[PATCH 6.1 025/197] net: tls: fix use-after-free with partial reads and async decrypt

Greg Kroah-Hartman
2024-02-20T20:59:12Z

From: Sabrina Dubroca <sd@queasysnail.net>

[ Upstream commit 32b55c5ff9103b8508c1e04bfa5a08c64e7a925f ]

tls_decrypt_sg doesn't take a reference on the pages from clear_skb,
so the put_page() in tls_decrypt_done releases them, and we trigger
a use-after-free in process_rx_list when we try to read from the
partially-read skb.

Fixes: fd31f3996af2 ("tls: rx: decrypt into a fresh skb")
Signed-off-by: Sabrina Dubroca <sd@queasysnail.net>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Reviewed-by: Simon Horman <horms@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
net/tls/tls_sw.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/net/tls/tls_sw.c b/net/tls/tls_sw.c
index ee11932237c0..d651c50746a8 100644
--- a/net/tls/tls_sw.c
+++ b/net/tls/tls_sw.c
@@ -62,6 +62,7 @@ struct tls_decrypt_ctx {
u8 iv[MAX_IV_SIZE];
u8 aad[TLS_MAX_AAD_SIZE];
u8 tail;
+ bool free_sgout;
struct scatterlist sg[];
};

@@ -186,7 +187,6 @@ static void tls_decrypt_done(crypto_completion_data_t *data, int err)
struct aead_request *aead_req = crypto_get_completion_data(data);
struct crypto_aead *aead = crypto_aead_reqtfm(aead_req);
struct scatterlist *sgout = aead_req->dst;
- struct scatterlist *sgin = aead_req->src;
struct tls_sw_context_rx *ctx;
struct tls_decrypt_ctx *dctx;
struct tls_context *tls_ctx;
@@ -212,7 +212,7 @@ static void tls_decrypt_done(crypto_completion_data_t *data, int err)
}

/* Free the destination pages if skb was not decrypted inplace */
- if (sgout != sgin) {
+ if (dctx->free_sgout) {
/* Skip the first S/G entry as it points to AAD */
for_each_sg(sg_next(sgout), sg, UINT_MAX, pages) {
if (!sg)
@@ -1653,6 +1653,7 @@ static int tls_decrypt_sg(struct sock *sk, struct iov_iter *out_iov,
} else if (out_sg) {
memcpy(sgout, out_sg, n_sgout * sizeof(*sgout));
}
+ dctx->free_sgout = !!pages;

/* Prepare and submit AEAD request */
err = tls_do_decryption(sk, sgin, sgout, dctx->iv,
--
2.43.0