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CVE-2021-47237

net: hamradio: fix memory leak in mkiss_close

Medium5.5EPSS 0.23%
Published
Updated
Reserved
Assigned by
Linux

Description

In the Linux kernel, the following vulnerability has been resolved: net: hamradio: fix memory leak in mkiss_close My local syzbot instance hit memory leak in mkiss_open()[1]. The problem was in missing free_netdev() in mkiss_close(). In mkiss_open() netdevice is allocated and then registered, but in mkiss_close() netdevice was only unregistered, but not freed. Fail log: BUG: memory leak unreferenced object 0xffff8880281ba000 (size 4096): comm "syz-executor.1", pid 11443, jiffies 4295046091 (age 17.660s) hex dump (first 32 bytes): 61 78 30 00 00 00 00 00 00 00 00 00 00 00 00 00 ax0............. 00 27 fa 2a 80 88 ff ff 00 00 00 00 00 00 00 00 .'.*............ backtrace: [<ffffffff81a27201>] kvmalloc_node+0x61/0xf0 [<ffffffff8706e7e8>] alloc_netdev_mqs+0x98/0xe80 [<ffffffff84e64192>] mkiss_open+0xb2/0x6f0 [1] [<ffffffff842355db>] tty_ldisc_open+0x9b/0x110 [<ffffffff84236488>] tty_set_ldisc+0x2e8/0x670 [<ffffffff8421f7f3>] tty_ioctl+0xda3/0x1440 [<ffffffff81c9f273>] __x64_sys_ioctl+0x193/0x200 [<ffffffff8911263a>] do_syscall_64+0x3a/0xb0 [<ffffffff89200068>] entry_SYSCALL_64_after_hwframe+0x44/0xae BUG: memory leak unreferenced object 0xffff8880141a9a00 (size 96): comm "syz-executor.1", pid 11443, jiffies 4295046091 (age 17.660s) hex dump (first 32 bytes): e8 a2 1b 28 80 88 ff ff e8 a2 1b 28 80 88 ff ff ...(.......(.... 98 92 9c aa b0 40 02 00 00 00 00 00 00 00 00 00 .....@.......... backtrace: [<ffffffff8709f68b>] __hw_addr_create_ex+0x5b/0x310 [<ffffffff8709fb38>] __hw_addr_add_ex+0x1f8/0x2b0 [<ffffffff870a0c7b>] dev_addr_init+0x10b/0x1f0 [<ffffffff8706e88b>] alloc_netdev_mqs+0x13b/0xe80 [<ffffffff84e64192>] mkiss_open+0xb2/0x6f0 [1] [<ffffffff842355db>] tty_ldisc_open+0x9b/0x110 [<ffffffff84236488>] tty_set_ldisc+0x2e8/0x670 [<ffffffff8421f7f3>] tty_ioctl+0xda3/0x1440 [<ffffffff81c9f273>] __x64_sys_ioctl+0x193/0x200 [<ffffffff8911263a>] do_syscall_64+0x3a/0xb0 [<ffffffff89200068>] entry_SYSCALL_64_after_hwframe+0x44/0xae BUG: memory leak unreferenced object 0xffff8880219bfc00 (size 512): comm "syz-executor.1", pid 11443, jiffies 4295046091 (age 17.660s) hex dump (first 32 bytes): 00 a0 1b 28 80 88 ff ff 80 8f b1 8d ff ff ff ff ...(............ 80 8f b1 8d ff ff ff ff 00 00 00 00 00 00 00 00 ................ backtrace: [<ffffffff81a27201>] kvmalloc_node+0x61/0xf0 [<ffffffff8706eec7>] alloc_netdev_mqs+0x777/0xe80 [<ffffffff84e64192>] mkiss_open+0xb2/0x6f0 [1] [<ffffffff842355db>] tty_ldisc_open+0x9b/0x110 [<ffffffff84236488>] tty_set_ldisc+0x2e8/0x670 [<ffffffff8421f7f3>] tty_ioctl+0xda3/0x1440 [<ffffffff81c9f273>] __x64_sys_ioctl+0x193/0x200 [<ffffffff8911263a>] do_syscall_64+0x3a/0xb0 [<ffffffff89200068>] entry_SYSCALL_64_after_hwframe+0x44/0xae BUG: memory leak unreferenced object 0xffff888029b2b200 (size 256): comm "syz-executor.1", pid 11443, jiffies 4295046091 (age 17.660s) 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: [<ffffffff81a27201>] kvmalloc_node+0x61/0xf0 [<ffffffff8706f062>] alloc_netdev_mqs+0x912/0xe80 [<ffffffff84e64192>] mkiss_open+0xb2/0x6f0 [1] [<ffffffff842355db>] tty_ldisc_open+0x9b/0x110 [<ffffffff84236488>] tty_set_ldisc+0x2e8/0x670 [<ffffffff8421f7f3>] tty_ioctl+0xda3/0x1440 [<ffffffff81c9f273>] __x64_sys_ioctl+0x193/0x200 [<ffffffff8911263a>] do_syscall_64+0x3a/0xb0 [<ffffffff89200068>] entry_SYSCALL_64_after_hwframe+0x44/0xae

Timeline

  1. ID reserved

    By Linux

  2. · 41 days later

    Published

  3. · 24 months later

    Record updated

Changes after publication (a new score, a public exploit, EPSS crossing 1, 10 or 50 %, leaving KEV) are kept since November 2026; earlier ones are not known.

Scores

CVSS scores of CVE-2021-47237, by who scored it
Scored byCVSSScoreVector
NVDNVD · Analyzed3.1Medium5.5CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
EPSS (exploitation in 30 days)
0.23% · top 87% of all CVEs (7 Nov 2026)
CISA SSVC
Exploitation: none · Automatable: no · Technical impact: partial
Loading the EPSS history…

The list uses the assigner's score when there is one, then CISA's, then NVD's: Medium 5.5.

Weakness

Affected products

  • Linux · Linux

    • affected 815f62bf742718458ba822a7e1f51f285eb997f2 – < c634ba0b4159838ff45a60d3a0ace3b4118077a5
    • affected 815f62bf742718458ba822a7e1f51f285eb997f2 – < 3942d0f9ace1a95a74930b5b4fc0e5005c62b37b
    • affected 815f62bf742718458ba822a7e1f51f285eb997f2 – < 765a8a04f828db7222b36a42b1031f576bfe95c3
    • affected 815f62bf742718458ba822a7e1f51f285eb997f2 – < c16c4716a1b5ba4f83c7e00da457cba06761f119
    • affected 815f62bf742718458ba822a7e1f51f285eb997f2 – < a49cbb762ef20655f5c91abdc13658b0af5e159d
    • affected 815f62bf742718458ba822a7e1f51f285eb997f2 – < 290b0b6432e2599021db0b8d6046f756d931c29f
    • affected 815f62bf742718458ba822a7e1f51f285eb997f2 – < f4de2b43d13b7cf3ced9310e371b90c836dbd7cd
    • affected 815f62bf742718458ba822a7e1f51f285eb997f2 – < 7edcc682301492380fbdd604b4516af5ae667a13

  • Linux · Linux

    • affected 2.6.14
    • unaffected < 2.6.14
    • unaffected 4.4.274 – ≤ 4.4.*
    • unaffected 4.9.274 – ≤ 4.9.*
    • unaffected 4.14.238 – ≤ 4.14.*
    • unaffected 4.19.196 – ≤ 4.19.*
    • unaffected 5.4.128 – ≤ 5.4.*
    • unaffected 5.10.46 – ≤ 5.10.*
    • unaffected 5.12.13 – ≤ 5.12.*
    • unaffected 5.13 – ≤ *

References (8)

Sources

The same CVE in the primary databases and aggregators, to check against.

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Record last updated .