File 0003-awk-fix-use-after-free-CVE-2023-42363.patch of Package busybox.43070
From 03c751b2e800f8ca369719bc8745b9d754983e4e Mon Sep 17 00:00:00 2001
From: Natanael Copa <ncopa@alpinelinux.org>
Date: Mon, 20 May 2024 17:55:28 +0200
Subject: [PATCH 3/7] awk: fix use after free (CVE-2023-42363)
function old new delta
evaluate 3377 3385 +8
Fixes https://bugs.busybox.net/show_bug.cgi?id=15865
Signed-off-by: Natanael Copa <ncopa@alpinelinux.org>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
(cherry picked from commit fb08d43d44d1fea1f741fafb9aa7e1958a5f69aa)
---
editors/awk.c | 21 +++++++++++++--------
1 file changed, 13 insertions(+), 8 deletions(-)
diff --git a/editors/awk.c b/editors/awk.c
index 40873519e..c844232ec 100644
--- a/editors/awk.c
+++ b/editors/awk.c
@@ -2918,19 +2918,14 @@ static var *evaluate(node *op, var *res)
/* yes, remember where Fields[] is */
old_Fields_ptr = Fields;
}
- if (opinfo & OF_STR1) {
- L.s = getvar_s(L.v);
- debug_printf_eval("L.s:'%s'\n", L.s);
- }
if (opinfo & OF_NUM1) {
L_d = getvar_i(L.v);
debug_printf_eval("L_d:%f\n", L_d);
}
}
- /* NB: Must get string/numeric values of L (done above)
- * _before_ evaluate()'ing R.v: if both L and R are $NNNs,
- * and right one is large, then L.v points to Fields[NNN1],
- * second evaluate() reallocates and moves (!) Fields[],
+ /* NB: if both L and R are $NNNs, and right one is large,
+ * then at this pint L.v points to Fields[NNN1], second
+ * evaluate() below reallocates and moves (!) Fields[],
* R.v points to Fields[NNN2] but L.v now points to freed mem!
* (Seen trying to evaluate "$444 $44444")
*/
@@ -2950,6 +2945,16 @@ static var *evaluate(node *op, var *res)
debug_printf_eval("R.s:'%s'\n", R.s);
}
}
+ /* Get L.s _after_ R.v is evaluated: it may have realloc'd L.v
+ * so we must get the string after "old_Fields_ptr" correction
+ * above. Testcase: x = (v = "abc", gsub("b", "X", v));
+ */
+ if (opinfo & OF_RES1) {
+ if (opinfo & OF_STR1) {
+ L.s = getvar_s(L.v);
+ debug_printf_eval("L.s:'%s'\n", L.s);
+ }
+ }
debug_printf_eval("switch(0x%x)\n", XC(opinfo & OPCLSMASK));
switch (XC(opinfo & OPCLSMASK)) {
--
2.52.0
