busybox: Backport CVE-2022-48174 fix

There is a stack overflow vulnerability in ash.c:6030 in busybox before
1.35. In the environment of Internet of Vehicles, this vulnerability can
be executed from command to arbitrary code execution.

https://nvd.nist.gov/vuln/detail/CVE-2022-48174

CVE: CVE-2022-48174
Signed-off-by: Marek Vasut <marex@denx.de>
Signed-off-by: Steve Sakoman <steve@sakoman.com>

2 files changed, 83 insertions, 0 deletions

diff --git a/meta/recipes-core/busybox/busybox/CVE-2022-48174.patch b/meta/recipes-core/busybox/busybox/CVE-2022-48174.patch
new file mode 100644
index 0000000000..dfba2a7e0f
--- /dev/null
+++ b/meta/recipes-core/busybox/busybox/CVE-2022-48174.patch
@@ -0,0 +1,82 @@
+From c18ebf861528ef24958dd99a146482d2a40014c7 Mon Sep 17 00:00:00 2001
+From: Denys Vlasenko <vda.linux@googlemail.com>
+Date: Mon, 12 Jun 2023 17:48:47 +0200
+Subject: [PATCH] shell: avoid segfault on ${0::0/0~09J}. Closes 15216
+
+function                                             old     new   delta
+evaluate_string                                     1011    1053     +42
+
+CVE: CVE-2022-48174
+Upstream-Status: Backport [d417193cf37ca1005830d7e16f5fa7e1d8a44209]
+Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
+---
+ shell/math.c | 39 +++++++++++++++++++++++++++++++++++----
+ 1 file changed, 35 insertions(+), 4 deletions(-)
+
+diff --git a/shell/math.c b/shell/math.c
+index af1ab55c0..79824e81f 100644
+--- a/shell/math.c
++++ b/shell/math.c
+@@ -578,6 +578,28 @@ static arith_t strto_arith_t(const char *nptr, char **endptr)
+ # endif
+ #endif
+ 
++//TODO: much better estimation than expr_len/2? Such as:
++//static unsigned estimate_nums_and_names(const char *expr)
++//{
++//	unsigned count = 0;
++//	while (*(expr = skip_whitespace(expr)) != '\0') {
++//		const char *p;
++//		if (isdigit(*expr)) {
++//			while (isdigit(*++expr))
++//				continue;
++//			count++;
++//			continue;
++//		}
++//		p = endofname(expr);
++//		if (p != expr) {
++//			expr = p;
++//			count++;
++//			continue;
++//		}
++//	}
++//	return count;
++//}
++
+ static arith_t FAST_FUNC
+ evaluate_string(arith_state_t *math_state, const char *expr)
+ {
+@@ -585,10 +607,12 @@ evaluate_string(arith_state_t *math_state, const char *expr)
+ 	const char *errmsg;
+ 	const char *start_expr = expr = skip_whitespace(expr);
+ 	unsigned expr_len = strlen(expr) + 2;
+-	/* Stack of integers */
+-	/* The proof that there can be no more than strlen(startbuf)/2+1
+-	 * integers in any given correct or incorrect expression
+-	 * is left as an exercise to the reader. */
++	/* Stack of integers/names */
++	/* There can be no more than strlen(startbuf)/2+1
++	 * integers/names in any given correct or incorrect expression.
++	 * (modulo "09v09v09v09v09v" case,
++	 * but we have code to detect that early)
++	 */
+ 	var_or_num_t *const numstack = alloca((expr_len / 2) * sizeof(numstack[0]));
+ 	var_or_num_t *numstackptr = numstack;
+ 	/* Stack of operator tokens */
+@@ -657,6 +681,13 @@ evaluate_string(arith_state_t *math_state, const char *expr)
+ 			numstackptr->var = NULL;
+ 			errno = 0;
+ 			numstackptr->val = strto_arith_t(expr, (char**) &expr);
++			/* A number can't be followed by another number, or a variable name.
++			 * We'd catch this later anyway, but this would require numstack[]
++			 * to be twice as deep to handle strings where _every_ char is
++			 * a new number or name. Example: 09v09v09v09v09v09v09v09v09v
++			 */
++			if (isalnum(*expr) || *expr == '_')
++				goto err;
+ 			if (errno)
+ 				numstackptr->val = 0; /* bash compat */
+ 			goto num;
+-- 
+2.40.1
+
diff --git a/meta/recipes-core/busybox/busybox_1.31.1.bb b/meta/recipes-core/busybox/busybox_1.31.1.bb
index d062f0f7dd..94aa1467df 100644
--- a/meta/recipes-core/busybox/busybox_1.31.1.bb
+++ b/meta/recipes-core/busybox/busybox_1.31.1.bb
@@ -55,6 +55,7 @@ SRC_URI = "https://busybox.net/downloads/busybox-${PV}.tar.bz2;name=tarball \
            file://CVE-2021-42374.patch \
            file://CVE-2021-42376.patch \
            file://CVE-2021-423xx-awk.patch \
+           file://CVE-2022-48174.patch \
            file://0001-libbb-sockaddr2str-ensure-only-printable-characters-.patch \
            file://0002-nslookup-sanitize-all-printed-strings-with-printable.patch \
            "