From 12220c8b72b633e7292c2fb12f1273dae1cada2e Mon Sep 17 00:00:00 2001 From: ph10 Date: Fri, 18 Nov 2016 18:59:37 +0000 Subject: [PATCH] Fix overrun bug caused by conditional with assertion using too much memory. --- ChangeLog | 7 ++++ HACKING | 4 +- src/pcre2_compile.c | 95 ++++++++++++++++++++++++++----------------- testdata/testinput2 | 4 ++ testdata/testoutput18 | 2 +- testdata/testoutput2 | 8 +++- 6 files changed, 79 insertions(+), 41 deletions(-) diff --git a/ChangeLog b/ChangeLog index 57d9ec0..9e754d5 100644 --- a/ChangeLog +++ b/ChangeLog @@ -82,6 +82,13 @@ copied). (i) An insufficient memory size was being computed for compiling with PCRE2_AUTO_CALLOUT. + + (j) A conditional group with an assertion condition used more memory than was + allowed for it during parsing, so too many of them could therefore + overrun a buffer. + + (k) If parsing a pattern exactly filled the buffer, the internal test for + overrun did not check when the final META_END item was added. 4. Back references are now permitted in lookbehind assertions when there are no duplicated group numbers (that is, (?| has not been used), and, if the diff --git a/HACKING b/HACKING index c51da7b..85b52c9 100644 --- a/HACKING +++ b/HACKING @@ -186,6 +186,7 @@ META_CLASS_EMPTY_NOT [^] negative empty class - ditto META_CLASS_END ] end of non-empty class META_CLASS_NOT [^ start non-empty negative class META_COMMIT (*COMMIT) +META_COND_ASSERT (?(?assertion) META_DOLLAR $ metacharacter META_DOT . metacharacter META_END End of pattern (this value is 0x80000000) @@ -274,9 +275,8 @@ This one is followed by an offset, for use in error messages, then a number: META_COND_NUMBER (?([+-]digits) -The following are followed just by an offset, for use in error messages: +The following is followed just by an offset, for use in error messages: -META_COND_ASSERT (?(?assertion) META_COND_DEFINE (?(DEFINE) In fact, META_COND_ASSERT is used for any group starting (?( that does not diff --git a/src/pcre2_compile.c b/src/pcre2_compile.c index 2519147..2482f48 100644 --- a/src/pcre2_compile.c +++ b/src/pcre2_compile.c @@ -856,6 +856,7 @@ for (;;) case META_BIGVALUE: fprintf(stderr, "META_BIGVALUE %.8x", *pptr++); break; case META_CIRCUMFLEX: fprintf(stderr, "META_CIRCUMFLEX"); break; + case META_COND_ASSERT: fprintf(stderr, "META_COND_ASSERT"); break; case META_DOLLAR: fprintf(stderr, "META_DOLLAR"); break; case META_DOT: fprintf(stderr, "META_DOT"); break; case META_ASTERISK: fprintf(stderr, "META *"); break; @@ -949,12 +950,6 @@ for (;;) fprintf(stderr, "%zd", offset); break; - case META_COND_ASSERT: - fprintf(stderr, "META_COND_ASSERT offset="); - GETOFFSET(offset, pptr); - fprintf(stderr, "%zd", offset); - break; - case META_COND_VERSION: fprintf(stderr, "META (?(VERSION%s", (*pptr++ == 0)? "=" : ">="); fprintf(stderr, "%d.", *pptr++); @@ -2189,12 +2184,12 @@ while (ptr < ptrend) PCRE2_SPTR tempptr; PCRE2_SPTR thisptr; PCRE2_SIZE offset; - + if (parsed_pattern >= parsed_pattern_end) { errorcode = ERR63; /* Internal error (parsed pattern overflow) */ - goto FAILED; - } + goto FAILED; + } if (nest_depth > cb->cx->parens_nest_limit) { @@ -2368,6 +2363,42 @@ while (ptr < ptrend) parsed_pattern, cb); } + /* If expect_cond_assert is 2, we have just passed (?( and are expecting an + assertion, possibly preceded by a callout. If the value is 1, we have just + had the callout and expect an assertion. There must be at least 3 more + characters in all cases. We know that the current character is an opening + parenthesis, as otherwise we wouldn't be here. Note that expect_cond_assert + may be negative, since all callouts just decrement it. */ + + if (expect_cond_assert > 0) + { + BOOL ok = ptrend - ptr >= 3 && ptr[0] == CHAR_QUESTION_MARK; + if (ok) switch(ptr[1]) + { + case CHAR_C: + ok = expect_cond_assert == 2; + break; + + case CHAR_EQUALS_SIGN: + case CHAR_EXCLAMATION_MARK: + break; + + case CHAR_LESS_THAN_SIGN: + ok = ptr[2] == CHAR_EQUALS_SIGN || ptr[2] == CHAR_EXCLAMATION_MARK; + break; + + default: + ok = FALSE; + } + + if (!ok) + { + ptr--; /* Adjust error offset */ + errorcode = ERR28; + goto FAILED; + } + } + /* Remember whether we are expecting a conditional assertion, and set the default for this item. */ @@ -3443,7 +3474,7 @@ while (ptr < ptrend) ptr = startptr; /* To give a more useful message */ goto FAILED; } - if (*ptr == delimiter && (++ptr >= ptrend || *ptr != delimiter)) + if (*ptr == delimiter && (++ptr >= ptrend || *ptr != delimiter)) break; } @@ -3519,18 +3550,16 @@ while (ptr < ptrend) nest_depth++; /* If the next character is ? there must be an assertion next (optionally - preceded by a callout). We do not check this here, but instead we just - preserve the offset so that the later check can give a sensible error - message. Pull back the pointer to the start of the assertion (or - callout), and set expect_cond_assert to 2. If this is still greater than - zero (callouts decrement it) when the next assertion is read, it will be - marked as a condition that must not be repeated. */ + preceded by a callout). We do not check this here, but instead we set + expect_cond_assert to 2. If this is still greater than zero (callouts + decrement it) when the next assertion is read, it will be marked as a + condition that must not be repeated. A value greater than zero also + causes checking that an assertion (possibly with callout) follows. */ if (*ptr == CHAR_QUESTION_MARK) { *parsed_pattern++ = META_COND_ASSERT; - offset = (PCRE2_SIZE)(--ptr - cb->start_pattern - 2); - PUTOFFSET(offset, parsed_pattern); + ptr--; /* Pull pointer back to the opening parenthesis. */ expect_cond_assert = 2; break; /* End of conditional */ } @@ -3902,6 +3931,11 @@ parsed_pattern = manage_callouts(ptr, &previous_callout, options, /* Terminate the parsed pattern, then return success if all groups are closed. Otherwise we have unclosed parentheses. */ +if (parsed_pattern >= parsed_pattern_end) + { + errorcode = ERR63; /* Internal error (parsed pattern overflow) */ + goto FAILED; + } *parsed_pattern = META_END; if (nest_depth == 0) return 0; @@ -5806,23 +5840,10 @@ for (;; pptr++) pptr += 3; goto GROUP_PROCESS; - /* The condition is alleged to be an assertion, possibly preceded by a - callout, because it's not one of the others, and began with (?(?. This is - where the check for the next thing being an assertion (with optional - callout) is done. */ + /* The condition is an assertion, possibly preceded by a callout. */ case META_COND_ASSERT: bravalue = OP_COND; - GETPLUSOFFSET(offset, pptr); - i = (pptr[1] == META_CALLOUT_NUMBER)? 5 : - (pptr[1] == META_CALLOUT_STRING)? (5 + SIZEOFFSET) : 1; - if (META_CODE(pptr[i]) < META_LOOKAHEAD || - META_CODE(pptr[i]) > META_LOOKBEHINDNOT) - { - *errorcodeptr = ERR28; /* Assertion expected */ - cb->erroroffset = offset + 2; /* Point after initial (? */ - return FALSE; - } goto GROUP_PROCESS; @@ -8563,7 +8584,7 @@ for (;; pptr++) goto CHECK_GROUP; case META_COND_ASSERT: - pptr += 1 + SIZEOFFSET; + pptr += 1; goto CHECK_GROUP; case META_COND_VERSION: @@ -8733,6 +8754,7 @@ for (pptr = cb->parsed_pattern; *pptr != META_END; pptr++) case META_CLASS_END: case META_CLASS_NOT: case META_COMMIT: + case META_COND_ASSERT: case META_DOLLAR: case META_DOT: case META_FAIL: @@ -8753,7 +8775,6 @@ for (pptr = cb->parsed_pattern; *pptr != META_END; pptr++) case META_THEN: break; - case META_COND_ASSERT: case META_RECURSE: pptr += SIZEOFFSET; break; @@ -9178,8 +9199,8 @@ if (parsed_size_needed >= PARSED_PATTERN_DEFAULT_SIZE) } cb.parsed_pattern = heap_parsed_pattern; } -cb.parsed_pattern_end = cb.parsed_pattern + parsed_size_needed + 1; - +cb.parsed_pattern_end = cb.parsed_pattern + parsed_size_needed + 1; + /* Do the parsing scan. */ errorcode = parse_regex(ptr, cb.external_options, &has_lookbehind, &cb); @@ -9569,7 +9590,7 @@ if ((re->overall_options & PCRE2_NO_START_OPTIMIZE) == 0 && goto HAD_CB_ERROR; } -/* Control ends up here in all cases. When running under valgrind, make a +/* Control ends up here in all cases. When running under valgrind, make a pattern's terminating zero defined again. If memory was obtained for the parsed version of the pattern, free it before returning. Also free the list of named groups if a larger one had to be obtained, and likewise the group information diff --git a/testdata/testinput2 b/testdata/testinput2 index 2d65700..159ab99 100644 --- a/testdata/testinput2 +++ b/testdata/testinput2 @@ -4912,4 +4912,8 @@ a)"xI \=get=i00000000000000000000000000000000 \=get=i2345678901234567890123456789012,get=i1245678901234567890123456789012 +"(?(?C))" + +/(?(?(?(?(?(?))))))/ + # End of testinput2 diff --git a/testdata/testoutput18 b/testdata/testoutput18 index e2eb009..51c7d21 100644 --- a/testdata/testoutput18 +++ b/testdata/testoutput18 @@ -145,7 +145,7 @@ Failed: POSIX code 9: bad escape sequence at offset 4 Failed: POSIX code 11: unbalanced () at offset 6 "(?(?C))" -Failed: POSIX code 3: pattern error at offset 2 +Failed: POSIX code 3: pattern error at offset 6 /abcd/substitute_extended ** Ignored with POSIX interface: substitute_extended diff --git a/testdata/testoutput2 b/testdata/testoutput2 index 71358cc..7d026dd 100644 --- a/testdata/testoutput2 +++ b/testdata/testoutput2 @@ -556,7 +556,7 @@ Failed: error 128 at offset 2: assertion expected after (?( or (?(?C) Failed: error 115 at offset 3: reference to non-existent subpattern /(?(?