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Message-ID: <lsq.1556377989.283493004@decadent.org.uk>
Date: Sat, 27 Apr 2019 16:13:09 +0100
From: Ben Hutchings <ben@...adent.org.uk>
To: linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC: akpm@...ux-foundation.org, Denis Kirjanov <kda@...ux-powerpc.org>,
"Pablo Neira Ayuso" <pablo@...filter.org>,
"Liping Zhang" <liping.zhang@...eadtrum.com>
Subject: [PATCH 3.16 156/202] netfilter: nft_compat: fix crash when
related match/target module is removed
3.16.66-rc1 review patch. If anyone has any objections, please let me know.
------------------
From: Liping Zhang <liping.zhang@...eadtrum.com>
commit 4b512e1c1f8de6b9ceb796ecef8658e0a083cab7 upstream.
We "cache" the loaded match/target modules and reuse them, but when the
modules are removed, we still point to them. Then we may end up with
invalid memory references when using iptables-compat to add rules later.
Input the following commands will reproduce the kernel crash:
# iptables-compat -A INPUT -j LOG
# iptables-compat -D INPUT -j LOG
# rmmod xt_LOG
# iptables-compat -A INPUT -j LOG
BUG: unable to handle kernel paging request at ffffffffa05a9010
IP: [<ffffffff813f783e>] strcmp+0xe/0x30
Call Trace:
[<ffffffffa05acc43>] nft_target_select_ops+0x83/0x1f0 [nft_compat]
[<ffffffffa058a177>] nf_tables_expr_parse+0x147/0x1f0 [nf_tables]
[<ffffffffa058e541>] nf_tables_newrule+0x301/0x810 [nf_tables]
[<ffffffff8141ca00>] ? nla_parse+0x20/0x100
[<ffffffffa057fa8f>] nfnetlink_rcv+0x33f/0x53d [nfnetlink]
[<ffffffffa057f94b>] ? nfnetlink_rcv+0x1fb/0x53d [nfnetlink]
[<ffffffff817116b8>] netlink_unicast+0x178/0x220
[<ffffffff81711a5b>] netlink_sendmsg+0x2fb/0x3a0
[<ffffffff816b7fc8>] sock_sendmsg+0x38/0x50
[<ffffffff816b8a7e>] ___sys_sendmsg+0x28e/0x2a0
[<ffffffff816bcb7e>] ? release_sock+0x1e/0xb0
[<ffffffff81804ac5>] ? _raw_spin_unlock_bh+0x35/0x40
[<ffffffff816bcbe2>] ? release_sock+0x82/0xb0
[<ffffffff816b93d4>] __sys_sendmsg+0x54/0x90
[<ffffffff816b9422>] SyS_sendmsg+0x12/0x20
[<ffffffff81805172>] entry_SYSCALL_64_fastpath+0x1a/0xa9
So when nobody use the related match/target module, there's no need to
"cache" it. And nft_[match|target]_release are useless anymore, remove
them.
Signed-off-by: Liping Zhang <liping.zhang@...eadtrum.com>
Signed-off-by: Pablo Neira Ayuso <pablo@...filter.org>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
net/netfilter/nft_compat.c | 43 ++++++++++++++++++--------------------
1 file changed, 20 insertions(+), 23 deletions(-)
--- a/net/netfilter/nft_compat.c
+++ b/net/netfilter/nft_compat.c
@@ -22,6 +22,20 @@
#include <asm/uaccess.h> /* for set_fs */
#include <net/netfilter/nf_tables.h>
+struct nft_xt {
+ struct list_head head;
+ struct nft_expr_ops ops;
+ unsigned int refcnt;
+};
+
+static void nft_xt_put(struct nft_xt *xt)
+{
+ if (--xt->refcnt == 0) {
+ list_del(&xt->head);
+ kfree(xt);
+ }
+}
+
union nft_entry {
struct ipt_entry e4;
struct ip6t_entry e6;
@@ -208,6 +222,7 @@ nft_target_destroy(const struct nft_ctx
if (par.target->destroy != NULL)
par.target->destroy(&par);
+ nft_xt_put(container_of(expr->ops, struct nft_xt, ops));
module_put(target->me);
}
@@ -408,6 +423,7 @@ nft_match_destroy(const struct nft_ctx *
if (par.match->destroy != NULL)
par.match->destroy(&par);
+ nft_xt_put(container_of(expr->ops, struct nft_xt, ops));
module_put(me);
}
@@ -606,11 +622,6 @@ static const struct nfnetlink_subsystem
static LIST_HEAD(nft_match_list);
-struct nft_xt {
- struct list_head head;
- struct nft_expr_ops ops;
-};
-
static struct nft_expr_type nft_match_type;
static bool nft_match_cmp(const struct xt_match *match,
@@ -646,6 +657,7 @@ nft_match_select_ops(const struct nft_ct
if (!try_module_get(match->me))
return ERR_PTR(-ENOENT);
+ nft_match->refcnt++;
return &nft_match->ops;
}
}
@@ -659,6 +671,7 @@ nft_match_select_ops(const struct nft_ct
if (nft_match == NULL)
return ERR_PTR(-ENOMEM);
+ nft_match->refcnt = 1;
nft_match->ops.type = &nft_match_type;
nft_match->ops.size = NFT_EXPR_SIZE(XT_ALIGN(match->matchsize) +
nft_compat_match_offset(match));
@@ -674,14 +687,6 @@ nft_match_select_ops(const struct nft_ct
return &nft_match->ops;
}
-static void nft_match_release(void)
-{
- struct nft_xt *nft_match, *tmp;
-
- list_for_each_entry_safe(nft_match, tmp, &nft_match_list, head)
- kfree(nft_match);
-}
-
static struct nft_expr_type nft_match_type __read_mostly = {
.name = "match",
.select_ops = nft_match_select_ops,
@@ -727,6 +732,7 @@ nft_target_select_ops(const struct nft_c
if (!try_module_get(target->me))
return ERR_PTR(-ENOENT);
+ nft_target->refcnt++;
return &nft_target->ops;
}
}
@@ -740,6 +746,7 @@ nft_target_select_ops(const struct nft_c
if (nft_target == NULL)
return ERR_PTR(-ENOMEM);
+ nft_target->refcnt = 1;
nft_target->ops.type = &nft_target_type;
nft_target->ops.size = NFT_EXPR_SIZE(XT_ALIGN(target->targetsize) +
nft_compat_target_offset(target));
@@ -755,14 +762,6 @@ nft_target_select_ops(const struct nft_c
return &nft_target->ops;
}
-static void nft_target_release(void)
-{
- struct nft_xt *nft_target, *tmp;
-
- list_for_each_entry_safe(nft_target, tmp, &nft_target_list, head)
- kfree(nft_target);
-}
-
static struct nft_expr_type nft_target_type __read_mostly = {
.name = "target",
.select_ops = nft_target_select_ops,
@@ -805,8 +804,6 @@ static void __exit nft_compat_module_exi
nfnetlink_subsys_unregister(&nfnl_compat_subsys);
nft_unregister_expr(&nft_target_type);
nft_unregister_expr(&nft_match_type);
- nft_match_release();
- nft_target_release();
}
MODULE_ALIAS_NFNL_SUBSYS(NFNL_SUBSYS_NFT_COMPAT);
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