] [c000000338757990] [c0000000006bff74] blkcipher_walk_don= e+0x374/0x4a0 > > [ 891.865825] [c0000003387579e0] [d000000007e73e70] p8_aes_cbc_encrypt= +0x1c8/0x260 [vmx_crypto] > > [ 891.865993] [c000000338757ad0] [c0000000006c0ee0] skcipher_encrypt_b= lkcipher+0x60/0x80 > > [ 891.866128] [c000000338757b10] [c0000000006ec504] skcipher_recvmsg+0= x424/0x530 > > [ 891.866283] [c000000338757bd0] [c000000000b00654] sock_recvmsg+0x74/= 0xa0 > > [ 891.866403] [c000000338757c10] [c000000000b00f64] ___sys_recvmsg+0xf= 4/0x2f0 > > [ 891.866515] [c000000338757d90] [c000000000b02bb8] __sys_recvmsg+0x68= /0xe0 > > [ 891.866631] [c000000338757e30] [c00000000000bbe4] system_call+0x5c/0= x70 > > > > Fixes: 8c755ace357c ("crypto: vmx - Adding CBC routines for VMX module") > > Fixes: c07f5d3da643 ("crypto: vmx - Adding support for XTS") > > Cc: stable@vger.kernel.org > > Signed-off-by: Ondrej Mosnacek > > --- > > This patch should fix the issue, but I didn't test it. (I'll see if I > > can find some time tomorrow to try and recompile the kernel on a PPC > > machine... in the meantime please review :) > > > > drivers/crypto/vmx/aes_cbc.c | 30 ++++++++++++++---------------- > > drivers/crypto/vmx/aes_xts.c | 19 ++++++++++++------- > > 2 files changed, 26 insertions(+), 23 deletions(-) > > > > diff --git a/drivers/crypto/vmx/aes_cbc.c b/drivers/crypto/vmx/aes_cbc.c > > index 5285ece4f33a..b71895871be3 100644 > > --- a/drivers/crypto/vmx/aes_cbc.c > > +++ b/drivers/crypto/vmx/aes_cbc.c > > @@ -107,24 +107,23 @@ static int p8_aes_cbc_encrypt(struct blkcipher_de= sc *desc, > > ret =3D crypto_skcipher_encrypt(req); > > skcipher_request_zero(req); > > } else { > > - preempt_disable(); > > - pagefault_disable(); > > - enable_kernel_vsx(); > > - > > blkcipher_walk_init(&walk, dst, src, nbytes); > > ret =3D blkcipher_walk_virt(desc, &walk); > > while ((nbytes =3D walk.nbytes)) { > > + preempt_disable(); > > + pagefault_disable(); > > + enable_kernel_vsx(); > > aes_p8_cbc_encrypt(walk.src.virt.addr, > > walk.dst.virt.addr, > > nbytes & AES_BLOCK_MASK, > > &ctx->enc_key, walk.iv, 1); > > + disable_kernel_vsx(); > > + pagefault_enable(); > > + preempt_enable(); > > + > > nbytes &=3D AES_BLOCK_SIZE - 1; > > ret =3D blkcipher_walk_done(desc, &walk, nbytes= ); > > } > > - > > - disable_kernel_vsx(); > > - pagefault_enable(); > > - preempt_enable(); > > } > > > > return ret; > > @@ -147,24 +146,23 @@ static int p8_aes_cbc_decrypt(struct blkcipher_de= sc *desc, > > ret =3D crypto_skcipher_decrypt(req); > > skcipher_request_zero(req); > > } else { > > - preempt_disable(); > > - pagefault_disable(); > > - enable_kernel_vsx(); > > - > > blkcipher_walk_init(&walk, dst, src, nbytes); > > ret =3D blkcipher_walk_virt(desc, &walk); > > while ((nbytes =3D walk.nbytes)) { > > + preempt_disable(); > > + pagefault_disable(); > > + enable_kernel_vsx(); > > aes_p8_cbc_encrypt(walk.src.virt.addr, > > walk.dst.virt.addr, > > nbytes & AES_BLOCK_MASK, > > &ctx->dec_key, walk.iv, 0); > > + disable_kernel_vsx(); > > + pagefault_enable(); > > + preempt_enable(); > > + > > nbytes &=3D AES_BLOCK_SIZE - 1; > > ret =3D blkcipher_walk_done(desc, &walk, nbytes= ); > > } > > - > > - disable_kernel_vsx(); > > - pagefault_enable(); > > - preempt_enable(); > > } > > > > return ret; > > diff --git a/drivers/crypto/vmx/aes_xts.c b/drivers/crypto/vmx/aes_xts.c > > index 8bd9aff0f55f..016ef52390c9 100644 > > --- a/drivers/crypto/vmx/aes_xts.c > > +++ b/drivers/crypto/vmx/aes_xts.c > > @@ -116,13 +116,14 @@ static int p8_aes_xts_crypt(struct blkcipher_desc= *desc, > > ret =3D enc? crypto_skcipher_encrypt(req) : crypto_skci= pher_decrypt(req); > > skcipher_request_zero(req); > > } else { > > + blkcipher_walk_init(&walk, dst, src, nbytes); > > + > > + ret =3D blkcipher_walk_virt(desc, &walk); > > + > > preempt_disable(); > > pagefault_disable(); > > enable_kernel_vsx(); > > > > - blkcipher_walk_init(&walk, dst, src, nbytes); > > - > > - ret =3D blkcipher_walk_virt(desc, &walk); > > iv =3D walk.iv; > > memset(tweak, 0, AES_BLOCK_SIZE); > > aes_p8_encrypt(iv, tweak, &ctx->tweak_key); > > @@ -135,13 +136,17 @@ static int p8_aes_xts_crypt(struct blkcipher_desc= *desc, > > aes_p8_xts_decrypt(walk.src.virt.addr, = walk.dst.virt.addr, > > nbytes & AES_BLOCK_MASK= , &ctx->dec_key, NULL, tweak); > > > > + disable_kernel_vsx(); > > + pagefault_enable(); > > + preempt_enable(); > > + > > nbytes &=3D AES_BLOCK_SIZE - 1; > > ret =3D blkcipher_walk_done(desc, &walk, nbytes= ); > > - } > > > > - disable_kernel_vsx(); > > - pagefault_enable(); > > - preempt_enable(); > > + preempt_disable(); > > + pagefault_disable(); > > + enable_kernel_vsx(); > > + } That doesn't seem right. It would leave preemption disabled when leaving the function. > > } > > return ret; > > } > > -- > > 2.17.1 > > --rMWmSaSbD7nr+du9--