Guard against out-of-bounds memory access when parsing LIMIT_HEAP et al #463
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Patterns passed to pcre2_compile are not guaranteed to be
null-terminated. Also, it can happen that there is an invalid
pattern like this:
(*LIMIT_HEAP=123
If the next byte of memory after the end of the pattern happens
to be a digit, it will be parsed as part of the limit value. Or,
if the next byte is a right parenthesis character, it will be taken
as the end of the (*LIMIT_HEAP=nnn) construct.
This will result in `skipatstart` being larger than `patlen`, which
will result in underflow and an erroneous call to malloc requesting
a huge number of bytes.
alexdowad
commented
Sep 6, 2024
| @@ -111,10 +111,10 @@ Minimum depth limit = 10 | |||
| 3: ee | |||
|
|
|||
| /(*LIMIT_MATCH=12bc)abc/ | |||
| Failed: error 160 at offset 17: (*VERB) not recognized or malformed | |||
| Failed: error 160 at offset 16: (*VERB) not recognized or malformed | |||
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This is more logical now: the first bad character in the LIMIT_MATCH construct is at offset 16, not offset 17.
carenas
added a commit
to carenas/pcre2
that referenced
this pull request
Sep 21, 2024
As reported recently by ef218fb (Guard against out-of-bounds memory access when parsing LIMIT_HEAP et al (PCRE2Project#463), 2024-09-07), a malformed pattern could result in reading 1 byte past its end. Fix a similar issue that affects all VERBs and add test cases to ensure the original bug and all its siblings are no longer an issue. While at it fix the wording of the related documentation.
carenas
added a commit
to carenas/pcre2
that referenced
this pull request
Sep 22, 2024
As reported recently by ef218fb (Guard against out-of-bounds memory access when parsing LIMIT_HEAP et al (PCRE2Project#463), 2024-09-07), a malformed pattern could result in reading 1 byte past its end. Fix a similar issue that affects all VERBs and add test cases to ensure the original bug and all its siblings are no longer an issue. While at it fix the wording of the related documentation.
PhilipHazel
pushed a commit
that referenced
this pull request
Sep 22, 2024
As reported recently by ef218fb (Guard against out-of-bounds memory access when parsing LIMIT_HEAP et al (#463), 2024-09-07), a malformed pattern could result in reading 1 byte past its end. Fix a similar issue that affects all VERBs and add test cases to ensure the original bug and all its siblings are no longer an issue. While at it fix the wording of the related documentation.
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While fuzzing PCRE2, I found a case in which
pcre2_compilemay incorrectly read past the end of the pattern string which it is given. Here are the details:Patterns passed to
pcre2_compileare not guaranteed to be null-terminated. Also, it can happen that there is an invalid pattern like this:If the next byte of memory after the end of the pattern happens to be a digit, it will be parsed as part of the limit value. Or, if the next byte is a right parenthesis character, it will be taken as the end of the
(*LIMIT_HEAP=nnn)construct.This will result in
skipatstartbeing larger thanpatlen, which will result in underflow and an erroneous call to malloc requesting a huge number of bytes.