floppy: Fix memory leak in do_floppy_init()

In the Linux kernel, the following vulnerability has been resolved:

floppy: Fix memory leak in do_floppy_init()

A memory leak was reported when floppy_alloc_disk() failed in

do_floppy_init().

unreferenced object 0xffff888115ed25a0 (size 8):

comm "modprobe", pid 727, jiffies 4295051278 (age 25.529s)

hex dump (first 8 bytes):

00 ac 67 5b 81 88 ff ff ..g[....

backtrace:

[<000000007f457abb>] __kmalloc_node+0x4c/0xc0

[<00000000a87bfa9e>] blk_mq_realloc_tag_set_tags.part.0+0x6f/0x180

[<000000006f02e8b1>] blk_mq_alloc_tag_set+0x573/0x1130

[<0000000066007fd7>] 0xffffffffc06b8b08

[<0000000081f5ac40>] do_one_initcall+0xd0/0x4f0

[<00000000e26d04ee>] do_init_module+0x1a4/0x680

[<000000001bb22407>] load_module+0x6249/0x7110

[<00000000ad31ac4d>] __do_sys_finit_module+0x140/0x200

[<000000007bddca46>] do_syscall_64+0x35/0x80

[<00000000b5afec39>] entry_SYSCALL_64_after_hwframe+0x46/0xb0

unreferenced object 0xffff88810fc30540 (size 32):

comm "modprobe", pid 727, jiffies 4295051278 (age 25.529s)

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:

[<000000007f457abb>] __kmalloc_node+0x4c/0xc0

[<000000006b91eab4>] blk_mq_alloc_tag_set+0x393/0x1130

[<0000000066007fd7>] 0xffffffffc06b8b08

[<0000000081f5ac40>] do_one_initcall+0xd0/0x4f0

[<00000000e26d04ee>] do_init_module+0x1a4/0x680

[<000000001bb22407>] load_module+0x6249/0x7110

[<00000000ad31ac4d>] __do_sys_finit_module+0x140/0x200

[<000000007bddca46>] do_syscall_64+0x35/0x80

[<00000000b5afec39>] entry_SYSCALL_64_after_hwframe+0x46/0xb0

If the floppy_alloc_disk() failed, disks of current drive will not be set,

thus the lastest allocated set->tag cannot be freed in the error handling

path. A simple call graph shown as below:

floppy_module_init()

floppy_init()

do_floppy_init()

for (drive = 0; drive < N_DRIVE; drive++)

blk_mq_alloc_tag_set()

blk_mq_alloc_tag_set_tags()

blk_mq_realloc_tag_set_tags() # set->tag allocated

floppy_alloc_disk()

blk_mq_alloc_disk() # error occurred, disks failed to allocated

->out_put_disk:

for (drive = 0; drive < N_DRIVE; drive++)

if (!disks[drive][0]) # the last disks is not set and loop break

break;

blk_mq_free_tag_set() # the latest allocated set->tag leaked

Fix this problem by free the set->tag of current drive before jump to

error handling path.

[efremov: added stable list, changed title]