Issue #19537 has been updated by jeremyevans0 (Jeremy Evans).
Status changed from Open to Closed
Fixed in commit:a1c2c274eebcc2a5275b677ebf94a8dbff380770
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Bug #19537: Regexp caching algorithm since v3.2.0 causes invalid memory access
https://bugs.ruby-lang.org/issues/19537#change-105083
* Author: jj1uzh (Futa Miyachi)
* Status: Closed
* Priority: Normal
* Assignee: make_now_just (Hiroya Fujinami)
* ruby -v: ruby 3.3.0dev (2023-03-17T09:50:55Z master c65d7b4bea) [x86_64-linux]
* Backport: 2.7: UNKNOWN, 3.0: UNKNOWN, 3.1: UNKNOWN, 3.2: UNKNOWN
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Some types of regular expressions causes invalid memory access on `#match`. Length of
strings to match does not matter.
For example, for regex `/^([ab]{1,3})(a?)*$/`, `"aac"` can crash ruby.
This bug may be caused in caching algorithm since v3.2.0.
v3.1.3 is safe as far as I checked.
Environments:
Linux 6.2.6-arch1-1 x86-64, 16GB RAM
Reproduce Process:
```
$> ruby -e 'p /^([ab]{1,3})(a?)*$/.match "aac"'
-e:1: [BUG] Segmentation fault at 0x0000560315993d90
ruby 3.3.0dev (2023-03-17T09:50:55Z master c65d7b4bea) [x86_64-linux]
...
```
Whole output is attached as output.txt.
Note that result may be `nil` correctly sometimes.
Part of backtrace:
```
#5 0x000055ff30b71ecb in sigsegv (sig=11, info=0x55ff31bd0e70, ctx=0x55ff31bd0d40) at
../signal.c:964
#6 <signal handler called>
#7 reset_match_cache (num_cache_table=<optimized out>, num_cache_size=3,
table=0x55ff31e2d930, match_cache=0x55ff31e2aec0 "\300\f", pos=2,
pend=<optimized out>, pbegin=0x55ff31dc7202 ">\030",
reg=0x55ff31e199b0) at ../regexec.c:1292
#8 match_at (reg=reg@entry=0x55ff31e199b0, str=str@entry=0x7fb176c7f148 "aac",
end=<optimized out>, end@entry=0x7fb176c7f14b "",
sstart=sstart@entry=0x7fb176c7f148 "aac", sprev=<optimized out>,
msa=msa@entry=0x7ffe40153d30)
at ../regexec.c:3486
```
---Files--------------------------------
output.txt (17.4 KB)
ruby-19537.patch (1.77 KB)
--
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