[syzbot] memory leak in ip_vs_add_service

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syzbot

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May 24, 2021, 10:33:25 AMMay 24
to core...@netfilter.org, da...@davemloft.net, f...@strlen.de, ho...@verge.net.au, j...@ssi.bg, kad...@netfilter.org, ku...@kernel.org, linux-...@vger.kernel.org, lvs-...@vger.kernel.org, net...@vger.kernel.org, netfilt...@vger.kernel.org, pa...@netfilter.org, syzkall...@googlegroups.com
Hello,

syzbot found the following issue on:

HEAD commit: c3d0e3fd Merge tag 'fs.idmapped.mount_setattr.v5.13-rc3' o..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=148d0bd7d00000
kernel config: https://syzkaller.appspot.com/x/.config?x=ae7b129a135ab06b
dashboard link: https://syzkaller.appspot.com/bug?extid=e562383183e4b1766930
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=15585a4bd00000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=13900753d00000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+e56238...@syzkaller.appspotmail.com

BUG: memory leak
unreferenced object 0xffff888115227800 (size 512):
comm "syz-executor263", pid 8658, jiffies 4294951882 (age 12.560s)
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:
[<ffffffff83977188>] kmalloc include/linux/slab.h:556 [inline]
[<ffffffff83977188>] kzalloc include/linux/slab.h:686 [inline]
[<ffffffff83977188>] ip_vs_add_service+0x598/0x7c0 net/netfilter/ipvs/ip_vs_ctl.c:1343
[<ffffffff8397d770>] do_ip_vs_set_ctl+0x810/0xa40 net/netfilter/ipvs/ip_vs_ctl.c:2570
[<ffffffff838449a8>] nf_setsockopt+0x68/0xa0 net/netfilter/nf_sockopt.c:101
[<ffffffff839ae4e9>] ip_setsockopt+0x259/0x1ff0 net/ipv4/ip_sockglue.c:1435
[<ffffffff839fa03c>] raw_setsockopt+0x18c/0x1b0 net/ipv4/raw.c:857
[<ffffffff83691f20>] __sys_setsockopt+0x1b0/0x360 net/socket.c:2117
[<ffffffff836920f2>] __do_sys_setsockopt net/socket.c:2128 [inline]
[<ffffffff836920f2>] __se_sys_setsockopt net/socket.c:2125 [inline]
[<ffffffff836920f2>] __x64_sys_setsockopt+0x22/0x30 net/socket.c:2125
[<ffffffff84350efa>] do_syscall_64+0x3a/0xb0 arch/x86/entry/common.c:47
[<ffffffff84400068>] entry_SYSCALL_64_after_hwframe+0x44/0xae



---
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See https://goo.gl/tpsmEJ for more information about syzbot.
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syzbot can test patches for this issue, for details see:
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Julian Anastasov

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May 24, 2021, 3:04:52 PMMay 24
to syzbot, syzkall...@googlegroups.com
0001-ipvs-ignore-IP_VS_SVC_F_HASHED-flag-when-adding-servic.txt

syzbot

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May 24, 2021, 3:22:09 PMMay 24
to j...@ssi.bg, syzkall...@googlegroups.com
Hello,

syzbot has tested the proposed patch and the reproducer did not trigger any issue:

Reported-and-tested-by: syzbot+e56238...@syzkaller.appspotmail.com

Tested on:

commit: 4dd649d1 NFC: nfcmrvl: fix kernel-doc syntax in file headers
git tree: net
kernel config: https://syzkaller.appspot.com/x/.config?x=89a71983bb63ddf9
dashboard link: https://syzkaller.appspot.com/bug?extid=e562383183e4b1766930
compiler:
patch: https://syzkaller.appspot.com/x/patch.diff?x=13f1de37d00000

Note: testing is done by a robot and is best-effort only.

Xin Long

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Jun 2, 2021, 5:39:12 PMJun 2
to syzbot, core...@netfilter.org, davem, Florian Westphal, Simon Horman, Julian Anastasov, kad...@netfilter.org, Jakub Kicinski, LKML, lvs-...@vger.kernel.org, network dev, netfilt...@vger.kernel.org, Pablo Neira Ayuso, syzkaller-bugs
do_ip_vs_set_ctl() allows users to add svc with the flags field set.
when IP_VS_SVC_F_HASHED is used, and in ip_vs_svc_hash()
called ip_vs_add_service() will trigger the err msg:

IPVS: ip_vs_svc_hash(): request for already hashed, called from
do_ip_vs_set_ctl+0x810/0xa40

and the svc allocated will leak.

so fix it by mask the flags with ~IP_VS_SVC_F_HASHED in
ip_vs_copy_usvc_compat(), while at it also remove the unnecessary
flag IP_VS_SVC_F_HASHED set in ip_vs_edit_service().

diff --git a/net/netfilter/ipvs/ip_vs_ctl.c b/net/netfilter/ipvs/ip_vs_ctl.c
index d45dbcba8b49..f09a443c9ec0 100644
--- a/net/netfilter/ipvs/ip_vs_ctl.c
+++ b/net/netfilter/ipvs/ip_vs_ctl.c
@@ -1497,7 +1497,6 @@ ip_vs_edit_service(struct ip_vs_service *svc,
struct ip_vs_service_user_kern *u)
/*
* Set the flags and timeout value
*/
- svc->flags = u->flags | IP_VS_SVC_F_HASHED;
svc->timeout = u->timeout * HZ;
svc->netmask = u->netmask;

@@ -2430,7 +2429,7 @@ static void ip_vs_copy_usvc_compat(struct
ip_vs_service_user_kern *usvc,
/* Deep copy of sched_name is not needed here */
usvc->sched_name = usvc_compat->sched_name;

- usvc->flags = usvc_compat->flags;
+ usvc->flags = usvc_compat->flags & ~IP_VS_SVC_F_HASHED;
usvc->timeout = usvc_compat->timeout;
usvc->netmask = usvc_compat->netmask;

Julian Anastasov

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Jun 3, 2021, 1:32:17 PMJun 3
to Xin Long, syzbot, core...@netfilter.org, Simon Horman, LKML, lvs-...@vger.kernel.org, network dev, netfilt...@vger.kernel.org, syzkaller-bugs

Hello,
The net tree already contains fix for this problem.

Regards

--
Julian Anastasov <j...@ssi.bg>

Xin Long

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Jun 3, 2021, 1:35:47 PMJun 3
to Julian Anastasov, syzbot, core...@netfilter.org, Simon Horman, LKML, lvs-...@vger.kernel.org, network dev, netfilt...@vger.kernel.org, syzkaller-bugs
good, thanks for the info, :-)
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