memory leak in kcm_sendmsg

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit:    f2850dd5 Merge tag 'kbuild-fixes-v5.6' of git://git.kernel..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=15b6e2a1e00000
kernel config:  https://syzkaller.appspot.com/x/.config?x=2802e33434f4f863
dashboard link: https://syzkaller.appspot.com/bug?extid=b039f5699bd82e1fb011
compiler:       gcc (GCC) 9.0.0 20181231 (experimental)
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=1036aae6e00000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=14a48aa1e00000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+b039f5699bd82e1fb011@xxxxxxxxxxxxxxxxxxxxxxxxx

executing program
executing program
BUG: memory leak
unreferenced object 0xffff88812166aa00 (size 224):
  comm "syz-executor252", pid 7098, jiffies 4294946073 (age 7.970s)
  hex dump (first 32 bytes):
    00 5f 7e 21 81 88 ff ff 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:
    [<00000000344c790c>] kmemleak_alloc_recursive include/linux/kmemleak.h:43 [inline]
    [<00000000344c790c>] slab_post_alloc_hook mm/slab.h:586 [inline]
    [<00000000344c790c>] slab_alloc_node mm/slab.c:3263 [inline]
    [<00000000344c790c>] kmem_cache_alloc_node+0x163/0x2f0 mm/slab.c:3575
    [<0000000055638a6a>] __alloc_skb+0x6e/0x210 net/core/skbuff.c:198
    [<00000000e5df7d05>] alloc_skb include/linux/skbuff.h:1051 [inline]
    [<00000000e5df7d05>] kcm_sendmsg+0x63e/0xa6b net/kcm/kcmsock.c:969
    [<000000001a13b16a>] sock_sendmsg_nosec net/socket.c:652 [inline]
    [<000000001a13b16a>] sock_sendmsg+0x54/0x70 net/socket.c:672
    [<0000000051101f49>] ____sys_sendmsg+0x123/0x300 net/socket.c:2343
    [<000000002286b08d>] ___sys_sendmsg+0x8a/0xd0 net/socket.c:2397
    [<0000000027623508>] __sys_sendmmsg+0xf4/0x270 net/socket.c:2487
    [<00000000a5d459c2>] __do_sys_sendmmsg net/socket.c:2516 [inline]
    [<00000000a5d459c2>] __se_sys_sendmmsg net/socket.c:2513 [inline]
    [<00000000a5d459c2>] __x64_sys_sendmmsg+0x28/0x30 net/socket.c:2513
    [<00000000345a6e04>] do_syscall_64+0x73/0x220 arch/x86/entry/common.c:294
    [<00000000e4a592cb>] entry_SYSCALL_64_after_hwframe+0x44/0xa9

BUG: memory leak
unreferenced object 0xffff888123b6fa00 (size 512):
  comm "syz-executor252", pid 7098, jiffies 4294946073 (age 7.970s)
  hex dump (first 32 bytes):
    00 00 33 33 00 00 00 02 42 01 0a 80 00 42 86 dd  ..33....B....B..
    60 00 00 00 00 10 3a ff fe 80 00 00 00 00 00 00  `.....:.........
  backtrace:
    [<000000003f7d57be>] kmemleak_alloc_recursive include/linux/kmemleak.h:43 [inline]
    [<000000003f7d57be>] slab_post_alloc_hook mm/slab.h:586 [inline]
    [<000000003f7d57be>] slab_alloc_node mm/slab.c:3263 [inline]
    [<000000003f7d57be>] kmem_cache_alloc_node_trace+0x161/0x2f0 mm/slab.c:3593
    [<000000007b27008a>] __do_kmalloc_node mm/slab.c:3615 [inline]
    [<000000007b27008a>] __kmalloc_node_track_caller+0x38/0x50 mm/slab.c:3630
    [<00000000b67c7fa9>] __kmalloc_reserve.isra.0+0x40/0xb0 net/core/skbuff.c:142
    [<0000000084d25a21>] __alloc_skb+0xa0/0x210 net/core/skbuff.c:210
    [<00000000e5df7d05>] alloc_skb include/linux/skbuff.h:1051 [inline]
    [<00000000e5df7d05>] kcm_sendmsg+0x63e/0xa6b net/kcm/kcmsock.c:969
    [<000000001a13b16a>] sock_sendmsg_nosec net/socket.c:652 [inline]
    [<000000001a13b16a>] sock_sendmsg+0x54/0x70 net/socket.c:672
    [<0000000051101f49>] ____sys_sendmsg+0x123/0x300 net/socket.c:2343
    [<000000002286b08d>] ___sys_sendmsg+0x8a/0xd0 net/socket.c:2397
    [<0000000027623508>] __sys_sendmmsg+0xf4/0x270 net/socket.c:2487
    [<00000000a5d459c2>] __do_sys_sendmmsg net/socket.c:2516 [inline]
    [<00000000a5d459c2>] __se_sys_sendmmsg net/socket.c:2513 [inline]
    [<00000000a5d459c2>] __x64_sys_sendmmsg+0x28/0x30 net/socket.c:2513
    [<00000000345a6e04>] do_syscall_64+0x73/0x220 arch/x86/entry/common.c:294
    [<00000000e4a592cb>] entry_SYSCALL_64_after_hwframe+0x44/0xa9

BUG: memory leak
unreferenced object 0xffff8881217e5f00 (size 224):
  comm "syz-executor252", pid 7098, jiffies 4294946073 (age 7.970s)
  hex dump (first 32 bytes):
    00 5e 7e 21 81 88 ff ff 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:
    [<00000000344c790c>] kmemleak_alloc_recursive include/linux/kmemleak.h:43 [inline]
    [<00000000344c790c>] slab_post_alloc_hook mm/slab.h:586 [inline]
    [<00000000344c790c>] slab_alloc_node mm/slab.c:3263 [inline]
    [<00000000344c790c>] kmem_cache_alloc_node+0x163/0x2f0 mm/slab.c:3575
    [<0000000055638a6a>] __alloc_skb+0x6e/0x210 net/core/skbuff.c:198
    [<00000000e5df7d05>] alloc_skb include/linux/skbuff.h:1051 [inline]
    [<00000000e5df7d05>] kcm_sendmsg+0x63e/0xa6b net/kcm/kcmsock.c:969
    [<000000001a13b16a>] sock_sendmsg_nosec net/socket.c:652 [inline]
    [<000000001a13b16a>] sock_sendmsg+0x54/0x70 net/socket.c:672
    [<0000000051101f49>] ____sys_sendmsg+0x123/0x300 net/socket.c:2343
    [<000000002286b08d>] ___sys_sendmsg+0x8a/0xd0 net/socket.c:2397
    [<0000000027623508>] __sys_sendmmsg+0xf4/0x270 net/socket.c:2487
    [<00000000a5d459c2>] __do_sys_sendmmsg net/socket.c:2516 [inline]
    [<00000000a5d459c2>] __se_sys_sendmmsg net/socket.c:2513 [inline]
    [<00000000a5d459c2>] __x64_sys_sendmmsg+0x28/0x30 net/socket.c:2513
    [<00000000345a6e04>] do_syscall_64+0x73/0x220 arch/x86/entry/common.c:294
    [<00000000e4a592cb>] entry_SYSCALL_64_after_hwframe+0x44/0xa9

BUG: memory leak
unreferenced object 0xffff88812084ae00 (size 512):
  comm "syz-executor252", pid 7098, jiffies 4294946073 (age 7.970s)
  hex dump (first 32 bytes):
    a3 0f 00 00 00 00 00 00 40 00 00 00 00 00 00 00  ........@.......
    40 00 40 00 00 00 00 00 40 00 40 00 00 00 00 00  @.@.....@.@.....
  backtrace:
    [<000000003f7d57be>] kmemleak_alloc_recursive include/linux/kmemleak.h:43 [inline]
    [<000000003f7d57be>] slab_post_alloc_hook mm/slab.h:586 [inline]
    [<000000003f7d57be>] slab_alloc_node mm/slab.c:3263 [inline]
    [<000000003f7d57be>] kmem_cache_alloc_node_trace+0x161/0x2f0 mm/slab.c:3593
    [<000000007b27008a>] __do_kmalloc_node mm/slab.c:3615 [inline]
    [<000000007b27008a>] __kmalloc_node_track_caller+0x38/0x50 mm/slab.c:3630
    [<00000000b67c7fa9>] __kmalloc_reserve.isra.0+0x40/0xb0 net/core/skbuff.c:142
    [<0000000084d25a21>] __alloc_skb+0xa0/0x210 net/core/skbuff.c:210
    [<00000000e5df7d05>] alloc_skb include/linux/skbuff.h:1051 [inline]
    [<00000000e5df7d05>] kcm_sendmsg+0x63e/0xa6b net/kcm/kcmsock.c:969
    [<000000001a13b16a>] sock_sendmsg_nosec net/socket.c:652 [inline]
    [<000000001a13b16a>] sock_sendmsg+0x54/0x70 net/socket.c:672
    [<0000000051101f49>] ____sys_sendmsg+0x123/0x300 net/socket.c:2343
    [<000000002286b08d>] ___sys_sendmsg+0x8a/0xd0 net/socket.c:2397
    [<0000000027623508>] __sys_sendmmsg+0xf4/0x270 net/socket.c:2487
    [<00000000a5d459c2>] __do_sys_sendmmsg net/socket.c:2516 [inline]
    [<00000000a5d459c2>] __se_sys_sendmmsg net/socket.c:2513 [inline]
    [<00000000a5d459c2>] __x64_sys_sendmmsg+0x28/0x30 net/socket.c:2513
    [<00000000345a6e04>] do_syscall_64+0x73/0x220 arch/x86/entry/common.c:294
    [<00000000e4a592cb>] entry_SYSCALL_64_after_hwframe+0x44/0xa9



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