Re: [PATCH v2] crypto: vmx - Fix sleep-in-atomic bugs

-- Regards, Marcelo On Wed, Aug 22, 2018 at 08:26:31AM +0200, Ondrej Mosnacek wrote: > 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 include/crypto/algapi.h:424 > [ 891.864622] in_atomic(): 1, irqs_disabled(): 0, pid: 12347, name: kcapi-enc > [ 891.864739] 1 lock held by kcapi-enc/12347: > [ 891.864811] #0: 00000000f5d42c46 (sk_lock-AF_ALG){+.+.}, at: skcipher_recvmsg+0x50/0x530 > [ 891.865076] CPU: 5 PID: 12347 Comm: kcapi-enc Not tainted 4.19.0-0.rc0.git3.1.fc30.ppc64le #1 > [ 891.865251] Call Trace: > [ 891.865340] [c0000003387578c0] [c000000000d67ea4] dump_stack+0xe8/0x164 (unreliable) > [ 891.865511] [c000000338757910] [c000000000172a58] ___might_sleep+0x2f8/0x310 > [ 891.865679] [c000000338757990] [c0000000006bff74] blkcipher_walk_done+0x374/0x4a0 > [ 891.865825] [c0000003387579e0] [d000000007e73e70] p8_aes_cbc_encrypt+0x1c8/0x260 [vmx_crypto] > [ 891.865993] [c000000338757ad0] [c0000000006c0ee0] skcipher_encrypt_blkcipher+0x60/0x80 > [ 891.866128] [c000000338757b10] [c0000000006ec504] skcipher_recvmsg+0x424/0x530 > [ 891.866283] [c000000338757bd0] [c000000000b00654] sock_recvmsg+0x74/0xa0 > [ 891.866403] [c000000338757c10] [c000000000b00f64] ___sys_recvmsg+0xf4/0x2f0 > [ 891.866515] [c000000338757d90] [c000000000b02bb8] __sys_recvmsg+0x68/0xe0 > [ 891.866631] [c000000338757e30] [c00000000000bbe4] system_call+0x5c/0x70 > > 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 omosnace@redhat.com > --- > Still untested, please test and review if possible. > > Changes in v2: > - fix leaving preemtption, etc. disabled when leaving the function > (I switched to the more obvious and less efficient variant for the > sake of clarity.) > > drivers/crypto/vmx/aes_cbc.c | 30 ++++++++++++++---------------- > drivers/crypto/vmx/aes_xts.c | 21 ++++++++++++++------- > 2 files changed, 28 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_desc *desc, > ret = crypto_skcipher_encrypt(req); > skcipher_request_zero(req); > } else { > - preempt_disable(); > - pagefault_disable(); > - enable_kernel_vsx(); > - > blkcipher_walk_init(&walk, dst, src, nbytes); > ret = blkcipher_walk_virt(desc, &walk); > while ((nbytes = 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 &= AES_BLOCK_SIZE - 1; > ret = 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_desc *desc, > ret = crypto_skcipher_decrypt(req); > skcipher_request_zero(req); > } else { > - preempt_disable(); > - pagefault_disable(); > - enable_kernel_vsx(); > - > blkcipher_walk_init(&walk, dst, src, nbytes); > ret = blkcipher_walk_virt(desc, &walk); > while ((nbytes = 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 &= AES_BLOCK_SIZE - 1; > ret = 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..e9954a7d4694 100644 > --- a/drivers/crypto/vmx/aes_xts.c > +++ b/drivers/crypto/vmx/aes_xts.c > @@ -116,32 +116,39 @@ static int p8_aes_xts_crypt(struct blkcipher_desc *desc, > ret = enc? crypto_skcipher_encrypt(req) : crypto_skcipher_decrypt(req); > skcipher_request_zero(req); > } else { > + blkcipher_walk_init(&walk, dst, src, nbytes); > + > + ret = blkcipher_walk_virt(desc, &walk); > + > preempt_disable(); > pagefault_disable(); > enable_kernel_vsx(); > > - blkcipher_walk_init(&walk, dst, src, nbytes); > - > - ret = blkcipher_walk_virt(desc, &walk); > iv = walk.iv; > memset(tweak, 0, AES_BLOCK_SIZE); > aes_p8_encrypt(iv, tweak, &ctx->tweak_key); > > + disable_kernel_vsx(); > + pagefault_enable(); > + preempt_enable(); > + > while ((nbytes = walk.nbytes)) { > + preempt_disable(); > + pagefault_disable(); > + enable_kernel_vsx(); > if (enc) > aes_p8_xts_encrypt(walk.src.virt.addr, walk.dst.virt.addr, > nbytes & AES_BLOCK_MASK, &ctx->enc_key, NULL, tweak); > else > 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 &= AES_BLOCK_SIZE - 1; > ret = blkcipher_walk_done(desc, &walk, nbytes); > } > - > - disable_kernel_vsx(); > - pagefault_enable(); > - preempt_enable(); > } > return ret; > } > -- > 2.17.1 >