Re: [PATCH] net: tls: fix possible race condition between do_tls_getsockopt_conf() and do_tls_setsockopt_conf()
From: Florian Westphal <fw@strlen.de>
Date: 2023-02-24 12:06:49
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lkml
Hangyu Hua [off-list ref] wrote:
ctx->crypto_send.info is not protected by lock_sock in do_tls_getsockopt_conf(). A race condition between do_tls_getsockopt_conf() and do_tls_setsockopt_conf() can cause a NULL point dereference or use-after-free read when memcpy.
Its good practice to quote the relevant parts of the splat here.
quoted hunk ↗ jump to hunk
Fixes: 3c4d7559159b ("tls: kernel TLS support") Signed-off-by: Hangyu Hua <redacted> --- net/tls/tls_main.c | 2 ++ 1 file changed, 2 insertions(+)diff --git a/net/tls/tls_main.c b/net/tls/tls_main.c index 3735cb00905d..4956f5149b8e 100644 --- a/net/tls/tls_main.c +++ b/net/tls/tls_main.c@@ -374,6 +374,7 @@ static int do_tls_getsockopt_conf(struct sock *sk, char __user *optval, } /* get user crypto info */ + lock_sock(sk); if (tx) { crypto_info = &ctx->crypto_send.info; cctx = &ctx->tx;@@ -381,6 +382,7 @@ static int do_tls_getsockopt_conf(struct sock *sk, char __user *optval, crypto_info = &ctx->crypto_recv.info; cctx = &ctx->rx; } + release_sock(sk);
Could you elaborate how this fixes a UAF bug? AFAIU do_tls_setsockopt_conf uses ctx-> as scratch space, but this means that getsockopt can see partial states. If so, can the setsockopt part be changed so that reads only see consistent states?