external/cde
1
0
Fork 0
mirror of git://git.code.sf.net/p/cdesktopenv/code synced 2025-03-09 15:50:02 +00:00
Code Issues Releases Wiki Activity

Patch vulnerability CVE-2019-14868

Browse source 
Certain environment variables were interpreted as arithmetic
expressions on startup, leading to code injection.

Ref.:
https://bugzilla.redhat.com/show_bug.cgi?id=1757324
c7de8b6412

(cherry picked from commit ee6b001d0611ad2e00b6da2c2b42051995c0a678)
This commit is contained in:
Martijn Dekker 2020-05-21 14:27:51 +02:00
parent c1dae413d2
commit 593a5a8b7f
3 changed files with 57 additions and 14 deletions
Download patch file Download diff file Expand all files Collapse all files

4
NEWS
View file

@ -10,6 +10,10 @@ Any uppercase BUG_* names are modernish shell bug IDs.
'<#pattern'. The bug was caused by out-of-sync streams.
Details and discussion: https://github.com/att/ast/issues/61
- Patched code injection vulerability CVE-2019-14868. As a result, you can
no longer use expressions in imported numeric environment variables; only
integer literals are allowed.
2020-05-20:
- Fix BUG_ISSETLOOP. Expansions like ${var+set} remained static when used

43
src/cmd/ksh93/sh/arith.c
View file

@ -513,21 +513,36 @@ Sfdouble_t sh_strnum(register const char *str, char** ptr, int mode)
char base=(shp->inarith?0:10), *last;
if(*str==0)
{
if(ptr)
*ptr = (char*)str;
return(0);
d = 0.0;
last = (char*)str;
} else {
errno = 0;
d = strtonll(str,&last,&base,-1);
if (*last && !shp->inarith && sh_isstate(SH_INIT)) {
/* This call is to handle "base#value" literals if we're importing untrusted env vars. */
errno = 0;
d = strtonll(str, &last, NULL, -1);
}
if(*last || errno)
{
if (sh_isstate(SH_INIT)) {
/*
* Initializing means importing untrusted env vars. The string does not appear to be
* a recognized numeric literal, so give up. We can't safely call strval(), because
* that allows arbitrary expressions, causing security vulnerability CVE-2019-14868.
*/
d = 0.0;
} else {
if(!last || *last!='.' || last[1]!='.')
d = strval(shp,str,&last,arith,mode);
if(!ptr && *last && mode>0)
errormsg(SH_DICT,ERROR_exit(1),e_lexbadchar,*last,str);
}
} else if (!d && *str=='-') {
d = -0.0;
}
}
errno = 0;
d = strtonll(str,&last,&base,-1);
if(*last || errno)
{
if(!last || *last!='.' || last[1]!='.')
d = strval(shp,str,&last,arith,mode);
if(!ptr && *last && mode>0)
errormsg(SH_DICT,ERROR_exit(1),e_lexbadchar,*last,str);
}
else if (!d && *str=='-')
d = -0.0;
if(ptr)
*ptr = last;
return(d);

24
src/cmd/ksh93/tests/variables.sh
View file

@ -737,5 +737,29 @@ actual=$(_test_v var)
actual=$(_test_v IFS)
[[ "$actual" = "$expect" ]] || err_exit "[[ -v IFS ]] expansion fails in loops (expected '$expect', got '$actual')"
# ======
# Verify that importing untrusted environment variables does not allow evaluating
# arbitrary expressions, but does recognize all integer literals recognized by ksh.
expect=8
actual=$(env SHLVL='7' "$SHELL" -c 'echo $SHLVL')
[[ $actual == $expect ]] || err_exit "decimal int literal not recognized (expected '$expect', got '$actual')"
expect=14
actual=$(env SHLVL='013' "$SHELL" -c 'echo $SHLVL')
[[ $actual == $expect ]] || err_exit "leading zeros int literal not recognized (expected '$expect', got '$actual')"
expect=4
actual=$(env SHLVL='2#11' "$SHELL" -c 'echo $SHLVL')
[[ $actual == $expect ]] || err_exit "base#value int literal not recognized (expected '$expect', got '$actual')"
expect=12
actual=$(env SHLVL='16#B' "$SHELL" -c 'echo $SHLVL')
[[ $actual == $expect ]] || err_exit "base#value int literal not recognized (expected '$expect', got '$actual')"
expect=1
actual=$(env SHLVL="2#11+x[\$(env echo Exploited vuln CVE-2019-14868 >&2)0]" "$SHELL" -c 'echo $SHLVL' 2>&1)
[[ $actual == $expect ]] || err_exit "expression allowed on env var import (expected '$expect', got '$actual')"
# ======
exit $((Errors<125?Errors:125))