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From 72859f25cb799ba4ac0b532c59bd01be70950f00 Mon Sep 17 00:00:00 2001
From: Phil Sutter <psutter@redhat.com>
Date: Fri, 15 Mar 2019 17:51:28 +0100
Subject: [PATCH] libiptc: Avoid side-effect in memset() calls
Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=1525980
Upstream Status: iptables commit e6f986762667e
commit e6f986762667ee2b2d61e7978d460f28916158a3
Author: Phil Sutter <phil@nwl.cc>
Date: Mon Sep 10 23:35:14 2018 +0200
libiptc: Avoid side-effect in memset() calls
These calls to memset() are passed a length argument which exceeds
t->target.u.user.name's length by one byte and hence overwrite
t->target.u.user.revision as well (relying upon no padding to happen
between both).
Avoid this obscure behaviour by passing the correct field size and
explicitly overwriting 'revision' field.
Signed-off-by: Phil Sutter <phil@nwl.cc>
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Phil Sutter <psutter@redhat.com>
---
libiptc/libiptc.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/libiptc/libiptc.c b/libiptc/libiptc.c
index d2427c16a5254..4c0fbd5d7e68c 100644
--- a/libiptc/libiptc.c
+++ b/libiptc/libiptc.c
@@ -1115,8 +1115,9 @@ static inline int iptcc_compile_rule (struct xtc_handle *h, STRUCT_REPLACE *repl
STRUCT_STANDARD_TARGET *t;
t = (STRUCT_STANDARD_TARGET *)GET_TARGET(r->entry);
/* memset for memcmp convenience on delete/replace */
- memset(t->target.u.user.name, 0, FUNCTION_MAXNAMELEN);
+ memset(t->target.u.user.name, 0, XT_EXTENSION_MAXNAMELEN);
strcpy(t->target.u.user.name, STANDARD_TARGET);
+ t->target.u.user.revision = 0;
/* Jumps can only happen to builtin chains, so we
* can safely assume that they always have a header */
t->verdict = r->jump->head_offset + IPTCB_CHAIN_START_SIZE;
@@ -1676,8 +1677,9 @@ iptcc_standard_map(struct rule_head *r, int verdict)
return 0;
}
/* memset for memcmp convenience on delete/replace */
- memset(t->target.u.user.name, 0, FUNCTION_MAXNAMELEN);
+ memset(t->target.u.user.name, 0, XT_EXTENSION_MAXNAMELEN);
strcpy(t->target.u.user.name, STANDARD_TARGET);
+ t->target.u.user.revision = 0;
t->verdict = verdict;
r->type = IPTCC_R_STANDARD;
--
2.21.0