Date: Mon, 17 Sep 2001 08:34:32 -0700 (PDT) From: Jim Bauer <jfbauer@nfr.com> To: freebsd-gnats-submit@FreeBSD.org Subject: misc/30631: readdir_r() SEGV on large directories Message-ID: <200109171534.f8HFYWf70187@freefall.freebsd.org>
index | next in thread | raw e-mail
>Number: 30631
>Category: misc
>Synopsis: readdir_r() SEGV on large directories
>Confidential: no
>Severity: non-critical
>Priority: medium
>Responsible: freebsd-bugs
>State: open
>Quarter:
>Keywords:
>Date-Required:
>Class: sw-bug
>Submitter-Id: current-users
>Arrival-Date: Mon Sep 17 08:40:00 PDT 2001
>Closed-Date:
>Last-Modified:
>Originator: Jim Bauer
>Release: 4.2-RELEASE and 4.3-RELEASE
>Organization:
NFR Security Inc
>Environment:
FreeBSD heraus.nfr.net 4.2-RELEASE FreeBSD 4.2-RELEASE #0: Wed Sep 5 10:02:48 EDT 2001 jfbauer@heraus.nfr.net:/usr/src/sys/compile/GENERIC.SMP i386
>Description:
Under some circumstances, readdir_r() tries to memcpy too much
data from the buffer opendir() malloced thus reading beyond the
end of the buffer. The problem only seems to occur if "-pthread"
is given on the compile command line.
>How-To-Repeat:
/*
* To repeat:
* cc .... -pthread
*
* d="d.$$"; mkdir $d
* i=1; while [ $i -lt 245 ]; do touch $d/f.$i; i=`expr $i + 1`; done
*
* ./a.out $d
*
* When I run this it outputs....
* file = f.1
* file = f.2
* ...
* file = f.240
* Segmentation fault (core dumped)
*/
#include <stdio.h>
#include <dirent.h>
int main(int argc, char **argv) {
DIR *dir;
struct dirent entry;
struct dirent *result;
char *dirname = ".";
if (argc > 2) {
fprintf(stderr, "Usage %s [dir]\n", argv[0]);
exit(1);
}
if (argc == 2)
dirname = argv[1];
dir = opendir(dirname);
if (dir == NULL) {
perror("opendir");
exit(1);
}
while (readdir_r(dir, &entry, &result) == 0 && result != NULL) {
printf("file = %s\n", entry.d_name);
}
}
>Fix:
Changing the memcpy() in readdir_r() to only copy d_namlen bytes
instead of sizeof(struct dirent) should fix the problem, but this
has not been tested.
>Release-Note:
>Audit-Trail:
>Unformatted:
To Unsubscribe: send mail to majordomo@FreeBSD.org
with "unsubscribe freebsd-bugs" in the body of the message
help
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?200109171534.f8HFYWf70187>