diff mbox series

[master,3/3] busybox: fix CVE-2026-38755

Message ID 20261105073452.890881-3-dkelaiya@cisco.com
State New
Headers show
Series [master,1/3] busybox: fix CVE-2026-38752 | expand

Commit Message

Darsh Kelaiya -X (dkelaiya - E INFOCHIPS PRIVATE LIMITED at Cisco) Nov. 5, 2026, 7:34 a.m. UTC 
From: Darsh Kelaiya <dkelaiya@cisco.com>

This patch applies the upstream fix shown in [1].
The advisory identifying the fix is referenced in [2].

[1] https://lists.busybox.net/pipermail/busybox/2026-June/092354.html
[2] https://nvd.nist.gov/vuln/detail/cve-2026-38755

Signed-off-by: Darsh Kelaiya <dkelaiya@cisco.com>
---
 .../busybox/busybox/CVE-2026-38755.patch      | 71 +++++++++++++++++++
 meta/recipes-core/busybox/busybox_1.38.0.bb   |  1 +
 2 files changed, 72 insertions(+)
 create mode 100644 meta/recipes-core/busybox/busybox/CVE-2026-38755.patch
diff mbox series

Patch

diff --git a/meta/recipes-core/busybox/busybox/CVE-2026-38755.patch b/meta/recipes-core/busybox/busybox/CVE-2026-38755.patch
new file mode 100644
index 0000000..d999a0c
--- /dev/null
+++ b/meta/recipes-core/busybox/busybox/CVE-2026-38755.patch
@@ -0,0 +1,71 @@ 
+From 819a0f9ba510c4d9efce0021a0357faa6257b44d Mon Sep 17 00:00:00 2001
+From: Sanghyun Park <sanghyun.park.cnu@gmail.com>
+Date: Tue, 16 Jun 2026 12:19:27 +0900
+Subject: [PATCH] ash: fix stack overflow in evalfun()
+
+Recursive shell functions can repeatedly enter evalfun() until the
+process stack is exhausted. Track active shell function calls and raise a
+normal shell error when the recursion limit is reached.
+
+The counter is decremented through the existing funcdone cleanup path so
+errors raised from inside the function body unwind it correctly.
+
+CVE: CVE-2026-38755
+Upstream-Status: Submitted [https://lists.busybox.net/pipermail/busybox/2026-June/092354.html]
+
+Signed-off-by: Sanghyun Park <sanghyun.park.cnu@gmail.com>
+Signed-off-by: Darsh Kelaiya <dkelaiya@cisco.com>
+---
+ shell/ash.c | 8 ++++++++
+ 1 file changed, 8 insertions(+)
+
+diff --git a/shell/ash.c b/shell/ash.c
+index b8ff67b..4c7c778 100644
+--- a/shell/ash.c
++++ b/shell/ash.c
+@@ -481,6 +481,7 @@ struct globals_misc {
+ 	int shlvl;
+ #define rootshell (!shlvl)
+ 	int errlinno;
++	unsigned func_depth;
+ 
+ 	char *minusc;  /* argument to -c option */
+ 
+@@ -588,6 +589,7 @@ extern struct globals_misc *BB_GLOBAL_CONST ash_ptr_to_globals_misc;
+ #define rootpid     (G_misc.rootpid    )
+ #define shlvl       (G_misc.shlvl      )
+ #define errlinno    (G_misc.errlinno   )
++#define func_depth  (G_misc.func_depth )
+ #define minusc      (G_misc.minusc     )
+ #define curdir      (G_misc.curdir     )
+ #define physdir     (G_misc.physdir    )
+@@ -10309,6 +10311,10 @@ evalfun(struct funcnode *func, int argc, char **argv, int flags)
+ 	int savefuncline;
+ 	char *savefuncname;
+ 	char *savetrap = NULL;
++	enum { MAX_ASH_FUNC_DEPTH = 1000 };
++
++	if (func_depth >= MAX_ASH_FUNC_DEPTH)
++		ash_msg_and_raise_error("function recursion limit exceeded");
+ 
+ 	if (!Eflag) {
+ 		savetrap = trap[NTRAP_ERR];
+@@ -10327,6 +10333,7 @@ evalfun(struct funcnode *func, int argc, char **argv, int flags)
+ 	exception_handler = &jmploc;
+ 	shellparam.malloced = 0;
+ 	func->count++;
++	func_depth++;
+ 	funcname = func->n.ndefun.text;
+ 	funcline = func->n.ndefun.linno;
+ 	INTON;
+@@ -10348,6 +10355,7 @@ evalfun(struct funcnode *func, int argc, char **argv, int flags)
+ 	}
+ 	funcline = savefuncline;
+ 	lineno = savelineno;
++	func_depth--;
+ 	freefunc(func);
+ 	freeparam(&shellparam);
+ 	shellparam = saveparam;
+-- 
+2.35.6
+
diff --git a/meta/recipes-core/busybox/busybox_1.38.0.bb b/meta/recipes-core/busybox/busybox_1.38.0.bb
index 108839e..2c0b415 100644
--- a/meta/recipes-core/busybox/busybox_1.38.0.bb
+++ b/meta/recipes-core/busybox/busybox_1.38.0.bb
@@ -62,6 +62,7 @@  SRC_URI = "https://busybox.net/downloads/busybox-${PV}.tar.bz2;name=tarball \
            file://CVE-2026-38752.patch \
            file://CVE-2026-38753.patch \
            file://CVE-2026-38754.patch \
+           file://CVE-2026-38755.patch \
            "
 SRC_URI:append:libc-musl = " file://musl.cfg"
 SRC_URI:append:x86-64 = " file://sha_accel.cfg"