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: [] kvmalloc_node+0x61/0xf0 [] alloc_netdev_mqs+0x98/0xe80 [] mkiss_open+0xb2/0x6f0 [1] [] tty_ldisc_open+0x9b/0x110 [] tty_set_ldisc+0x2e8/0x670 [] tty_ioctl+0xda3/0x1440 [] __x64_sys_ioctl+0x193/0x200 [] do_syscall_64+0x3a/0xb0 [] 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: [] __hw_addr_create_ex+0x5b/0x310 [] __hw_addr_add_ex+0x1f8/0x2b0 [] dev_addr_init+0x10b/0x1f0 [] alloc_netdev_mqs+0x13b/0xe80 [] mkiss_open+0xb2/0x6f0 [1] [] tty_ldisc_open+0x9b/0x110 [] tty_set_ldisc+0x2e8/0x670 [] tty_ioctl+0xda3/0x1440 [] __x64_sys_ioctl+0x193/0x200 [] do_syscall_64+0x3a/0xb0 [] 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: [] kvmalloc_node+0x61/0xf0 [] alloc_netdev_mqs+0x777/0xe80 [] mkiss_open+0xb2/0x6f0 [1] [] tty_ldisc_open+0x9b/0x110 [] tty_set_ldisc+0x2e8/0x670 [] tty_ioctl+0xda3/0x1440 [] __x64_sys_ioctl+0x193/0x200 [] do_syscall_64+0x3a/0xb0 [] 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: [] kvmalloc_node+0x61/0xf0 [] alloc_netdev_mqs+0x912/0xe80 [] mkiss_open+0xb2/0x6f0 [1] [] tty_ldisc_open+0x9b/0x110 [] tty_set_ldisc+0x2e8/0x670 [] tty_ioctl+0xda3/0x1440 [] __x64_sys_ioctl+0x193/0x200 [] do_syscall_64+0x3a/0xb0 [] entry_SYSCALL_64_after_hwframe+0x44/0xae

CVE-2021-47237 Blast Radius

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