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ash: [EVAL] Fix use-after-free in dotrap/evalstring

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From upstream:

    [EVAL] Fix use-after-free in dotrap/evalstring

    The function dotrap calls evalstring using the stored trap string.
    If evalstring then unsets that exact trap string then we will end
    up using freed memory.

    This patch fixes it by making evalstring always duplicate the string
    before using it.

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
This commit is contained in:
Denys Vlasenko 2016-09-28 23:02:57 +02:00
parent 7ee7c6fc20
commit 8e2bc47d62
1 changed files with 7 additions and 3 deletions
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10
shell/ash.c
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@ -1459,7 +1459,7 @@ stunalloc(void *p)
* Like strdup but works with the ash stack.
*/
static char *
ststrdup(const char *p)
sstrdup(const char *p)
{
size_t len = strlen(p) + 1;
return memcpy(stalloc(len), p, len);
@ -2514,7 +2514,7 @@ updatepwd(const char *dir)
char *cdcomppath;
const char *lim;
cdcomppath = ststrdup(dir);
cdcomppath = sstrdup(dir);
STARTSTACKSTR(new);
if (*dir != '/') {
if (curdir == nullstr)
@ -6993,7 +6993,7 @@ addfname(const char *name)
struct strlist *sp;
sp = stzalloc(sizeof(*sp));
sp->text = ststrdup(name);
sp->text = sstrdup(name);
*exparg.lastp = sp;
exparg.lastp = &sp->next;
}
@ -12221,10 +12221,12 @@ evalstring(char *s, int mask)
int skip;
// int status;
s = sstrdup(s);
setinputstring(s);
setstackmark(&smark);
skip = 0;
// status = 0;
while ((n = parsecmd(0)) != NODE_EOF) {
int i;
@ -12236,7 +12238,9 @@ evalstring(char *s, int mask)
if (skip)
break;
}
popstackmark(&smark);
popfile();
stunalloc(s);
skip &= mask;
evalskip = skip;