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fix resource exhaustion and zero-word cases in wordexp 

when WRDE_NOSPACE is returned, the we_wordv and we_wordc members must
be valid, because the interface contract allows them to return partial
results.

in the case of zero results (due either to resource exhaustion or a
zero-word input) the we_wordv array still should contain a terminating
null pointer and the initial we_offs null pointers. this is impossible
on resource exhaustion, so a correct application must presumably check
for a null pointer in we_wordv; POSIX however seems to ignore the
issue. the previous code may have crashed under this situation.
This commit is contained in:
Rich Felker 2013-11-22 15:48:24 -05:00
parent d8f1908b82
commit 8253f59eae
1 changed files with 18 additions and 8 deletions
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24
src/misc/wordexp.c
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@ -82,20 +82,20 @@ static int do_wordexp(const char *s, wordexp_t *we, int flags)
i = wc;
if (flags & WRDE_DOOFFS) {
if (we->we_offs > SIZE_MAX/sizeof(void *)/4)
return WRDE_NOSPACE;
goto nospace;
i += we->we_offs;
} else {
we->we_offs = 0;
}
if (pipe(p) < 0) return WRDE_NOSPACE;
if (pipe(p) < 0) goto nospace;
__block_all_sigs(&set);
pid = fork();
__restore_sigs(&set);
if (pid < 0) {
close(p[0]);
close(p[1]);
return WRDE_NOSPACE;
goto nospace;
}
if (!pid) {
dup2(p[1], 1);
@ -113,7 +113,7 @@ static int do_wordexp(const char *s, wordexp_t *we, int flags)
close(p[0]);
kill(pid, SIGKILL);
waitpid(pid, &status, 0);
return WRDE_NOSPACE;
goto nospace;
}
l = wv ? i+1 : 0;
@ -142,14 +142,24 @@ static int do_wordexp(const char *s, wordexp_t *we, int flags)
while ((waitpid(pid, &status, 0) < 0 && errno == EINTR)
|| !WIFEXITED(status));
if (!wv) wv = calloc(i+1, sizeof *wv);
we->we_wordv = wv;
we->we_wordc = i;
for (i=we->we_offs; i; i--)
if (flags & WRDE_DOOFFS) {
if (wv) for (i=we->we_offs; i; i--)
we->we_wordv[i-1] = 0;
if (flags & WRDE_DOOFFS) we->we_wordc -= we->we_offs;
we->we_wordc -= we->we_offs;
}
return err;
nospace:
if (!(flags & WRDE_APPEND)) {
we->we_wordc = 0;
we->we_wordv = 0;
}
return WRDE_NOSPACE;
}
int wordexp(const char *restrict s, wordexp_t *restrict we, int flags)