>Number: 4104
>Category: mod_jserv
>Synopsis: Typos (& and &&) in mod_jserv.c
>Confidential: no
>Severity: non-critical
>Priority: medium
>Responsible: jserv
>State: open
>Class: sw-bug
>Submitter-Id: apache
>Arrival-Date: Tue Mar 23 09:50:00 PST 1999
>Last-Modified:
>Originator: akuchlin@cnri.reston.va.us
>Organization:
apache
>Release: 1.3.3 + 1.0b3
>Environment:
Solaris 2.6
>Description:
When trying to debug an Apache problem with Electric Fence, EF reported
an out-of-bounds access. This turned out to stem from this code in mod_jserv.c:
/* Try to find if we have a protocol://host */
for (x=0; (x<128) & (buf[x]!='\0'); x++) {
if ((buf[x]==':') & (buf[x+1]=='/') & (buf[x+2]=='/')) {
^^^^ previous line is caught by ElectricFence
if (x!=0) {
protocol=buf;
buf[x]='\0';
}
The bug is a typo, or confusion on the part of the person who wrote the code;
the bitwise operator & was used instead of the logical operator &&.
& isn't short-circuited and && is, so the above line always accesses
all of buf[x], buf[x+1], buf[x+2].
>How-To-Repeat:
Compile Apache with Electric Fence, and edit main/alloc.c to use malloc()
and free().
>Fix:
A patch that fixes the place where EF segfaults is at
ftp://starship.python.net/pub/crew/amk/new/jserv-patch
This patch does NOT fix all the typos. Do a search for '{space}&{space}'
and '{space}|{space}', and you'll find other places where bitwise operators
have been used where logical ones make more sense.
A grep through the other C files didn't turn up any problems, so mod_jserv.c
may be the only affected file.
>Audit-Trail:
>Unformatted:
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