[PATCH] alias: Fix out-of-bound access

[Herbert Xu <herbert@gondor.apana.org.au>]

Harald van Dijk <harald@gigawatt.nl> wrote:
>
> I had trusted that this "n+1: funny ksh stuff" logic which allows an 
> alias to start with = was because ksh allows this, but I tested this 
> now, it does not and I can find no evidence that it ever did. Maybe it 
> would be good to just remove this exception, or if dash wants to keep 
> it, document it as an ash extension rather than claim it as a ksh thing?

Thanks.  This patch should fix the overrun.

---8<---
Check for empty string before searching for equal sign starting at
n+1 in aliascmd.

Reported-by: Harald van Dijk <harald@gigawatt.nl>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

diff --git a/src/alias.c b/src/alias.c
index fcad43b..cee07e9 100644
--- a/src/alias.c
+++ b/src/alias.c
@@ -143,7 +143,8 @@ aliascmd(int argc, char **argv)
 		return (0);
 	}
 	while ((n = *++argv) != NULL) {
-		if ((v = strchr(n+1, '=')) == NULL) { /* n+1: funny ksh stuff */
+		/* n + 1: funny ksh stuff (from 44lite) */
+		if (!*n || !(v = strchr(n + 1, '='))) {
 			if ((ap = *__lookupalias(n)) == NULL) {
 				outfmt(out2, "%s: %s not found\n", "alias", n);
 				ret = 1;
-- 
Email: Herbert Xu <herbert@gondor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt