| msg44054 - (view) |
Author: Atsuo Ishimoto (ishimoto) * |
Date: 2003-06-17 16:53 |
| With this script, re reads from an address beyond the end of the string. >>> import re >>> r = re.compile(r"\b1") >>> print r.search('a', 1) See assert() in the attached patch to see where incorrect memory reading occurs. This patch looks fix the problem, but I'm not sure this is correct answer. |
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| msg44055 - (view) |
Author: Martin v. Löwis (loewis) *  |
Date: 2003-06-21 13:30 |
| Logged In: YES user_id=21627 Gustavo, can your review this code? |
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| msg44056 - (view) |
Author: Gustavo Niemeyer (niemeyer) * |
Date: 2003-06-21 23:28 |
| Logged In: YES user_id=7887 Atsuo, can you please describe what problem you're trying to fix!? In other words, can you provide some code which breaks SRE? Your assertion doesn't seem to make sense in this place, since having ptr outside the boundaries of beginning/end *is* accepted. Notice how "ptr < state->end" is checked before using ptr[0]. I'm closing this bug as invalid. If you have something you belive to prove there's a bug in this place, please reopen this bug. Thank you very much for taking the time to fill this bug. |
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| msg44057 - (view) |
Author: Atsuo Ishimoto (ishimoto) * |
Date: 2003-06-22 02:14 |
| Logged In: YES user_id=463672 Sorry for my lack of infomation. While ptr outside the boundaries is legal, but fetching from there is not. One example of problem is using SRE for mmap object. This script causes an application error under my w2k box. open("tstfile", "wb").write('a'*4096) import mmap f = open("tstfile", "rb") xx = mmap.mmap(f.fileno(), 0, access=mmap.ACCESS_READ) import re r = re.compile(r"\b1") r.search(xx, len(xx)) |
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| msg44058 - (view) |
Author: Gustavo Niemeyer (niemeyer) * |
Date: 2003-06-22 20:33 |
| Logged In: YES user_id=7887 Now I can see the problem. The current test doesn't contemplate a broken ptr/end pair. Your code is addressing the right problem, but the right way to fix this seems to be to avoid that branch completely, unless pattern[3] > 1 (unlike the current > 0). Thank you very much for your patch and your insistence! |
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| msg44059 - (view) |
Author: Gustavo Niemeyer (niemeyer) * |
Date: 2003-06-26 14:47 |
| Logged In: YES user_id=7887 Fixed in Modules/_sre.c:2.99. Thanks! |
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| msg44060 - (view) |
Author: Neal Norwitz (nnorwitz) * |
Date: 2003-06-27 14:08 |
| Logged In: YES user_id=33168 Gustavo, can you add a test case as well? Thanks. |
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