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Subject[PATCH AUTOSEL for 4.14 052/110] crypto: af_alg - Fix race around ctx->rcvused by making it atomic_t
Date
From: Jonathan Cameron <Jonathan.Cameron@huawei.com>

[ Upstream commit af955bf15d2c27496b0269b1f05c26f758c68314 ]

This variable was increased and decreased without any protection.
Result was an occasional misscount and negative wrap around resulting
in false resource allocation failures.

Fixes: 7d2c3f54e6f6 ("crypto: af_alg - remove locking in async callback")
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Reviewed-by: Stephan Mueller <smueller@chronox.de>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
---
crypto/af_alg.c | 4 ++--
crypto/algif_aead.c | 2 +-
crypto/algif_skcipher.c | 2 +-
include/crypto/if_alg.h | 5 +++--
4 files changed, 7 insertions(+), 6 deletions(-)

diff --git a/crypto/af_alg.c b/crypto/af_alg.c
index 53b7fa4cf4ab..4e4640bb82b9 100644
--- a/crypto/af_alg.c
+++ b/crypto/af_alg.c
@@ -693,7 +693,7 @@ void af_alg_free_areq_sgls(struct af_alg_async_req *areq)
unsigned int i;

list_for_each_entry_safe(rsgl, tmp, &areq->rsgl_list, list) {
- ctx->rcvused -= rsgl->sg_num_bytes;
+ atomic_sub(rsgl->sg_num_bytes, &ctx->rcvused);
af_alg_free_sg(&rsgl->sgl);
list_del(&rsgl->list);
if (rsgl != &areq->first_rsgl)
@@ -1192,7 +1192,7 @@ int af_alg_get_rsgl(struct sock *sk, struct msghdr *msg, int flags,

areq->last_rsgl = rsgl;
len += err;
- ctx->rcvused += err;
+ atomic_add(err, &ctx->rcvused);
rsgl->sg_num_bytes = err;
iov_iter_advance(&msg->msg_iter, err);
}
diff --git a/crypto/algif_aead.c b/crypto/algif_aead.c
index 782cb8fec323..f138af18b500 100644
--- a/crypto/algif_aead.c
+++ b/crypto/algif_aead.c
@@ -571,7 +571,7 @@ static int aead_accept_parent_nokey(void *private, struct sock *sk)
INIT_LIST_HEAD(&ctx->tsgl_list);
ctx->len = len;
ctx->used = 0;
- ctx->rcvused = 0;
+ atomic_set(&ctx->rcvused, 0);
ctx->more = 0;
ctx->merge = 0;
ctx->enc = 0;
diff --git a/crypto/algif_skcipher.c b/crypto/algif_skcipher.c
index 7a3e663d54d5..90bc4e0f0785 100644
--- a/crypto/algif_skcipher.c
+++ b/crypto/algif_skcipher.c
@@ -391,7 +391,7 @@ static int skcipher_accept_parent_nokey(void *private, struct sock *sk)
INIT_LIST_HEAD(&ctx->tsgl_list);
ctx->len = len;
ctx->used = 0;
- ctx->rcvused = 0;
+ atomic_set(&ctx->rcvused, 0);
ctx->more = 0;
ctx->merge = 0;
ctx->enc = 0;
diff --git a/include/crypto/if_alg.h b/include/crypto/if_alg.h
index aeec003a566b..ac0eae8372ab 100644
--- a/include/crypto/if_alg.h
+++ b/include/crypto/if_alg.h
@@ -18,6 +18,7 @@
#include <linux/if_alg.h>
#include <linux/scatterlist.h>
#include <linux/types.h>
+#include <linux/atomic.h>
#include <net/sock.h>

#include <crypto/aead.h>
@@ -155,7 +156,7 @@ struct af_alg_ctx {
struct af_alg_completion completion;

size_t used;
- size_t rcvused;
+ atomic_t rcvused;

bool more;
bool merge;
@@ -228,7 +229,7 @@ static inline int af_alg_rcvbuf(struct sock *sk)
struct af_alg_ctx *ctx = ask->private;

return max_t(int, max_t(int, sk->sk_rcvbuf & PAGE_MASK, PAGE_SIZE) -
- ctx->rcvused, 0);
+ atomic_read(&ctx->rcvused), 0);
}

/**
--
2.11.0
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