3.16.66-rc1 review patch. If anyone has any objections, please let me know.
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From: Liping Zhang liping.zhang@spreadtrum.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@spreadtrum.com Signed-off-by: Pablo Neira Ayuso pablo@netfilter.org Signed-off-by: Ben Hutchings ben@decadent.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);