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Posted to bugs@httpd.apache.org by bu...@apache.org on 2022/04/26 20:29:24 UTC
[Bug 66033] New: Latent read beyond bounds in ap_is_matchexp()
https://bz.apache.org/bugzilla/show_bug.cgi?id=66033
Bug ID: 66033
Summary: Latent read beyond bounds in ap_is_matchexp()
Product: Apache httpd-2
Version: 2.5-HEAD
Hardware: All
OS: All
Status: NEW
Severity: normal
Priority: P2
Component: Core
Assignee: bugs@httpd.apache.org
Reporter: generalbugs@zippenhop.com
Target Milestone: ---
An apparently-latent read-beyond-bounds bug exists in ap_is_matchexp()
(server/util.c). [1] The bug is caused by an overflow when the string being
scanned is > 0x7fffffff characters long. The offending code (from trunk) is:
252: AP_DECLARE(int) ap_is_matchexp(const char *str)
253: {
254: int x;
255:
256: for (x = 0; str[x]; x++)
257: if ((str[x] == '*') || (str[x] == '?'))
258: return 1;
259: return 0;
260: }
The problem occurs when line 256 increments |x| from 0x7fffffff (positive) to
0x80000000 (negative after overflow). At that point, 0x80000000 further reads
occur from |str-0x80000000|, |str-0x7fffffff| ... |str| (unless there is a
terminating 0 somewhere in that range). This bug can also cause an infinite
loop if there is no terminating 0 between |str| and |str+0x7fffffff|, and
between |str-0x80000000| and |str-1|.
The bug appears to be latent, at least as of httpd v.2.4.53, in which the only
uses are in push_item() (modules/generators/mod_autoindex.c) and
set_server_alias() (server/core.c).
push_item() appears to be used only with internally-generated strings derived
from the server's filesystem, and so should not be asked to handle any strings
long enough to trigger the bug.
set_server_alias() processes the "ServerAlias" directive from httpd.conf, and
so also should not be asked to handle any strings long enough to trigger the
bug.
[1] The security team asked me to file this bug publicly.
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[Bug 66033] Latent read beyond bounds in ap_is_matchexp() [zhbug_httpd_46.2]
Posted by bu...@apache.org.
https://bz.apache.org/bugzilla/show_bug.cgi?id=66033
generalbugs@zippenhop.com changed:
What |Removed |Added
----------------------------------------------------------------------------
Summary|Latent read beyond bounds |Latent read beyond bounds
|in ap_is_matchexp() |in ap_is_matchexp()
| |[zhbug_httpd_46.2]
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[Bug 66033] Latent read beyond bounds in ap_is_matchexp()
Posted by bu...@apache.org.
https://bz.apache.org/bugzilla/show_bug.cgi?id=66033
--- Comment #1 from Ruediger Pluem <rp...@apache.org> ---
Fixed in trunk as r1900306.
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[Bug 66033] Latent read beyond bounds in ap_is_matchexp()
Posted by bu...@apache.org.
https://bz.apache.org/bugzilla/show_bug.cgi?id=66033
Ruediger Pluem <rp...@apache.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Keywords| |FixedInTrunk,
| |PatchAvailable
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