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Message-ID: <CAD-N9QUsM7sB9K49c_Vfq_D+zSYYU4VTLaRfnRiB1EfsmxihdQ@mail.gmail.com>
Date: Thu, 10 Jun 2021 20:15:15 +0800
From: Dongliang Mu <mudongliangabcd@...il.com>
To: Liu Shixin <liushixin2@...wei.com>
Cc: Paul Moore <paul@...l-moore.com>,
"David S. Miller" <davem@...emloft.net>,
Jakub Kicinski <kuba@...nel.org>, netdev@...r.kernel.org,
linux-security-module@...r.kernel.org,
linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH -next] netlabel: Fix memory leak in netlbl_mgmt_add_common
On Thu, Jun 10, 2021 at 6:45 PM Liu Shixin <liushixin2@...wei.com> wrote:
>
> On 2021/6/10 11:08, Dongliang Mu wrote:
> > On Thu, Jun 10, 2021 at 9:31 AM Liu Shixin <liushixin2@...wei.com> wrote:
> >> Hulk Robot reported memory leak in netlbl_mgmt_add_common.
> >> The problem is non-freed map in case of netlbl_domhsh_add() failed.
> >>
> >> BUG: memory leak
> >> unreferenced object 0xffff888100ab7080 (size 96):
> >> comm "syz-executor537", pid 360, jiffies 4294862456 (age 22.678s)
> >> hex dump (first 32 bytes):
> >> 05 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
> >> fe 00 00 00 00 00 00 00 00 00 00 00 00 00 00 01 ................
> >> backtrace:
> >> [<0000000008b40026>] netlbl_mgmt_add_common.isra.0+0xb2a/0x1b40
> >> [<000000003be10950>] netlbl_mgmt_add+0x271/0x3c0
> >> [<00000000c70487ed>] genl_family_rcv_msg_doit.isra.0+0x20e/0x320
> >> [<000000001f2ff614>] genl_rcv_msg+0x2bf/0x4f0
> >> [<0000000089045792>] netlink_rcv_skb+0x134/0x3d0
> >> [<0000000020e96fdd>] genl_rcv+0x24/0x40
> >> [<0000000042810c66>] netlink_unicast+0x4a0/0x6a0
> >> [<000000002e1659f0>] netlink_sendmsg+0x789/0xc70
> >> [<000000006e43415f>] sock_sendmsg+0x139/0x170
> >> [<00000000680a73d7>] ____sys_sendmsg+0x658/0x7d0
> >> [<0000000065cbb8af>] ___sys_sendmsg+0xf8/0x170
> >> [<0000000019932b6c>] __sys_sendmsg+0xd3/0x190
> >> [<00000000643ac172>] do_syscall_64+0x37/0x90
> >> [<000000009b79d6dc>] entry_SYSCALL_64_after_hwframe+0x44/0xae
> >>
> >> Fixes: 63c416887437 ("netlabel: Add network address selectors to the NetLabel/LSM domain mapping")
> >> Reported-by: Hulk Robot <hulkci@...wei.com>
> >> Signed-off-by: Liu Shixin <liushixin2@...wei.com>
> >> ---
> >> net/netlabel/netlabel_mgmt.c | 20 ++++++++++++++++----
> >> 1 file changed, 16 insertions(+), 4 deletions(-)
> >>
> >> diff --git a/net/netlabel/netlabel_mgmt.c b/net/netlabel/netlabel_mgmt.c
> >> index e664ab990941..e7f00c0f441e 100644
> >> --- a/net/netlabel/netlabel_mgmt.c
> >> +++ b/net/netlabel/netlabel_mgmt.c
> >> @@ -191,6 +191,12 @@ static int netlbl_mgmt_add_common(struct genl_info *info,
> >> entry->family = AF_INET;
> >> entry->def.type = NETLBL_NLTYPE_ADDRSELECT;
> >> entry->def.addrsel = addrmap;
> >> +
> >> + ret_val = netlbl_domhsh_add(entry, audit_info);
> >> + if (ret_val != 0) {
> >> + kfree(map);
> >> + goto add_free_addrmap;
> >> + }
> >> #if IS_ENABLED(CONFIG_IPV6)
> >> } else if (info->attrs[NLBL_MGMT_A_IPV6ADDR]) {
> >> struct in6_addr *addr;
> >> @@ -243,13 +249,19 @@ static int netlbl_mgmt_add_common(struct genl_info *info,
> >> entry->family = AF_INET6;
> >> entry->def.type = NETLBL_NLTYPE_ADDRSELECT;
> >> entry->def.addrsel = addrmap;
> >> +
> >> + ret_val = netlbl_domhsh_add(entry, audit_info);
> >> + if (ret_val != 0) {
> >> + kfree(map);
> >> + goto add_free_addrmap;
> >> + }
> >> #endif /* IPv6 */
> >> + } else {
> >> + ret_val = netlbl_domhsh_add(entry, audit_info);
> >> + if (ret_val != 0)
> >> + goto add_free_addrmap;
> >> }
> >>
> >> - ret_val = netlbl_domhsh_add(entry, audit_info);
> >> - if (ret_val != 0)
> >> - goto add_free_addrmap;
> >> -
> > Hi Shixin,
> >
> > I have a small suggestion about this patch: you can move the variable
> > map out of if/else if branches, like the following code snippet.
> >
> > Be aware to assign the variable map to NULL at first. Then kfree in
> > the last else branch will do nothing.
> >
> > I don't test the following diff, if there are any issues, please let me know.
> >
> > diff --git a/net/netlabel/netlabel_mgmt.c b/net/netlabel/netlabel_mgmt.c
> > index ca52f5085989..1824bcd2272b 100644
> > --- a/net/netlabel/netlabel_mgmt.c
> > +++ b/net/netlabel/netlabel_mgmt.c
> > @@ -78,6 +78,7 @@ static int netlbl_mgmt_add_common(struct genl_info *info,
> > {
> > int ret_val = -EINVAL;
> > struct netlbl_domaddr_map *addrmap = NULL;
> > + struct netlbl_domaddr4_map *map = NULL;
> > struct cipso_v4_doi *cipsov4 = NULL;
> > #if IS_ENABLED(CONFIG_IPV6)
> > struct calipso_doi *calipso = NULL;
> > @@ -147,7 +148,6 @@ static int netlbl_mgmt_add_common(struct genl_info *info,
> > if (info->attrs[NLBL_MGMT_A_IPV4ADDR]) {
> > struct in_addr *addr;
> > struct in_addr *mask;
> > - struct netlbl_domaddr4_map *map;
> >
> > addrmap = kzalloc(sizeof(*addrmap), GFP_KERNEL);
> > if (addrmap == NULL) {
> > @@ -195,7 +195,6 @@ static int netlbl_mgmt_add_common(struct genl_info *info,
> > } else if (info->attrs[NLBL_MGMT_A_IPV6ADDR]) {
> > struct in6_addr *addr;
> > struct in6_addr *mask;
> > - struct netlbl_domaddr6_map *map;
> >
> > addrmap = kzalloc(sizeof(*addrmap), GFP_KERNEL);
> > if (addrmap == NULL) {
> > @@ -247,8 +246,10 @@ static int netlbl_mgmt_add_common(struct genl_info *info,
> > }
> >
> > ret_val = netlbl_domhsh_add(entry, audit_info);
> > - if (ret_val != 0)
> > + if (ret_val != 0) {
> > + kfree(map);
> > goto add_free_addrmap;
> > + }
> >
> > return 0;
> >
> The type of map can be struct netlbl_domaddr4_map or struct netlbl_domaddr6_map
> under different conditions. It seems like I can't put them together simply.
>
Yes, you're right. It takes more code changes to handle different
types. I choose to use the generic void * pointer.
The advantage of the diff below is to improve its maintainability of
error handling. I add one additional label: add_free_map to handle the
deallocation of map.
Note that, I did not test this diff. It is only used for
clarification. And maybe the compiler complains about the usage of
void * pointer.
diff --git a/net/netlabel/netlabel_mgmt.c b/net/netlabel/netlabel_mgmt.c
index ca52f5085989..38edf170b109 100644
--- a/net/netlabel/netlabel_mgmt.c
+++ b/net/netlabel/netlabel_mgmt.c
@@ -78,6 +78,7 @@ static int netlbl_mgmt_add_common(struct genl_info *info,
{
int ret_val = -EINVAL;
struct netlbl_domaddr_map *addrmap = NULL;
+ void *map = NULL;
struct cipso_v4_doi *cipsov4 = NULL;
#if IS_ENABLED(CONFIG_IPV6)
struct calipso_doi *calipso = NULL;
@@ -147,7 +148,6 @@ static int netlbl_mgmt_add_common(struct genl_info *info,
if (info->attrs[NLBL_MGMT_A_IPV4ADDR]) {
struct in_addr *addr;
struct in_addr *mask;
- struct netlbl_domaddr4_map *map;
addrmap = kzalloc(sizeof(*addrmap), GFP_KERNEL);
if (addrmap == NULL) {
@@ -170,7 +170,7 @@ static int netlbl_mgmt_add_common(struct genl_info *info,
addr = nla_data(info->attrs[NLBL_MGMT_A_IPV4ADDR]);
mask = nla_data(info->attrs[NLBL_MGMT_A_IPV4MASK]);
- map = kzalloc(sizeof(*map), GFP_KERNEL);
+ map = kzalloc(sizeof(struct netlbl_domaddr4_map), GFP_KERNEL);
if (map == NULL) {
ret_val = -ENOMEM;
goto add_free_addrmap;
@@ -183,10 +183,8 @@ static int netlbl_mgmt_add_common(struct genl_info *info,
map->def.cipso = cipsov4;
ret_val = netlbl_af4list_add(&map->list, &addrmap->list4);
- if (ret_val != 0) {
- kfree(map);
- goto add_free_addrmap;
- }
+ if (ret_val != 0)
+ goto add_free_map;
entry->family = AF_INET;
entry->def.type = NETLBL_NLTYPE_ADDRSELECT;
@@ -218,7 +216,7 @@ static int netlbl_mgmt_add_common(struct genl_info *info,
addr = nla_data(info->attrs[NLBL_MGMT_A_IPV6ADDR]);
mask = nla_data(info->attrs[NLBL_MGMT_A_IPV6MASK]);
- map = kzalloc(sizeof(*map), GFP_KERNEL);
+ map = kzalloc(sizeof(struct netlbl_domaddr6_map), GFP_KERNEL);
if (map == NULL) {
ret_val = -ENOMEM;
goto add_free_addrmap;
@@ -235,10 +233,8 @@ static int netlbl_mgmt_add_common(struct genl_info *info,
map->def.calipso = calipso;
ret_val = netlbl_af6list_add(&map->list, &addrmap->list6);
- if (ret_val != 0) {
- kfree(map);
- goto add_free_addrmap;
- }
+ if (ret_val != 0)
+ goto add_free_map;
entry->family = AF_INET6;
entry->def.type = NETLBL_NLTYPE_ADDRSELECT;
@@ -248,10 +244,12 @@ static int netlbl_mgmt_add_common(struct genl_info *info,
ret_val = netlbl_domhsh_add(entry, audit_info);
if (ret_val != 0)
- goto add_free_addrmap;
+ goto add_free_map;
return 0;
+add_free_map:
+ kfree(map);
add_free_addrmap:
kfree(addrmap);
add_doi_put_def:
> Thanks,
> >
> >
> >
> >> return 0;
> >>
> >> add_free_addrmap:
> >> --
> >> 2.18.0.huawei.25
> >>
> > .
> >
>
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