Date: Tue, 10 Aug 2010 22:45:59 +0000 (UTC) From: Jilles Tjoelker <jilles@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r211155 - in head: bin/sh tools/regression/bin/sh/expansion Message-ID: <201008102245.o7AMjxIs056806@svn.freebsd.org>
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Author: jilles Date: Tue Aug 10 22:45:59 2010 New Revision: 211155 URL: http://svn.freebsd.org/changeset/base/211155 Log: sh: Fix heap-based buffer overflow in pathname generation. The buffer for generated pathnames could be too small in some cases. It happened to be always at least PATH_MAX long, so there was never an overflow if the resulting pathnames would be usable. This bug may be abused if a script subjects input from an untrusted source to pathname generation, which a bad idea anyhow. Most shell scripts do not work on untrusted data. secteam@ says no advisory is necessary. PR: bin/148733 Reported by: Changming Sun snnn119 at gmail com MFC after: 10 days Added: head/tools/regression/bin/sh/expansion/pathname3.0 (contents, props changed) Modified: head/bin/sh/expand.c Modified: head/bin/sh/expand.c ============================================================================== --- head/bin/sh/expand.c Tue Aug 10 19:50:51 2010 (r211154) +++ head/bin/sh/expand.c Tue Aug 10 22:45:59 2010 (r211155) @@ -1082,8 +1082,8 @@ ifsbreakup(char *string, struct arglist * should be escapes. The results are stored in the list exparg. */ -STATIC char *expdir; - +STATIC char expdir[PATH_MAX]; +#define expdir_end (expdir + sizeof(expdir)) STATIC void expandmeta(struct strlist *str, int flag __unused) @@ -1106,14 +1106,7 @@ expandmeta(struct strlist *str, int flag } savelastp = exparg.lastp; INTOFF; - if (expdir == NULL) { - int i = strlen(str->text); - expdir = ckmalloc(i < 2048 ? 2048 : i); /* XXX */ - } - expmeta(expdir, str->text); - ckfree(expdir); - expdir = NULL; INTON; if (exparg.lastp == savelastp) { /* @@ -1202,6 +1195,8 @@ expmeta(char *enddir, char *name) *enddir++ = *p; if (*p == '\0') break; + if (enddir == expdir_end) + return; } if (metaflag == 0 || lstat(expdir, &statb) >= 0) addfname(expdir); @@ -1216,6 +1211,8 @@ expmeta(char *enddir, char *name) if (*p == CTLESC) p++; *enddir++ = *p++; + if (enddir == expdir_end) + return; } } if (enddir == expdir) { @@ -1249,15 +1246,17 @@ expmeta(char *enddir, char *name) if (dp->d_name[0] == '.' && ! matchdot) continue; if (patmatch(start, dp->d_name, 0)) { - if (atend) { - scopy(dp->d_name, enddir); + if (enddir + dp->d_namlen + 1 > expdir_end) + continue; + memcpy(enddir, dp->d_name, dp->d_namlen + 1); + if (atend) addfname(expdir); - } else { - for (p = enddir, q = dp->d_name; - (*p++ = *q++) != '\0';) + else { + if (enddir + dp->d_namlen + 2 > expdir_end) continue; - p[-1] = '/'; - expmeta(p, endname); + enddir[dp->d_namlen] = '/'; + enddir[dp->d_namlen + 1] = '\0'; + expmeta(enddir + dp->d_namlen + 1, endname); } } } Added: head/tools/regression/bin/sh/expansion/pathname3.0 ============================================================================== --- /dev/null 00:00:00 1970 (empty, because file is newly added) +++ head/tools/regression/bin/sh/expansion/pathname3.0 Tue Aug 10 22:45:59 2010 (r211155) @@ -0,0 +1,29 @@ +# $FreeBSD$ + +v=12345678 +v=$v$v$v$v +v=$v$v$v$v +v=$v$v$v$v +v=$v$v$v$v +v=$v$v$v$v +# 8192 bytes +v=${v##???} +[ /*/$v = "/*/$v" ] || exit 1 + +s=//// +s=$s$s$s$s +s=$s$s$s$s +s=$s$s$s$s +s=$s$s$s$s +# 1024 bytes +s=${s##??????????} +[ /var/empt[y]/$s/$v = "/var/empt[y]/$s/$v" ] || exit 2 +while [ ${#s} -lt 1034 ]; do + set -- /.${s}et[c] + [ ${#s} -gt 1018 ] || [ "$1" = /.${s}etc ] || exit 3 + set -- /.${s}et[c]/ + [ ${#s} -gt 1017 ] || [ "$1" = /.${s}etc/ ] || exit 4 + set -- /.${s}et[c]/. + [ ${#s} -gt 1016 ] || [ "$1" = /.${s}etc/. ] || exit 5 + s=$s/ +done
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