Re: [syzbot] [net?] memory leak in tcp_md5_do_add

[Dmitry Safonov]

On 9/21/23 17:59, Eric Dumazet wrote:
> On Thu, Sep 21, 2023 at 6:56 PM syzbot
> <syzbot+68662811b3d5f6695bcb@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote:
>>
>> Hello,
>>
>> syzbot found the following issue on:
>>
>> HEAD commit:    ee3f96b16468 Merge tag 'nfsd-6.3-1' of git://git.kernel.or..
>> git tree:       upstream
>> console output: https://syzkaller.appspot.com/x/log.txt?x=1312bba8c80000
>> kernel config:  https://syzkaller.appspot.com/x/.config?x=f5733ca1757172ad
>> dashboard link: https://syzkaller.appspot.com/bug?extid=68662811b3d5f6695bcb
>> compiler:       gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2
>> syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=105393a8c80000
>> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=1113917f480000
>>
>> Downloadable assets:
>> disk image: https://storage.googleapis.com/syzbot-assets/29e7966ab711/disk-ee3f96b1.raw.xz
>> vmlinux: https://storage.googleapis.com/syzbot-assets/ae21b8e855de/vmlinux-ee3f96b1.xz
>> kernel image: https://storage.googleapis.com/syzbot-assets/803ee0425ad6/bzImage-ee3f96b1.xz
>>
>> IMPORTANT: if you fix the issue, please add the following tag to the commit:
>> Reported-by: syzbot+68662811b3d5f6695bcb@xxxxxxxxxxxxxxxxxxxxxxxxx
>>
>> executing program
>> BUG: memory leak
>> unreferenced object 0xffff88810a86f7a0 (size 32):
>>   comm "syz-executor325", pid 5099, jiffies 4294978342 (age 119.240s)
>>   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:
>>     [<ffffffff81533d64>] kmalloc_trace+0x24/0x90 mm/slab_common.c:1061
>>     [<ffffffff840edaa0>] kmalloc include/linux/slab.h:580 [inline]
>>     [<ffffffff840edaa0>] tcp_md5sig_info_add net/ipv4/tcp_ipv4.c:1169 [inline]
>>     [<ffffffff840edaa0>] tcp_md5_do_add+0xa0/0x150 net/ipv4/tcp_ipv4.c:1240
>>     [<ffffffff84262c73>] tcp_v6_parse_md5_keys+0x253/0x4a0 net/ipv6/tcp_ipv6.c:671
>>     [<ffffffff840c720e>] do_tcp_setsockopt+0x40e/0x1360 net/ipv4/tcp.c:3720
>>     [<ffffffff840c81fb>] tcp_setsockopt+0x9b/0xa0 net/ipv4/tcp.c:3806
>>     [<ffffffff83d72a8b>] __sys_setsockopt+0x1ab/0x330 net/socket.c:2274
>>     [<ffffffff83d72c36>] __do_sys_setsockopt net/socket.c:2285 [inline]
>>     [<ffffffff83d72c36>] __se_sys_setsockopt net/socket.c:2282 [inline]
>>     [<ffffffff83d72c36>] __x64_sys_setsockopt+0x26/0x30 net/socket.c:2282
>>     [<ffffffff849ad699>] do_syscall_x64 arch/x86/entry/common.c:50 [inline]
>>     [<ffffffff849ad699>] do_syscall_64+0x39/0xb0 arch/x86/entry/common.c:80
>>     [<ffffffff84a0008b>] entry_SYSCALL_64_after_hwframe+0x63/0xcd
>>
>> BUG: memory leak
>> unreferenced object 0xffff88811225ccc0 (size 192):
>>   comm "syz-executor325", pid 5099, jiffies 4294978342 (age 119.240s)
>>   hex dump (first 32 bytes):
>>     00 00 00 00 00 00 00 00 22 01 00 00 00 00 ad de  ........".......
>>     22 0a 80 00 fe 80 00 00 00 00 00 00 00 00 00 00  "...............
>>   backtrace:
>>     [<ffffffff8153444a>] __do_kmalloc_node mm/slab_common.c:966 [inline]
>>     [<ffffffff8153444a>] __kmalloc+0x4a/0x120 mm/slab_common.c:980
>>     [<ffffffff83d75c15>] kmalloc include/linux/slab.h:584 [inline]
>>     [<ffffffff83d75c15>] sock_kmalloc net/core/sock.c:2635 [inline]
>>     [<ffffffff83d75c15>] sock_kmalloc+0x65/0xa0 net/core/sock.c:2624
>>     [<ffffffff840eb9bb>] __tcp_md5_do_add+0xcb/0x300 net/ipv4/tcp_ipv4.c:1212
>>     [<ffffffff840eda67>] tcp_md5_do_add+0x67/0x150 net/ipv4/tcp_ipv4.c:1253
>>     [<ffffffff84262c73>] tcp_v6_parse_md5_keys+0x253/0x4a0 net/ipv6/tcp_ipv6.c:671
>>     [<ffffffff840c720e>] do_tcp_setsockopt+0x40e/0x1360 net/ipv4/tcp.c:3720
>>     [<ffffffff840c81fb>] tcp_setsockopt+0x9b/0xa0 net/ipv4/tcp.c:3806
>>     [<ffffffff83d72a8b>] __sys_setsockopt+0x1ab/0x330 net/socket.c:2274
>>     [<ffffffff83d72c36>] __do_sys_setsockopt net/socket.c:2285 [inline]
>>     [<ffffffff83d72c36>] __se_sys_setsockopt net/socket.c:2282 [inline]
>>     [<ffffffff83d72c36>] __x64_sys_setsockopt+0x26/0x30 net/socket.c:2282
>>     [<ffffffff849ad699>] do_syscall_x64 arch/x86/entry/common.c:50 [inline]
>>     [<ffffffff849ad699>] do_syscall_64+0x39/0xb0 arch/x86/entry/common.c:80
>>     [<ffffffff84a0008b>] entry_SYSCALL_64_after_hwframe+0x63/0xcd
>>
>>
>>
>> ---
>> This report is generated by a bot. It may contain errors.
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>>
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>>
>> If the bug is already fixed, let syzbot know by replying with:
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>>
>> If you want syzbot to run the reproducer, reply with:
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>>
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>> (See the list of subsystem names on the web dashboard)
>>
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>>
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>> #syz undup
> 
> Dmitry, please take a look at this bug, we need to fix it before your
> patch series.

Sure, seems reasonable to me to fix before merging something on top.

> Thank you.

Thanks,
           Dmitry