Fixed differently upstream as commit 2d97591ef43d ("crypto: af_alg - consolidation of duplicate code")

The SGL is MAX_SGL_ENTS + 1 in size. The last SG entry is used for the
chaining and is properly updated with the sg_chain invocation. During
the filling-in of the initial SG entries, sg_mark_end is called for each
SG entry. This is appropriate as long as no additional SGL is chained
with the current SGL. However, when a new SGL is chained and the last
SG entry is updated with sg_chain, the last but one entry still contains
the end marker from the sg_mark_end. This end marker must be removed as
otherwise a walk of the chained SGLs will cause a NULL pointer
dereference at the last but one SG entry, because sg_next will return
NULL.

The patch only applies to all kernels up to and including 4.13. The
patch 2d97591ef43d0587be22ad1b0d758d6df4999a0b added to 4.14-rc1
introduced a complete new code base which addresses this bug in
a different way. Yet, that patch is too invasive for stable kernels
and was therefore not marked for stable.

Fixes: 8ff590903d5fc ("crypto: algif_skcipher - User-space interface for skcipher operations")
Signed-off-by: Stephan Mueller <smueller@chronox.de>
Acked-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

commit 445a582738de6802669aeed9c33ca406c23c3b1f upstream.

For asynchronous operation, SGs are allocated without a page mapped to
them or with a page that is not used (ref-counted). If the SGL is freed,
the code must only call put_page for an SG if there was a page assigned
and ref-counted in the first place.

This fixes a kernel crash when using io_submit with more than one iocb
using the sendmsg and sendpage (vmsplice/splice) interface.

Signed-off-by: Stephan Mueller <smueller@chronox.de>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

The async path cannot use MAY_BACKLOG because it is not meant to
block, which is what MAY_BACKLOG does.  On the other hand, both
the sync and async paths can make use of MAY_SLEEP.

Cc: stable@vger.kernel.org
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

Any access to non-constant bits of the private context must be
done under the socket lock, in particular, this includes ctx->req.

This patch moves such accesses under the lock, and fetches the
tfm from the parent socket which is guaranteed to be constant,
rather than from ctx->req.

Cc: stable@vger.kernel.org
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

The async path in algif_skcipher assumes that the crypto completion
function will be called with the original request.  This is not
necessarily the case.  In fact there is no need for this anyway
since we already embed information into the request with struct
skcipher_async_req.

This patch adds a pointer to that struct and then passes it as
the data to the callback function.

Cc: stable@vger.kernel.org
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Tested-by: Tadeusz Struk <tadeusz.struk@intel.com>

Pull crypto fixes from Herbert Xu:
 "This fixes the following issues:

  API:
   - A large number of bug fixes for the af_alg interface, credit goes
     to Dmitry Vyukov for discovering and reporting these issues.

  Algorithms:
   - sw842 needs to select crc32.
   - The soft dependency on crc32c is now in the correct spot.

  Drivers:
   - The atmel AES driver needs HAS_DMA.
   - The atmel AES driver was a missing break statement, fortunately
     it's only a debug function.
   - A number of bug fixes for the Intel qat driver"

* 'linus' of git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6: (24 commits)
  crypto: algif_skcipher - sendmsg SG marking is off by one
  crypto: crc32c - Fix crc32c soft dependency
  crypto: algif_skcipher - Load TX SG list after waiting
  crypto: atmel-aes - Add missing break to atmel_aes_reg_name
  crypto: algif_skcipher - Fix race condition in skcipher_check_key
  crypto: algif_hash - Fix race condition in hash_check_key
  crypto: CRYPTO_DEV_ATMEL_AES should depend on HAS_DMA
  lib: sw842: select crc32
  crypto: af_alg - Forbid bind(2) when nokey child sockets are present
  crypto: algif_skcipher - Remove custom release parent function
  crypto: algif_hash - Remove custom release parent function
  crypto: af_alg - Allow af_af_alg_release_parent to be called on nokey path
  crypto: qat - update init_esram for C3xxx dev type
  crypto: qat - fix timeout issues
  crypto: qat - remove to call get_sram_bar_id for qat_c3xxx
  crypto: algif_skcipher - Add key check exception for cipher_null
  crypto: skcipher - Add crypto_skcipher_has_setkey
  crypto: algif_hash - Require setkey before accept(2)
  crypto: hash - Add crypto_ahash_has_setkey
  crypto: algif_skcipher - Add nokey compatibility path
  ...

We mark the end of the SG list in sendmsg and sendpage and unmark
it on the next send call.  Unfortunately the unmarking in sendmsg
is off-by-one, leading to an SG list that is too short.

Fixes: 0f477b655a52 ("crypto: algif - Mark sgl end at the end of data")
Cc: stable@vger.kernel.org
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

We need to load the TX SG list in sendmsg(2) after waiting for
incoming data, not before.

Cc: stable@vger.kernel.org
Reported-by: Dmitry Vyukov <dvyukov@google.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Tested-by: Dmitry Vyukov <dvyukov@google.com>

We need to lock the child socket in skcipher_check_key as otherwise
two simultaneous calls can cause the parent socket to be freed.

Cc: stable@vger.kernel.org
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

This patch removes the custom release parent function as the
generic af_alg_release_parent now works for nokey sockets too.

Cc: stable@vger.kernel.org
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>