md: fix kmemleak of rdev->serial

Vulnerability Description

In the Linux kernel, the following vulnerability has been resolved: md: fix kmemleak of rdev->serial If kobject_add() is fail in bind_rdev_to_array(), 'rdev->serial' will be alloc not be freed, and kmemleak occurs. unreferenced object 0xffff88815a350000 (size 49152): comm "mdadm", pid 789, jiffies 4294716910 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 (crc f773277a): [<0000000058b0a453>] kmemleak_alloc+0x61/0xe0 [<00000000366adf14>] __kmalloc_large_node+0x15e/0x270 [<000000002e82961b>] __kmalloc_node.cold+0x11/0x7f [<00000000f206d60a>] kvmalloc_node+0x74/0x150 [<0000000034bf3363>] rdev_init_serial+0x67/0x170 [<0000000010e08fe9>] mddev_create_serial_pool+0x62/0x220 [<00000000c3837bf0>] bind_rdev_to_array+0x2af/0x630 [<0000000073c28560>] md_add_new_disk+0x400/0x9f0 [<00000000770e30ff>] md_ioctl+0x15bf/0x1c10 [<000000006cfab718>] blkdev_ioctl+0x191/0x3f0 [<0000000085086a11>] vfs_ioctl+0x22/0x60 [<0000000018b656fe>] __x64_sys_ioctl+0xba/0xe0 [<00000000e54e675e>] do_syscall_64+0x71/0x150 [<000000008b0ad622>] entry_SYSCALL_64_after_hwframe+0x6c/0x74

References

• https://git.kernel.org/stable/c/fb5b347efd1bda989846ffc74679d181222fb123
• https://git.kernel.org/stable/c/f3a1787dc48213f6caea5ba7d47e0222e7fa34a9
• https://git.kernel.org/stable/c/beaf11969fd5cbe6f09cefaa34df1ce8578e8dd9
• https://git.kernel.org/stable/c/9fd0198f7ef06ae0d6636fb0578560857dead995
• https://git.kernel.org/stable/c/6d32c832a88513f65c2c2c9c75954ee8b387adea
• https://git.kernel.org/stable/c/4c1021ce46fc2fb6115f7e79d353941e6dcad366
• https://git.kernel.org/stable/c/6cf350658736681b9d6b0b6e58c5c76b235bb4c4