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From cc573aafb6f4b24bce9b82f308e92b9723a73024 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 13:22:24 +0100
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Subject: [PATCH] Resolves: CVE-2019-3856 - fix integer overflow in keyboard
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interactive handling
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... resulting in out of bounds write
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Upstream-Patch: https://libssh2.org/1.8.0-CVE/CVE-2019-3856.patch
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I believe that:
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`(session->userauth_kybd_num_prompts && session->userauth_kybd_num_prompts > 100)`
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... can be simplified as:
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`(session->userauth_kybd_num_prompts > 100)`
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Signed-off-by: Kamil Dudka <kdudka@redhat.com>
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---
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src/userauth.c | 7 +++++++
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1 file changed, 7 insertions(+)
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diff --git a/src/userauth.c b/src/userauth.c
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index cdfa25e..3946cf9 100644
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--- a/src/userauth.c
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+++ b/src/userauth.c
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@@ -1734,6 +1734,13 @@ userauth_keyboard_interactive(LIBSSH2_SESSION * session,
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/* int num-prompts */
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session->userauth_kybd_num_prompts = _libssh2_ntohu32(s);
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s += 4;
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+ if(session->userauth_kybd_num_prompts &&
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+ session->userauth_kybd_num_prompts > 100) {
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+ _libssh2_error(session, LIBSSH2_ERROR_OUT_OF_BOUNDARY,
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+ "Too many replies for "
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+ "keyboard-interactive prompts");
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+ goto cleanup;
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+ }
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if(session->userauth_kybd_num_prompts) {
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session->userauth_kybd_prompts =
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--
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2.17.2
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