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Merge #22: Clamp JSON object depth to PHP limit
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54c4015 Clamp JSON object depth to PHP limit (Jeff Garzik)

Pull request description:

  Cherry-picks jgarzik#64 to fix CVE-2019-18936.

  Based on fe2227d

ACKs for top commit:
  MarcoFalke:
    ACK 54c4015 📣

Tree-SHA512: d21458bcfdd37abd84daad46cead0635098d3b1ecd86720c48e724f5e3fcbea39692e1b1fbb2e0d9401a5121df44f280dc6eba8e3ace474c8f4cdb81004a6189
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MarcoFalke committed Dec 16, 2019
2 parents 5a58a46 + 54c4015 commit 98261b1
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2 changes: 2 additions & 0 deletions Makefile.am
Original file line number Diff line number Diff line change
Expand Up @@ -95,6 +95,7 @@ TEST_FILES = \
$(TEST_DATA_DIR)/fail41.json \
$(TEST_DATA_DIR)/fail42.json \
$(TEST_DATA_DIR)/fail44.json \
$(TEST_DATA_DIR)/fail45.json \
$(TEST_DATA_DIR)/fail3.json \
$(TEST_DATA_DIR)/fail4.json \
$(TEST_DATA_DIR)/fail5.json \
Expand All @@ -105,6 +106,7 @@ TEST_FILES = \
$(TEST_DATA_DIR)/pass1.json \
$(TEST_DATA_DIR)/pass2.json \
$(TEST_DATA_DIR)/pass3.json \
$(TEST_DATA_DIR)/pass4.json \
$(TEST_DATA_DIR)/round1.json \
$(TEST_DATA_DIR)/round2.json \
$(TEST_DATA_DIR)/round3.json \
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11 changes: 11 additions & 0 deletions lib/univalue_read.cpp
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Expand Up @@ -8,6 +8,14 @@
#include "univalue.h"
#include "univalue_utffilter.h"

/*
* According to stackexchange, the original json test suite wanted
* to limit depth to 22. Widely-deployed PHP bails at depth 512,
* so we will follow PHP's lead, which should be more than sufficient
* (further stackexchange comments indicate depth > 32 rarely occurs).
*/
static const size_t MAX_JSON_DEPTH = 512;

static bool json_isdigit(int ch)
{
return ((ch >= '0') && (ch <= '9'));
Expand Down Expand Up @@ -323,6 +331,9 @@ bool UniValue::read(const char *raw, size_t size)
stack.push_back(newTop);
}

if (stack.size() > MAX_JSON_DEPTH)
return false;

if (utyp == VOBJ)
setExpect(OBJ_NAME);
else
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1 change: 1 addition & 0 deletions test/fail45.json
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@@ -0,0 +1 @@
[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]
1 change: 1 addition & 0 deletions test/pass4.json
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@@ -0,0 +1 @@
[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]
2 changes: 2 additions & 0 deletions test/unitester.cpp
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Expand Up @@ -114,6 +114,7 @@ static const char *filenames[] = {
"fail41.json", // invalid unicode: unfinished UTF-8
"fail42.json", // valid json with garbage following a nul byte
"fail44.json", // unterminated string
"fail45.json", // nested beyond max depth
"fail3.json",
"fail4.json", // extra comma
"fail5.json",
Expand All @@ -124,6 +125,7 @@ static const char *filenames[] = {
"pass1.json",
"pass2.json",
"pass3.json",
"pass4.json",
"round1.json", // round-trip test
"round2.json", // unicode
"round3.json", // bare string
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