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* memory leak in start_sync_thread
@ 2019-05-28 18:28 syzbot
  2019-06-11  1:06 ` Eric Biggers
  0 siblings, 1 reply; 3+ messages in thread
From: syzbot @ 2019-05-28 18:28 UTC (permalink / raw)
  To: coreteam, davem, fw, horms, ja, kadlec, linux-kernel, lvs-devel,
	netdev, netfilter-devel, pablo, syzkaller-bugs, wensong

Hello,

syzbot found the following crash on:

HEAD commit:    cd6c84d8 Linux 5.2-rc2
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=132bd44aa00000
kernel config:  https://syzkaller.appspot.com/x/.config?x=64479170dcaf0e11
dashboard link: https://syzkaller.appspot.com/bug?extid=7e2e50c8adfccd2e5041
compiler:       gcc (GCC) 9.0.0 20181231 (experimental)
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=114b1354a00000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=14b7ad26a00000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+7e2e50c8adfccd2e5041@syzkaller.appspotmail.com

d started: state = MASTER, mcast_ifn = syz_tun, syncid = 0, id = 0
BUG: memory leak
unreferenced object 0xffff8881206bf700 (size 32):
   comm "syz-executor761", pid 7268, jiffies 4294943441 (age 20.470s)
   hex dump (first 32 bytes):
     00 40 7c 09 81 88 ff ff 80 45 b8 21 81 88 ff ff  .@|......E.!....
     00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
   backtrace:
     [<0000000057619e23>] kmemleak_alloc_recursive  
include/linux/kmemleak.h:55 [inline]
     [<0000000057619e23>] slab_post_alloc_hook mm/slab.h:439 [inline]
     [<0000000057619e23>] slab_alloc mm/slab.c:3326 [inline]
     [<0000000057619e23>] kmem_cache_alloc_trace+0x13d/0x280 mm/slab.c:3553
     [<0000000086ce5479>] kmalloc include/linux/slab.h:547 [inline]
     [<0000000086ce5479>] start_sync_thread+0x5d2/0xe10  
net/netfilter/ipvs/ip_vs_sync.c:1862
     [<000000001a9229cc>] do_ip_vs_set_ctl+0x4c5/0x780  
net/netfilter/ipvs/ip_vs_ctl.c:2402
     [<00000000ece457c8>] nf_sockopt net/netfilter/nf_sockopt.c:106 [inline]
     [<00000000ece457c8>] nf_setsockopt+0x4c/0x80  
net/netfilter/nf_sockopt.c:115
     [<00000000942f62d4>] ip_setsockopt net/ipv4/ip_sockglue.c:1258 [inline]
     [<00000000942f62d4>] ip_setsockopt+0x9b/0xb0 net/ipv4/ip_sockglue.c:1238
     [<00000000a56a8ffd>] udp_setsockopt+0x4e/0x90 net/ipv4/udp.c:2616
     [<00000000fa895401>] sock_common_setsockopt+0x38/0x50  
net/core/sock.c:3130
     [<0000000095eef4cf>] __sys_setsockopt+0x98/0x120 net/socket.c:2078
     [<000000009747cf88>] __do_sys_setsockopt net/socket.c:2089 [inline]
     [<000000009747cf88>] __se_sys_setsockopt net/socket.c:2086 [inline]
     [<000000009747cf88>] __x64_sys_setsockopt+0x26/0x30 net/socket.c:2086
     [<00000000ded8ba80>] do_syscall_64+0x76/0x1a0  
arch/x86/entry/common.c:301
     [<00000000893b4ac8>] entry_SYSCALL_64_after_hwframe+0x44/0xa9

BUG: memory leak
unreferenced object 0xffff8881206bf700 (size 32):
   comm "syz-executor761", pid 7268, jiffies 4294943441 (age 21.530s)
   hex dump (first 32 bytes):
     00 40 7c 09 81 88 ff ff 80 45 b8 21 81 88 ff ff  .@|......E.!....
     00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
   backtrace:
     [<0000000057619e23>] kmemleak_alloc_recursive  
include/linux/kmemleak.h:55 [inline]
     [<0000000057619e23>] slab_post_alloc_hook mm/slab.h:439 [inline]
     [<0000000057619e23>] slab_alloc mm/slab.c:3326 [inline]
     [<0000000057619e23>] kmem_cache_alloc_trace+0x13d/0x280 mm/slab.c:3553
     [<0000000086ce5479>] kmalloc include/linux/slab.h:547 [inline]
     [<0000000086ce5479>] start_sync_thread+0x5d2/0xe10  
net/netfilter/ipvs/ip_vs_sync.c:1862
     [<000000001a9229cc>] do_ip_vs_set_ctl+0x4c5/0x780  
net/netfilter/ipvs/ip_vs_ctl.c:2402
     [<00000000ece457c8>] nf_sockopt net/netfilter/nf_sockopt.c:106 [inline]
     [<00000000ece457c8>] nf_setsockopt+0x4c/0x80  
net/netfilter/nf_sockopt.c:115
     [<00000000942f62d4>] ip_setsockopt net/ipv4/ip_sockglue.c:1258 [inline]
     [<00000000942f62d4>] ip_setsockopt+0x9b/0xb0 net/ipv4/ip_sockglue.c:1238
     [<00000000a56a8ffd>] udp_setsockopt+0x4e/0x90 net/ipv4/udp.c:2616
     [<00000000fa895401>] sock_common_setsockopt+0x38/0x50  
net/core/sock.c:3130
     [<0000000095eef4cf>] __sys_setsockopt+0x98/0x120 net/socket.c:2078
     [<000000009747cf88>] __do_sys_setsockopt net/socket.c:2089 [inline]
     [<000000009747cf88>] __se_sys_setsockopt net/socket.c:2086 [inline]
     [<000000009747cf88>] __x64_sys_setsockopt+0x26/0x30 net/socket.c:2086
     [<00000000ded8ba80>] do_syscall_64+0x76/0x1a0  
arch/x86/entry/common.c:301
     [<00000000893b4ac8>] entry_SYSCALL_64_after_hwframe+0x44/0xa9

BUG: memory leak
unreferenced object 0xffff8881206bf700 (size 32):
   comm "syz-executor761", pid 7268, jiffies 4294943441 (age 22.630s)
   hex dump (first 32 bytes):
     00 40 7c 09 81 88 ff ff 80 45 b8 21 81 88 ff ff  .@|......E.!....
     00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
   backtrace:
     [<0000000057619e23>] kmemleak_alloc_recursive  
include/linux/kmemleak.h:55 [inline]
     [<0000000057619e23>] slab_post_alloc_hook mm/slab.h:439 [inline]
     [<0000000057619e23>] slab_alloc mm/slab.c:3326 [inline]
     [<0000000057619e23>] kmem_cache_alloc_trace+0x13d/0x280 mm/slab.c:3553
     [<0000000086ce5479>] kmalloc include/linux/slab.h:547 [inline]
     [<0000000086ce5479>] start_sync_thread+0x5d2/0xe10  
net/netfilter/ipvs/ip_vs_sync.c:1862
     [<000000001a9229cc>] do_ip_vs_set_ctl+0x4c5/0x780  
net/netfilter/ipvs/ip_vs_ctl.c:2402
     [<00000000ece457c8>] nf_sockopt net/netfilter/nf_sockopt.c:106 [inline]
     [<00000000ece457c8>] nf_setsockopt+0x4c/0x80  
net/netfilter/nf_sockopt.c:115
     [<00000000942f62d4>] ip_setsockopt net/ipv4/ip_sockglue.c:1258 [inline]
     [<00000000942f62d4>] ip_setsockopt+0x9b/0xb0 net/ipv4/ip_sockglue.c:1238
     [<00000000a56a8ffd>] udp_setsockopt+0x4e/0x90 net/ipv4/udp.c:2616
     [<00000000fa895401>] sock_common_setsockopt+0x38/0x50  
net/core/sock.c:3130
     [<0000000095eef4cf>] __sys_setsockopt+0x98/0x120 net/socket.c:2078
     [<000000009747cf88>] __do_sys_setsockopt net/socket.c:2089 [inline]
     [<000000009747cf88>] __se_sys_setsockopt net/socket.c:2086 [inline]
     [<000000009747cf88>] __x64_sys_setsockopt+0x26/0x30 net/socket.c:2086
     [<00000000ded8ba80>] do_syscall_64+0x76/0x1a0  
arch/x86/entry/common.c:301
     [<00000000893b4ac8>] entry_SYSCALL_64_after_hwframe+0x44/0xa9

BUG: memory leak
unreferenced object 0xffff8881206bf700 (size 32):
   comm "syz-executor761", pid 7268, jiffies 4294943441 (age 23.720s)
   hex dump (first 32 bytes):
     00 40 7c 09 81 88 ff ff 80 45 b8 21 81 88 ff ff  .@|......E.!....
     00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
   backtrace:
     [<0000000057619e23>] kmemleak_alloc_recursive  
include/linux/kmemleak.h:55 [inline]
     [<0000000057619e23>] slab_post_alloc_hook mm/slab.h:439 [inline]
     [<0000000057619e23>] slab_alloc mm/slab.c:3326 [inline]
     [<0000000057619e23>] kmem_cache_alloc_trace+0x13d/0x280 mm/slab.c:3553
     [<0000000086ce5479>] kmalloc include/linux/slab.h:547 [inline]
     [<0000000086ce5479>] start_sync_thread+0x5d2/0xe10  
net/netfilter/ipvs/ip_vs_sync.c:1862
     [<000000001a9229cc>] do_ip_vs_set_ctl+0x4c5/0x780  
net/netfilter/ipvs/ip_vs_ctl.c:2402
     [<00000000ece457c8>] nf_sockopt net/netfilter/nf_sockopt.c:106 [inline]
     [<00000000ece457c8>] nf_setsockopt+0x4c/0x80  
net/netfilter/nf_sockopt.c:115
     [<00000000942f62d4>] ip_setsockopt net/ipv4/ip_sockglue.c:1258 [inline]
     [<00000000942f62d4>] ip_setsockopt+0x9b/0xb0 net/ipv4/ip_sockglue.c:1238
     [<00000000a56a8ffd>] udp_setsockopt+0x4e/0x90 net/ipv4/udp.c:2616
     [<00000000fa895401>] sock_common_setsockopt+0x38/0x50  
net/core/sock.c:3130
     [<0000000095eef4cf>] __sys_setsockopt+0x98/0x120 net/socket.c:2078
     [<000000009747cf88>] __do_sys_setsockopt net/socket.c:2089 [inline]
     [<000000009747cf88>] __se_sys_setsockopt net/socket.c:2086 [inline]
     [<000000009747cf88>] __x64_sys_setsockopt+0x26/0x30 net/socket.c:2086
     [<00000000ded8ba80>] do_syscall_64+0x76/0x1a0  
arch/x86/entry/common.c:301
     [<00000000893b4ac8>] entry_SYSCALL_64_after_hwframe+0x44/0xa9

BUG: memory leak
unreferenced object 0xffff8881206bf700 (size 32):
   comm "syz-executor761", pid 7268, jiffies 4294943441 (age 25.770s)
   hex dump (first 32 bytes):
     00 40 7c 09 81 88 ff ff 80 45 b8 21 81 88 ff ff  .@|......E.!....
     00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
   backtrace:
     [<0000000057619e23>] kmemleak_alloc_recursive  
include/linux/kmemleak.h:55 [inline]
     [<0000000057619e23>] slab_post_alloc_hook mm/slab.h:439 [inline]
     [<0000000057619e23>] slab_alloc mm/slab.c:3326 [inline]
     [<0000000057619e23>] kmem_cache_alloc_trace+0x13d/0x280 mm/slab.c:3553
     [<0000000086ce5479>] kmalloc include/linux/slab.h:547 [inline]
     [<0000000086ce5479>] start_sync_thread+0x5d2/0xe10  
net/netfilter/ipvs/ip_vs_sync.c:1862
     [<000000001a9229cc>] do_ip_vs_set_ctl+0x4c5/0x780  
net/netfilter/ipvs/ip_vs_ctl.c:2402
     [<00000000ece457c8>] nf_sockopt net/netfilter/nf_sockopt.c:106 [inline]
     [<00000000ece457c8>] nf_setsockopt+0x4c/0x80  
net/netfilter/nf_sockopt.c:115
     [<00000000942f62d4>] ip_setsockopt net/ipv4/ip_sockglue.c:1258 [inline]
     [<00000000942f62d4>] ip_setsockopt+0x9b/0xb0 net/ipv4/ip_sockglue.c:1238
     [<00000000a56a8ffd>] udp_setsockopt+0x4e/0x90 net/ipv4/udp.c:2616
     [<00000000fa895401>] sock_common_setsockopt+0x38/0x50  
net/core/sock.c:3130
     [<0000000095eef4cf>] __sys_setsockopt+0x98/0x120 net/socket.c:2078
     [<000000009747cf88>] __do_sys_setsockopt net/socket.c:2089 [inline]
     [<000000009747cf88>] __se_sys_setsockopt net/socket.c:2086 [inline]
     [<000000009747cf88>] __x64_sys_setsockopt+0x26/0x30 net/socket.c:2086
     [<00000000ded8ba80>] do_syscall_64+0x76/0x1a0  
arch/x86/entry/common.c:301
     [<00000000893b4ac8>] entry_SYSCALL_64_after_hwframe+0x44/0xa9

BUG: memory leak
unreferenced object 0xffff8881206bf700 (size 32):
   comm "syz-executor761", pid 7268, jiffies 4294943441 (age 26.850s)
   hex dump (first 32 bytes):
     00 40 7c 09 81 88 ff ff 80 45 b8 21 81 88 ff ff  .@|......E.!....
     00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
   backtrace:
     [<0000000057619e23>] kmemleak_alloc_recursive  
include/linux/kmemleak.h:55 [inline]
     [<0000000057619e23>] slab_post_alloc_hook mm/slab.h:439 [inline]
     [<0000000057619e23>] slab_alloc mm/slab.c:3326 [inline]
     [<0000000057619e23>] kmem_cache_alloc_trace+0x13d/0x280 mm/slab.c:3553
     [<0000000086ce5479>] kmalloc include/linux/slab.h:547 [inline]
     [<0000000086ce5479>] start_sync_thread+0x5d2/0xe10  
net/netfilter/ipvs/ip_vs_sync.c:1862
     [<000000001a9229cc>] do_ip_vs_set_ctl+0x4c5/0x780  
net/netfilter/ipvs/ip_vs_ctl.c:2402
     [<00000000ece457c8>] nf_sockopt net/netfilter/nf_sockopt.c:106 [inline]
     [<00000000ece457c8>] nf_setsockopt+0x4c/0x80  
net/netfilter/nf_sockopt.c:115
     [<00000000942f62d4>] ip_setsockopt net/ipv4/ip_sockglue.c:1258 [inline]
     [<00000000942f62d4>] ip_setsockopt+0x9b/0xb0 net/ipv4/ip_sockglue.c:1238
     [<00000000a56a8ffd>] udp_setsockopt+0x4e/0x90 net/ipv4/udp.c:2616
     [<00000000fa895401>] sock_common_setsockopt+0x38/0x50  
net/core/sock.c:3130
     [<0000000095eef4cf>] __sys_setsockopt+0x98/0x120 net/socket.c:2078
     [<000000009747cf88>] __do_sys_setsockopt net/socket.c:2089 [inline]
     [<000000009747cf88>] __se_sys_setsockopt net/socket.c:2086 [inline]
     [<000000009747cf88>] __x64_sys_setsockopt+0x26/0x30 net/socket.c:2086
     [<00000000ded8ba80>] do_syscall_64+0x76/0x1a0  
arch/x86/entry/common.c:301
     [<00000000893b4ac8>] entry_SYSCALL_64_after_hwframe+0x44/0xa9

BUG: memory leak
unreferenced object 0xffff8881206bf700 (size 32):
   comm "syz-executor761", pid 7268, jiffies 4294943441 (age 27.940s)
   hex dump (first 32 bytes):
     00 40 7c 09 81 88 ff ff 80 45 b8 21 81 88 ff ff  .@|......E.!....
     00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
   backtrace:
     [<0000000057619e23>] kmemleak_alloc_recursive  
include/linux/kmemleak.h:55 [inline]
     [<0000000057619e23>] slab_post_alloc_hook mm/slab.h:439 [inline]
     [<0000000057619e23>] slab_alloc mm/slab.c:3326 [inline]
     [<0000000057619e23>] kmem_cache_alloc_trace+0x13d/0x280 mm/slab.c:3553
     [<0000000086ce5479>] kmalloc include/linux/slab.h:547 [inline]
     [<0000000086ce5479>] start_sync_thread+0x5d2/0xe10  
net/netfilter/ipvs/ip_vs_sync.c:1862
     [<000000001a9229cc>] do_ip_vs_set_ctl+0x4c5/0x780  
net/netfilter/ipvs/ip_vs_ctl.c:2402
     [<00000000ece457c8>] nf_sockopt net/netfilter/nf_sockopt.c:106 [inline]
     [<00000000ece457c8>] nf_setsockopt+0x4c/0x80  
net/netfilter/nf_sockopt.c:115
     [<00000000942f62d4>] ip_setsockopt net/ipv4/ip_sockglue.c:1258 [inline]
     [<00000000942f62d4>] ip_setsockopt+0x9b/0xb0 net/ipv4/ip_sockglue.c:1238
     [<00000000a56a8ffd>] udp_setsockopt+0x4e/0x90 net/ipv4/udp.c:2616
     [<00000000fa895401>] sock_common_setsockopt+0x38/0x50  
net/core/sock.c:3130
     [<0000000095eef4cf>] __sys_setsockopt+0x98/0x120 net/socket.c:2078
     [<000000009747cf88>] __do_sys_setsockopt net/socket.c:2089 [inline]
     [<000000009747cf88>] __se_sys_setsockopt net/socket.c:2086 [inline]
     [<000000009747cf88>] __x64_sys_setsockopt+0x26/0x30 net/socket.c:2086
     [<00000000ded8ba80>] do_syscall_64+0x76/0x1a0  
arch/x86/entry/common.c:301
     [<00000000893b4ac8>] entry_SYSCALL_64_after_hwframe+0x44/0xa9

executing program


---
This bug is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzkaller@googlegroups.com.

syzbot will keep track of this bug report. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
syzbot can test patches for this bug, for details see:
https://goo.gl/tpsmEJ#testing-patches

^ permalink raw reply	[flat|nested] 3+ messages in thread
* Re: memory leak in start_sync_thread
  2019-05-28 18:28 memory leak in start_sync_thread syzbot
@ 2019-06-11  1:06 ` Eric Biggers
  2019-06-11 19:52   ` Julian Anastasov
  0 siblings, 1 reply; 3+ messages in thread
From: Eric Biggers @ 2019-06-11  1:06 UTC (permalink / raw)
  To: syzbot
  Cc: coreteam, davem, fw, horms, ja, kadlec, linux-kernel, lvs-devel,
	netdev, netfilter-devel, pablo, syzkaller-bugs, wensong

On Tue, May 28, 2019 at 11:28:05AM -0700, syzbot wrote:
> Hello,
> 
> syzbot found the following crash on:
> 
> HEAD commit:    cd6c84d8 Linux 5.2-rc2
> git tree:       upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=132bd44aa00000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=64479170dcaf0e11
> dashboard link: https://syzkaller.appspot.com/bug?extid=7e2e50c8adfccd2e5041
> compiler:       gcc (GCC) 9.0.0 20181231 (experimental)
> syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=114b1354a00000
> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=14b7ad26a00000
> 
> IMPORTANT: if you fix the bug, please add the following tag to the commit:
> Reported-by: syzbot+7e2e50c8adfccd2e5041@syzkaller.appspotmail.com
> 
> d started: state = MASTER, mcast_ifn = syz_tun, syncid = 0, id = 0
> BUG: memory leak
> unreferenced object 0xffff8881206bf700 (size 32):
>   comm "syz-executor761", pid 7268, jiffies 4294943441 (age 20.470s)
>   hex dump (first 32 bytes):
>     00 40 7c 09 81 88 ff ff 80 45 b8 21 81 88 ff ff  .@|......E.!....
>     00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
>   backtrace:
>     [<0000000057619e23>] kmemleak_alloc_recursive
> include/linux/kmemleak.h:55 [inline]
>     [<0000000057619e23>] slab_post_alloc_hook mm/slab.h:439 [inline]
>     [<0000000057619e23>] slab_alloc mm/slab.c:3326 [inline]
>     [<0000000057619e23>] kmem_cache_alloc_trace+0x13d/0x280 mm/slab.c:3553
>     [<0000000086ce5479>] kmalloc include/linux/slab.h:547 [inline]
>     [<0000000086ce5479>] start_sync_thread+0x5d2/0xe10
> net/netfilter/ipvs/ip_vs_sync.c:1862
>     [<000000001a9229cc>] do_ip_vs_set_ctl+0x4c5/0x780
> net/netfilter/ipvs/ip_vs_ctl.c:2402
>     [<00000000ece457c8>] nf_sockopt net/netfilter/nf_sockopt.c:106 [inline]
>     [<00000000ece457c8>] nf_setsockopt+0x4c/0x80
> net/netfilter/nf_sockopt.c:115
>     [<00000000942f62d4>] ip_setsockopt net/ipv4/ip_sockglue.c:1258 [inline]
>     [<00000000942f62d4>] ip_setsockopt+0x9b/0xb0 net/ipv4/ip_sockglue.c:1238
>     [<00000000a56a8ffd>] udp_setsockopt+0x4e/0x90 net/ipv4/udp.c:2616
>     [<00000000fa895401>] sock_common_setsockopt+0x38/0x50
> net/core/sock.c:3130
>     [<0000000095eef4cf>] __sys_setsockopt+0x98/0x120 net/socket.c:2078
>     [<000000009747cf88>] __do_sys_setsockopt net/socket.c:2089 [inline]
>     [<000000009747cf88>] __se_sys_setsockopt net/socket.c:2086 [inline]
>     [<000000009747cf88>] __x64_sys_setsockopt+0x26/0x30 net/socket.c:2086
>     [<00000000ded8ba80>] do_syscall_64+0x76/0x1a0
> arch/x86/entry/common.c:301
>     [<00000000893b4ac8>] entry_SYSCALL_64_after_hwframe+0x44/0xa9
> 

The bug is that ownership of some memory is passed to a kthread started by
kthread_run(), but the kthread can be stopped before it actually executes the
threadfn.  See the code in kernel/kthread.c:

        ret = -EINTR;
        if (!test_bit(KTHREAD_SHOULD_STOP, &self->flags)) {
                cgroup_kthread_ready();
                __kthread_parkme(self);
                ret = threadfn(data);
        }

So, apparently the thread parameters must always be owned by the owner of the
kthread, not by the kthread itself.  It seems like this would be a common
mistake in kernel code; I'm surprised this doesn't come up more...

- Eric

^ permalink raw reply	[flat|nested] 3+ messages in thread
* Re: memory leak in start_sync_thread
  2019-06-11  1:06 ` Eric Biggers
@ 2019-06-11 19:52   ` Julian Anastasov
  0 siblings, 0 replies; 3+ messages in thread
From: Julian Anastasov @ 2019-06-11 19:52 UTC (permalink / raw)
  To: Eric Biggers
  Cc: syzbot, coreteam, davem, fw, horms, kadlec, linux-kernel,
	lvs-devel, netdev, netfilter-devel, pablo, syzkaller-bugs,
	wensong


	Hello,

On Mon, 10 Jun 2019, Eric Biggers wrote:

> On Tue, May 28, 2019 at 11:28:05AM -0700, syzbot wrote:
> > Hello,
> > 
> > syzbot found the following crash on:
> > 
> > HEAD commit:    cd6c84d8 Linux 5.2-rc2
> > git tree:       upstream
> > console output: https://syzkaller.appspot.com/x/log.txt?x=132bd44aa00000
> > kernel config:  https://syzkaller.appspot.com/x/.config?x=64479170dcaf0e11
> > dashboard link: https://syzkaller.appspot.com/bug?extid=7e2e50c8adfccd2e5041
> > compiler:       gcc (GCC) 9.0.0 20181231 (experimental)
> > syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=114b1354a00000
> > C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=14b7ad26a00000
> > 
> > IMPORTANT: if you fix the bug, please add the following tag to the commit:
> > Reported-by: syzbot+7e2e50c8adfccd2e5041@syzkaller.appspotmail.com
> > 
> > d started: state = MASTER, mcast_ifn = syz_tun, syncid = 0, id = 0
> > BUG: memory leak
> > unreferenced object 0xffff8881206bf700 (size 32):
> >   comm "syz-executor761", pid 7268, jiffies 4294943441 (age 20.470s)
> >   hex dump (first 32 bytes):
> >     00 40 7c 09 81 88 ff ff 80 45 b8 21 81 88 ff ff  .@|......E.!....
> >     00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
> >   backtrace:
> >     [<0000000057619e23>] kmemleak_alloc_recursive
> > include/linux/kmemleak.h:55 [inline]
> >     [<0000000057619e23>] slab_post_alloc_hook mm/slab.h:439 [inline]
> >     [<0000000057619e23>] slab_alloc mm/slab.c:3326 [inline]
> >     [<0000000057619e23>] kmem_cache_alloc_trace+0x13d/0x280 mm/slab.c:3553
> >     [<0000000086ce5479>] kmalloc include/linux/slab.h:547 [inline]
> >     [<0000000086ce5479>] start_sync_thread+0x5d2/0xe10
> > net/netfilter/ipvs/ip_vs_sync.c:1862
> >     [<000000001a9229cc>] do_ip_vs_set_ctl+0x4c5/0x780
> > net/netfilter/ipvs/ip_vs_ctl.c:2402
> >     [<00000000ece457c8>] nf_sockopt net/netfilter/nf_sockopt.c:106 [inline]
> >     [<00000000ece457c8>] nf_setsockopt+0x4c/0x80
> > net/netfilter/nf_sockopt.c:115
> >     [<00000000942f62d4>] ip_setsockopt net/ipv4/ip_sockglue.c:1258 [inline]
> >     [<00000000942f62d4>] ip_setsockopt+0x9b/0xb0 net/ipv4/ip_sockglue.c:1238
> >     [<00000000a56a8ffd>] udp_setsockopt+0x4e/0x90 net/ipv4/udp.c:2616
> >     [<00000000fa895401>] sock_common_setsockopt+0x38/0x50
> > net/core/sock.c:3130
> >     [<0000000095eef4cf>] __sys_setsockopt+0x98/0x120 net/socket.c:2078
> >     [<000000009747cf88>] __do_sys_setsockopt net/socket.c:2089 [inline]
> >     [<000000009747cf88>] __se_sys_setsockopt net/socket.c:2086 [inline]
> >     [<000000009747cf88>] __x64_sys_setsockopt+0x26/0x30 net/socket.c:2086
> >     [<00000000ded8ba80>] do_syscall_64+0x76/0x1a0
> > arch/x86/entry/common.c:301
> >     [<00000000893b4ac8>] entry_SYSCALL_64_after_hwframe+0x44/0xa9
> > 
> 
> The bug is that ownership of some memory is passed to a kthread started by
> kthread_run(), but the kthread can be stopped before it actually executes the
> threadfn.  See the code in kernel/kthread.c:
> 
>         ret = -EINTR;
>         if (!test_bit(KTHREAD_SHOULD_STOP, &self->flags)) {
>                 cgroup_kthread_ready();
>                 __kthread_parkme(self);
>                 ret = threadfn(data);
>         }
> 
> So, apparently the thread parameters must always be owned by the owner of the
> kthread, not by the kthread itself.  It seems like this would be a common
> mistake in kernel code; I'm surprised this doesn't come up more...

	Thanks! It explains the problem. It was not obvious from the
fact that only tinfo was reported as a leak, nothing for tinfo->sock.

	Moving sock_release to owner complicates the locking but
I'll try to fix it in the following days...

Regards

--
Julian Anastasov <ja@ssi.bg>

^ permalink raw reply	[flat|nested] 3+ messages in thread
end of thread, other threads:[~2019-06-11 19:53 UTC | newest]

Thread overview: 3+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2019-05-28 18:28 memory leak in start_sync_thread syzbot
2019-06-11  1:06 ` Eric Biggers
2019-06-11 19:52   ` Julian Anastasov

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