fkie_cve-2023-53685
Vulnerability from fkie_nvd
Published
2025-10-07 16:15
Modified
2025-10-08 19:38
Severity ?
Summary
In the Linux kernel, the following vulnerability has been resolved: tun: Fix memory leak for detached NAPI queue. syzkaller reported [0] memory leaks of sk and skb related to the TUN device with no repro, but we can reproduce it easily with: struct ifreq ifr = {} int fd_tun, fd_tmp; char buf[4] = {}; fd_tun = openat(AT_FDCWD, "/dev/net/tun", O_WRONLY, 0); ifr.ifr_flags = IFF_TUN | IFF_NAPI | IFF_MULTI_QUEUE; ioctl(fd_tun, TUNSETIFF, &ifr); ifr.ifr_flags = IFF_DETACH_QUEUE; ioctl(fd_tun, TUNSETQUEUE, &ifr); fd_tmp = socket(AF_PACKET, SOCK_PACKET, 0); ifr.ifr_flags = IFF_UP; ioctl(fd_tmp, SIOCSIFFLAGS, &ifr); write(fd_tun, buf, sizeof(buf)); close(fd_tun); If we enable NAPI and multi-queue on a TUN device, we can put skb into tfile->sk.sk_write_queue after the queue is detached. We should prevent it by checking tfile->detached before queuing skb. Note this must be done under tfile->sk.sk_write_queue.lock because write() and ioctl(IFF_DETACH_QUEUE) can run concurrently. Otherwise, there would be a small race window: write() ioctl(IFF_DETACH_QUEUE) `- tun_get_user `- __tun_detach |- if (tfile->detached) |- tun_disable_queue | `-> false | `- tfile->detached = tun | `- tun_queue_purge |- spin_lock_bh(&queue->lock) `- __skb_queue_tail(queue, skb) Another solution is to call tun_queue_purge() when closing and reattaching the detached queue, but it could paper over another problems. Also, we do the same kind of test for IFF_NAPI_FRAGS. [0]: unreferenced object 0xffff88801edbc800 (size 2048): comm "syz-executor.1", pid 33269, jiffies 4295743834 (age 18.756s) hex dump (first 32 bytes): 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 00 00 07 40 00 00 00 00 00 00 00 00 00 00 00 00 ...@............ backtrace: [<000000008c16ea3d>] __do_kmalloc_node mm/slab_common.c:965 [inline] [<000000008c16ea3d>] __kmalloc+0x4a/0x130 mm/slab_common.c:979 [<000000003addde56>] kmalloc include/linux/slab.h:563 [inline] [<000000003addde56>] sk_prot_alloc+0xef/0x1b0 net/core/sock.c:2035 [<000000003e20621f>] sk_alloc+0x36/0x2f0 net/core/sock.c:2088 [<0000000028e43843>] tun_chr_open+0x3d/0x190 drivers/net/tun.c:3438 [<000000001b0f1f28>] misc_open+0x1a6/0x1f0 drivers/char/misc.c:165 [<000000004376f706>] chrdev_open+0x111/0x300 fs/char_dev.c:414 [<00000000614d379f>] do_dentry_open+0x2f9/0x750 fs/open.c:920 [<000000008eb24774>] do_open fs/namei.c:3636 [inline] [<000000008eb24774>] path_openat+0x143f/0x1a30 fs/namei.c:3791 [<00000000955077b5>] do_filp_open+0xce/0x1c0 fs/namei.c:3818 [<00000000b78973b0>] do_sys_openat2+0xf0/0x260 fs/open.c:1356 [<00000000057be699>] do_sys_open fs/open.c:1372 [inline] [<00000000057be699>] __do_sys_openat fs/open.c:1388 [inline] [<00000000057be699>] __se_sys_openat fs/open.c:1383 [inline] [<00000000057be699>] __x64_sys_openat+0x83/0xf0 fs/open.c:1383 [<00000000a7d2182d>] do_syscall_x64 arch/x86/entry/common.c:50 [inline] [<00000000a7d2182d>] do_syscall_64+0x3c/0x90 arch/x86/entry/common.c:80 [<000000004cc4e8c4>] entry_SYSCALL_64_after_hwframe+0x72/0xdc unreferenced object 0xffff88802f671700 (size 240): comm "syz-executor.1", pid 33269, jiffies 4295743854 (age 18.736s) hex dump (first 32 bytes): 68 c9 db 1e 80 88 ff ff 68 c9 db 1e 80 88 ff ff h.......h....... 00 c0 7b 2f 80 88 ff ff 00 c8 db 1e 80 88 ff ff ..{/............ backtrace: [<00000000e9d9fdb6>] __alloc_skb+0x223/0x250 net/core/skbuff.c:644 [<000000002c3e4e0b>] alloc_skb include/linux/skbuff.h:1288 [inline] [<000000002c3e4e0b>] alloc_skb_with_frags+0x6f/0x350 net/core/skbuff.c:6378 [<00000000825f98d7>] sock_alloc_send_pskb+0x3ac/0x3e0 net/core/sock.c:2729 [<00000000e9eb3df3>] tun_alloc_skb drivers/net/tun.c:1529 [inline] [< ---truncated---
References
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/0d20210a190f76db9ec35ee4e0fc77e6c7a148f5
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/82b2bc279467c875ec36f8ef820f00997c2a4e8e
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/9cae243b9ae25adfe468cd47ceca591f6725b79c
Impacted products
Vendor Product Version


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{
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\ntun: Fix memory leak for detached NAPI queue.\n\nsyzkaller reported [0] memory leaks of sk and skb related to the TUN\ndevice with no repro, but we can reproduce it easily with:\n\n  struct ifreq ifr = {}\n  int fd_tun, fd_tmp;\n  char buf[4] = {};\n\n  fd_tun = openat(AT_FDCWD, \"/dev/net/tun\", O_WRONLY, 0);\n  ifr.ifr_flags = IFF_TUN | IFF_NAPI | IFF_MULTI_QUEUE;\n  ioctl(fd_tun, TUNSETIFF, \u0026ifr);\n\n  ifr.ifr_flags = IFF_DETACH_QUEUE;\n  ioctl(fd_tun, TUNSETQUEUE, \u0026ifr);\n\n  fd_tmp = socket(AF_PACKET, SOCK_PACKET, 0);\n  ifr.ifr_flags = IFF_UP;\n  ioctl(fd_tmp, SIOCSIFFLAGS, \u0026ifr);\n\n  write(fd_tun, buf, sizeof(buf));\n  close(fd_tun);\n\nIf we enable NAPI and multi-queue on a TUN device, we can put skb into\ntfile-\u003esk.sk_write_queue after the queue is detached.  We should prevent\nit by checking tfile-\u003edetached before queuing skb.\n\nNote this must be done under tfile-\u003esk.sk_write_queue.lock because write()\nand ioctl(IFF_DETACH_QUEUE) can run concurrently.  Otherwise, there would\nbe a small race window:\n\n  write()                             ioctl(IFF_DETACH_QUEUE)\n  `- tun_get_user                     `- __tun_detach\n     |- if (tfile-\u003edetached)             |- tun_disable_queue\n     |  `-\u003e false                        |  `- tfile-\u003edetached = tun\n     |                                   `- tun_queue_purge\n     |- spin_lock_bh(\u0026queue-\u003elock)\n     `- __skb_queue_tail(queue, skb)\n\nAnother solution is to call tun_queue_purge() when closing and\nreattaching the detached queue, but it could paper over another\nproblems.  Also, we do the same kind of test for IFF_NAPI_FRAGS.\n\n[0]:\nunreferenced object 0xffff88801edbc800 (size 2048):\n  comm \"syz-executor.1\", pid 33269, jiffies 4295743834 (age 18.756s)\n  hex dump (first 32 bytes):\n    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................\n    00 00 07 40 00 00 00 00 00 00 00 00 00 00 00 00  ...@............\n  backtrace:\n    [\u003c000000008c16ea3d\u003e] __do_kmalloc_node mm/slab_common.c:965 [inline]\n    [\u003c000000008c16ea3d\u003e] __kmalloc+0x4a/0x130 mm/slab_common.c:979\n    [\u003c000000003addde56\u003e] kmalloc include/linux/slab.h:563 [inline]\n    [\u003c000000003addde56\u003e] sk_prot_alloc+0xef/0x1b0 net/core/sock.c:2035\n    [\u003c000000003e20621f\u003e] sk_alloc+0x36/0x2f0 net/core/sock.c:2088\n    [\u003c0000000028e43843\u003e] tun_chr_open+0x3d/0x190 drivers/net/tun.c:3438\n    [\u003c000000001b0f1f28\u003e] misc_open+0x1a6/0x1f0 drivers/char/misc.c:165\n    [\u003c000000004376f706\u003e] chrdev_open+0x111/0x300 fs/char_dev.c:414\n    [\u003c00000000614d379f\u003e] do_dentry_open+0x2f9/0x750 fs/open.c:920\n    [\u003c000000008eb24774\u003e] do_open fs/namei.c:3636 [inline]\n    [\u003c000000008eb24774\u003e] path_openat+0x143f/0x1a30 fs/namei.c:3791\n    [\u003c00000000955077b5\u003e] do_filp_open+0xce/0x1c0 fs/namei.c:3818\n    [\u003c00000000b78973b0\u003e] do_sys_openat2+0xf0/0x260 fs/open.c:1356\n    [\u003c00000000057be699\u003e] do_sys_open fs/open.c:1372 [inline]\n    [\u003c00000000057be699\u003e] __do_sys_openat fs/open.c:1388 [inline]\n    [\u003c00000000057be699\u003e] __se_sys_openat fs/open.c:1383 [inline]\n    [\u003c00000000057be699\u003e] __x64_sys_openat+0x83/0xf0 fs/open.c:1383\n    [\u003c00000000a7d2182d\u003e] do_syscall_x64 arch/x86/entry/common.c:50 [inline]\n    [\u003c00000000a7d2182d\u003e] do_syscall_64+0x3c/0x90 arch/x86/entry/common.c:80\n    [\u003c000000004cc4e8c4\u003e] entry_SYSCALL_64_after_hwframe+0x72/0xdc\n\nunreferenced object 0xffff88802f671700 (size 240):\n  comm \"syz-executor.1\", pid 33269, jiffies 4295743854 (age 18.736s)\n  hex dump (first 32 bytes):\n    68 c9 db 1e 80 88 ff ff 68 c9 db 1e 80 88 ff ff  h.......h.......\n    00 c0 7b 2f 80 88 ff ff 00 c8 db 1e 80 88 ff ff  ..{/............\n  backtrace:\n    [\u003c00000000e9d9fdb6\u003e] __alloc_skb+0x223/0x250 net/core/skbuff.c:644\n    [\u003c000000002c3e4e0b\u003e] alloc_skb include/linux/skbuff.h:1288 [inline]\n    [\u003c000000002c3e4e0b\u003e] alloc_skb_with_frags+0x6f/0x350 net/core/skbuff.c:6378\n    [\u003c00000000825f98d7\u003e] sock_alloc_send_pskb+0x3ac/0x3e0 net/core/sock.c:2729\n    [\u003c00000000e9eb3df3\u003e] tun_alloc_skb drivers/net/tun.c:1529 [inline]\n    [\u003c\n---truncated---"
    }
  ],
  "id": "CVE-2023-53685",
  "lastModified": "2025-10-08T19:38:09.863",
  "metrics": {},
  "published": "2025-10-07T16:15:52.777",
  "references": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/0d20210a190f76db9ec35ee4e0fc77e6c7a148f5"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/82b2bc279467c875ec36f8ef820f00997c2a4e8e"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/9cae243b9ae25adfe468cd47ceca591f6725b79c"
    }
  ],
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Awaiting Analysis"
}


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