Re: [PATCH] crypto: vmx - Fix sleep-in-atomic bugs
From: Ondrej Mosnáček <hidden>
Date: 2018-08-21 18:45:35
CC: Paulo Flabiano Smorigo <redacted>, linuxppc-dev@lists.ozlabs.org (Sorry, sent this before reading new e-mails in the thread...) ut 21. 8. 2018 o 17:18 Ondrej Mosnacek [off-list ref] 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 incl=
ude/crypto/algapi.h:424
[ 891.864622] in_atomic(): 1, irqs_disabled(): 0, pid: 12347, name: kcap=
i-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+0xe8/0x16=
4 (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+0=
x1c8/0x260 [vmx_crypto]
[ 891.865993] [c000000338757ad0] [c0000000006c0ee0] skcipher_encrypt_blk=
cipher+0x60/0x80
[ 891.866128] [c000000338757b10] [c0000000006ec504] skcipher_recvmsg+0x4=
24/0x530
[ 891.866283] [c000000338757bd0] [c000000000b00654] sock_recvmsg+0x74/0x=
a0
[ 891.866403] [c000000338757c10] [c000000000b00f64] ___sys_recvmsg+0xf4/=
0x2f0
[ 891.866515] [c000000338757d90] [c000000000b02bb8] __sys_recvmsg+0x68/0=
xe0
[ 891.866631] [c000000338757e30] [c00000000000bbe4] system_call+0x5c/0x7=
0
quoted hunk
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> --- 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_desc=
*desc,
quoted hunk
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_desc=
*desc,
quoted hunk
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_skciph=
er_decrypt(req);
quoted hunk
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, wa=
lk.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();
+ }
}
return ret;
}
--
2.17.1