[git commit] ash: make ${v:N:M} more robust for very large M by clamping to MIN/MAX_INT
Denys Vlasenko
vda.linux at googlemail.com
Wed Jan 10 12:22:25 UTC 2018
commit: https://git.busybox.net/busybox/commit/?id=baa41c785551ae0580526298aa6fadf4534fc8c0
branch: https://git.busybox.net/busybox/commit/?id=refs/heads/master
Before this patch, "${v:2:0x100000001}" = "${v:2:1}",
and similarly, constructs like "${v:2:9999999999}" may give wrong result
due to int overflows.
function old new delta
substr_atoi - 43 +43
Signed-off-by: Denys Vlasenko <vda.linux at googlemail.com>
---
shell/ash.c | 38 +++++++++++++++++++++++++-------------
1 file changed, 25 insertions(+), 13 deletions(-)
diff --git a/shell/ash.c b/shell/ash.c
index 83a8e77..a7f330c 100644
--- a/shell/ash.c
+++ b/shell/ash.c
@@ -5780,6 +5780,26 @@ ash_arith(const char *s)
return result;
}
#endif
+#if BASH_SUBSTR
+# if ENABLE_FEATURE_SH_MATH
+static int substr_atoi(const char *s)
+{
+ arith_t t = ash_arith(s);
+ if (sizeof(t) > sizeof(int)) {
+ /* clamp very large or very large negative nums for ${v:N:M}:
+ * else "${v:0:0x100000001}" would work as "${v:0:1}"
+ */
+ if (t > INT_MAX)
+ t = INT_MAX;
+ if (t < INT_MIN)
+ t = INT_MIN;
+ }
+ return t;
+}
+# else
+# define substr_atoi(s) number(s)
+# endif
+#endif
/*
* expandarg flags
@@ -6816,13 +6836,10 @@ subevalvar(char *p, char *varname, int strloc, int subtype,
loc = str = stackblock() + strloc;
-# if !ENABLE_FEATURE_SH_MATH
-# define ash_arith number
-# endif
/* Read POS in ${var:POS:LEN} */
colon = strchr(loc, ':');
if (colon) *colon = '\0';
- pos = ash_arith(loc);
+ pos = substr_atoi(loc);
if (colon) *colon = ':';
/* Read LEN in ${var:POS:LEN} */
@@ -6830,7 +6847,6 @@ subevalvar(char *p, char *varname, int strloc, int subtype,
/* *loc != '\0', guaranteed by parser */
if (quotes) {
char *ptr;
-
/* Adjust the length by the number of escapes */
for (ptr = startp; ptr < (str - 1); ptr++) {
if ((unsigned char)*ptr == CTLESC) {
@@ -6842,19 +6858,15 @@ subevalvar(char *p, char *varname, int strloc, int subtype,
orig_len = len;
if (*loc++ == ':') {
/* ${var::LEN} */
- len = ash_arith(loc);
+ len = substr_atoi(loc);
} else {
/* Skip POS in ${var:POS:LEN} */
len = orig_len;
- while (*loc && *loc != ':') {
+ while (*loc && *loc != ':')
loc++;
- }
- if (*loc++ == ':') {
- len = ash_arith(loc);
- }
+ if (*loc++ == ':')
+ len = substr_atoi(loc);
}
-# undef ash_arith
-
if (pos < 0) {
/* ${VAR:$((-n)):l} starts n chars from the end */
pos = orig_len + pos;
More information about the busybox-cvs
mailing list