memory leak in pfkey_xfrm_policy2msg_prep

memory leak in pfkey_xfrm_policy2msg_prep

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit:    4dde821e Merge tag 'xfs-5.2-fixes-1' of git://git.kernel.o..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=176fcb8aa00000
kernel config:  https://syzkaller.appspot.com/x/.config?x=61dd9e15a761691d
dashboard link: https://syzkaller.appspot.com/bug?extid=4f0529365f7f2208d9f0
compiler:       gcc (GCC) 9.0.0 20181231 (experimental)
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=179bd84ca00000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=124004a2a00000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+4f0529365f7f2208d9f0@syzkaller.appspotmail.com

ed '10.128.1.31' (ECDSA) to the list of known hosts.
executing program
executing program
executing program
BUG: memory leak
unreferenced object 0xffff888126306200 (size 224):
   comm "softirq", pid 0, jiffies 4294944009 (age 13.770s)
   hex dump (first 32 bytes):
     00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
     00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
   backtrace:
     [<00000000dbfa6a53>] kmemleak_alloc_recursive  
include/linux/kmemleak.h:55 [inline]
     [<00000000dbfa6a53>] slab_post_alloc_hook mm/slab.h:439 [inline]
     [<00000000dbfa6a53>] slab_alloc_node mm/slab.c:3269 [inline]
     [<00000000dbfa6a53>] kmem_cache_alloc_node+0x153/0x2a0 mm/slab.c:3579
     [<00000000963741ad>] __alloc_skb+0x6e/0x210 net/core/skbuff.c:198
     [<000000006fea5c94>] alloc_skb include/linux/skbuff.h:1058 [inline]
     [<000000006fea5c94>] pfkey_xfrm_policy2msg_prep+0x2a/0x50  
net/key/af_key.c:2054
     [<0000000069777b1f>] dump_sp net/key/af_key.c:2692 [inline]
     [<0000000069777b1f>] dump_sp+0x64/0x110 net/key/af_key.c:2682
     [<000000006ac00402>] xfrm_policy_walk+0xd4/0x230  
net/xfrm/xfrm_policy.c:1841
     [<00000000f7271518>] pfkey_dump_sp+0x2a/0x30 net/key/af_key.c:2719
     [<00000000652376b8>] pfkey_do_dump+0x3b/0xe0 net/key/af_key.c:289
     [<000000006ac94254>] pfkey_spddump+0x81/0xb0 net/key/af_key.c:2746
     [<000000006bacb6ca>] pfkey_process+0x28a/0x2d0 net/key/af_key.c:2836
     [<0000000037320f8e>] pfkey_sendmsg+0x188/0x2e0 net/key/af_key.c:3675
     [<0000000026dba653>] sock_sendmsg_nosec net/socket.c:652 [inline]
     [<0000000026dba653>] sock_sendmsg+0x54/0x70 net/socket.c:671
     [<000000004931d76f>] ___sys_sendmsg+0x393/0x3c0 net/socket.c:2292
     [<00000000ca71443f>] __sys_sendmsg+0x80/0xf0 net/socket.c:2330
     [<000000005d43081c>] __do_sys_sendmsg net/socket.c:2339 [inline]
     [<000000005d43081c>] __se_sys_sendmsg net/socket.c:2337 [inline]
     [<000000005d43081c>] __x64_sys_sendmsg+0x23/0x30 net/socket.c:2337
     [<000000005fdf8054>] do_syscall_64+0x76/0x1a0  
arch/x86/entry/common.c:301
     [<000000000c8dd476>] entry_SYSCALL_64_after_hwframe+0x44/0xa9



---
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[PATCH net] af_key: fix leaks in key_pol_get_resp and dump_sp.

[Jeremy Sowden]

In both functions, if pfkey_xfrm_policy2msg failed we leaked the newly
allocated sk_buff.  Free it on error.

Fixes: 55569ce256ce ("Fix conversion between IPSEC_MODE_xxx and XFRM_MODE_xxx.")
Reported-by: syzbot+4f0529365f7f2208d9f0@syzkaller.appspotmail.com
Signed-off-by: Jeremy Sowden <jeremy@azazel.net>
---
 net/key/af_key.c | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/net/key/af_key.c b/net/key/af_key.c
index 4af1e1d60b9f..4cca397fd032 100644
--- a/net/key/af_key.c
+++ b/net/key/af_key.c
@@ -2442,8 +2442,10 @@ static int key_pol_get_resp(struct sock *sk, struct xfrm_policy *xp, const struc
 		goto out;
 	}
 	err = pfkey_xfrm_policy2msg(out_skb, xp, dir);
-	if (err < 0)
-		goto out;
+	if (err < 0) {
+		kfree_skb(out_skb);
+		return err;
+	}
 
 	out_hdr = (struct sadb_msg *) out_skb->data;
 	out_hdr->sadb_msg_version = hdr->sadb_msg_version;
@@ -2694,8 +2696,10 @@ static int dump_sp(struct xfrm_policy *xp, int dir, int count, void *ptr)
 		return PTR_ERR(out_skb);
 
 	err = pfkey_xfrm_policy2msg(out_skb, xp, dir);
-	if (err < 0)
+	if (err < 0) {
+		kfree_skb(out_skb);
 		return err;
+	}
 
 	out_hdr = (struct sadb_msg *) out_skb->data;
 	out_hdr->sadb_msg_version = pfk->dump.msg_version;
-- 
2.20.1

[PATCH net v2] af_key: fix leaks in key_pol_get_resp and dump_sp.

[Jeremy Sowden]

In both functions, if pfkey_xfrm_policy2msg failed we leaked the newly
allocated sk_buff.  Free it on error.

Fixes: 55569ce256ce ("Fix conversion between IPSEC_MODE_xxx and XFRM_MODE_xxx.")
Reported-by: syzbot+4f0529365f7f2208d9f0@syzkaller.appspotmail.com
Signed-off-by: Jeremy Sowden <jeremy@azazel.net>
---
Since v1.

  * Changed return back to goto in key_pol_get_resp.

 net/key/af_key.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/net/key/af_key.c b/net/key/af_key.c
index 4af1e1d60b9f..51c0f10bb131 100644
--- a/net/key/af_key.c
+++ b/net/key/af_key.c
@@ -2442,8 +2442,10 @@ static int key_pol_get_resp(struct sock *sk, struct xfrm_policy *xp, const struc
 		goto out;
 	}
 	err = pfkey_xfrm_policy2msg(out_skb, xp, dir);
-	if (err < 0)
+	if (err < 0) {
+		kfree_skb(out_skb);
 		goto out;
+	}
 
 	out_hdr = (struct sadb_msg *) out_skb->data;
 	out_hdr->sadb_msg_version = hdr->sadb_msg_version;
@@ -2694,8 +2696,10 @@ static int dump_sp(struct xfrm_policy *xp, int dir, int count, void *ptr)
 		return PTR_ERR(out_skb);
 
 	err = pfkey_xfrm_policy2msg(out_skb, xp, dir);
-	if (err < 0)
+	if (err < 0) {
+		kfree_skb(out_skb);
 		return err;
+	}
 
 	out_hdr = (struct sadb_msg *) out_skb->data;
 	out_hdr->sadb_msg_version = pfk->dump.msg_version;
-- 
2.20.1

Re: [PATCH net v2] af_key: fix leaks in key_pol_get_resp and dump_sp.

[Steffen Klassert]

On Sat, May 25, 2019 at 07:09:35PM +0100, Jeremy Sowden wrote:
> In both functions, if pfkey_xfrm_policy2msg failed we leaked the newly
> allocated sk_buff.  Free it on error.
> 
> Fixes: 55569ce256ce ("Fix conversion between IPSEC_MODE_xxx and XFRM_MODE_xxx.")
> Reported-by: syzbot+4f0529365f7f2208d9f0@syzkaller.appspotmail.com
> Signed-off-by: Jeremy Sowden <jeremy@azazel.net>

Applied, thanks Jeremy!