[Rpm-maint] [rpm-software-management/rpm] Avoid out-of-bounds pointer arithmetic in dataLength() (#1626)

[Demi Marie Obenour]

@DemiMarie commented on this pull request.



> @@ -474,8 +474,8 @@ static int dataLength(rpm_tagtype_t type, rpm_constdata_t p, rpm_count_t count,
     default:
 	if (typeSizes[type] == -1)
 	    return -1;
-	length = typeSizes[(type & 0xf)] * count;
-	if (length < 0 || (se && (s + length) > se))
+	length = typeSizes[type] * count;

Good idea.

> @@ -474,8 +474,8 @@ static int dataLength(rpm_tagtype_t type, rpm_constdata_t p, rpm_count_t count,
     default:
 	if (typeSizes[type] == -1)
 	    return -1;
-	length = typeSizes[(type & 0xf)] * count;
-	if (length < 0 || (se && (s + length) > se))
+	length = typeSizes[type] * count;
+	if (length < 0 || (se && length > se - s))

Will do at the top of the function.  Since this is always a programming error (unless `se` is `NULL`), is it okay if I just call `abort()`?  Also, I would prefer to cast to `uintptr_t` first, so compilers don’t do anything sneaky.

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