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commit a699c44ea18d83fe99314155ed35a87092ce68c9 |
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Author: Michael Buckley <michael@panic.com> |
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Date: Wed Dec 5 12:01:34 2018 -0800 |
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|
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Additional length checks to prevent out-of-bounds reads and writes in _libssh2_packet_add(). |
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|
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diff --git a/src/packet.c b/src/packet.c |
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index 5f1feb8..1d50444 100644 |
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--- a/src/packet.c |
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+++ b/src/packet.c |
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@@ -775,8 +775,8 @@ _libssh2_packet_add(LIBSSH2_SESSION * session, unsigned char *data, |
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uint32_t len = _libssh2_ntohu32(data + 5); |
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unsigned char want_reply = 1; |
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|
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- if(len < (datalen - 10)) |
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- want_reply = data[9 + len]; |
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+ if((len + 9) < datalen) |
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+ want_reply = data[len + 9]; |
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|
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_libssh2_debug(session, |
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LIBSSH2_TRACE_CONN, |
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@@ -784,6 +784,7 @@ _libssh2_packet_add(LIBSSH2_SESSION * session, unsigned char *data, |
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channel, len, data + 9, want_reply); |
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|
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if (len == sizeof("exit-status") - 1 |
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+ && (sizeof("exit-status") - 1 + 9) <= datalen |
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&& !memcmp("exit-status", data + 9, |
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sizeof("exit-status") - 1)) { |
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|
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@@ -792,7 +793,7 @@ _libssh2_packet_add(LIBSSH2_SESSION * session, unsigned char *data, |
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channelp = |
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_libssh2_channel_locate(session, channel); |
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|
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- if (channelp) { |
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+ if (channelp && (sizeof("exit-status") + 13) <= datalen) { |
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channelp->exit_status = |
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_libssh2_ntohu32(data + 9 + sizeof("exit-status")); |
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_libssh2_debug(session, LIBSSH2_TRACE_CONN, |
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@@ -805,13 +806,14 @@ _libssh2_packet_add(LIBSSH2_SESSION * session, unsigned char *data, |
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|
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} |
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else if (len == sizeof("exit-signal") - 1 |
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+ && (sizeof("exit-signal") - 1 + 9) <= datalen |
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&& !memcmp("exit-signal", data + 9, |
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sizeof("exit-signal") - 1)) { |
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/* command terminated due to signal */ |
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if(datalen >= 20) |
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channelp = _libssh2_channel_locate(session, channel); |
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|
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- if (channelp) { |
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+ if (channelp && (sizeof("exit-signal") + 13) <= datalen) { |
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/* set signal name (without SIG prefix) */ |
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uint32_t namelen = |
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_libssh2_ntohu32(data + 9 + sizeof("exit-signal")); |
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@@ -820,9 +822,9 @@ _libssh2_packet_add(LIBSSH2_SESSION * session, unsigned char *data, |
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if (!channelp->exit_signal) |
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rc = _libssh2_error(session, LIBSSH2_ERROR_ALLOC, |
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"memory for signal name"); |
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- else { |
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+ else if ((sizeof("exit-signal") + 13 + namelen <= datalen)) { |
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memcpy(channelp->exit_signal, |
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- data + 13 + sizeof("exit_signal"), namelen); |
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+ data + 13 + sizeof("exit-signal"), namelen); |
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channelp->exit_signal[namelen] = '\0'; |
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/* TODO: save error message and language tag */ |
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_libssh2_debug(session, LIBSSH2_TRACE_CONN, |
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