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From 9ed3c716b63c77e9b52f71f2dae5464ade6143df Mon Sep 17 00:00:00 2001
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From: Kamil Dudka <kdudka@redhat.com>
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Date: Tue, 19 Mar 2019 13:47:41 +0100
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Subject: [PATCH] Resolves: CVE-2019-3863 - fix integer overflow in user
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 authenticate keyboard interactive
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... that allows out-of-bounds writes
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Upstream-Patch: https://libssh2.org/1.8.0-CVE/CVE-2019-3863.patch
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---
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 src/userauth.c | 13 +++++++++++--
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 1 file changed, 11 insertions(+), 2 deletions(-)
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diff --git a/src/userauth.c b/src/userauth.c
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index 3946cf9..ee924c5 100644
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--- a/src/userauth.c
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+++ b/src/userauth.c
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@@ -1808,8 +1808,17 @@ userauth_keyboard_interactive(LIBSSH2_SESSION * session,
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             for(i = 0; i < session->userauth_kybd_num_prompts; i++) {
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                 /* string    response[1] (ISO-10646 UTF-8) */
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-                session->userauth_kybd_packet_len +=
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-                    4 + session->userauth_kybd_responses[i].length;
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+                 if(session->userauth_kybd_responses[i].length <=
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+                   (SIZE_MAX - 4 - session->userauth_kybd_packet_len) ) {
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+                    session->userauth_kybd_packet_len +=
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+                        4 + session->userauth_kybd_responses[i].length;
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+                }
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+                else {
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+                    _libssh2_error(session, LIBSSH2_ERROR_ALLOC,
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+                                   "Unable to allocate memory for keyboard-"
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+                                   "interactive response packet");
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+                    goto cleanup;
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+                }
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             }
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             /* A new userauth_kybd_data area is to be allocated, free the
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-- 
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2.17.2
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