linux-cve-announce - CVE-2022-50342: floppy: Fix memory leak in do_floppy

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Message-ID: <2025091639-CVE-2022-50342-d7ef@gregkh>
Date: Tue, 16 Sep 2025 18:11:38 +0200
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...nel.org>
Subject: CVE-2022-50342: floppy: Fix memory leak in do_floppy_init()

From: Greg Kroah-Hartman <gregkh@...nel.org>

Description
===========

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]

The Linux kernel CVE team has assigned CVE-2022-50342 to this issue.


Affected and fixed versions
===========================

	Issue introduced in 5.11 with commit 302cfee150291c6cd85b1ca197d062d0b423d09c and fixed in 5.15.86 with commit f36d8c8651506aea5f09899f5356ece5d1384f50
	Issue introduced in 5.11 with commit 302cfee150291c6cd85b1ca197d062d0b423d09c and fixed in 6.0.16 with commit 75d8c8851a4da0190c2480e84315b5fd3d0356c5
	Issue introduced in 5.11 with commit 302cfee150291c6cd85b1ca197d062d0b423d09c and fixed in 6.1.2 with commit 55b3c66a0d441cd37154ae95e44d0b82ccfd580e
	Issue introduced in 5.11 with commit 302cfee150291c6cd85b1ca197d062d0b423d09c and fixed in 6.2 with commit f8ace2e304c5dd8a7328db9cd2b8a4b1b98d83ec

Please see https://www.kernel.org for a full list of currently supported
kernel versions by the kernel community.

Unaffected versions might change over time as fixes are backported to
older supported kernel versions.  The official CVE entry at
	https://cve.org/CVERecord/?id=CVE-2022-50342
will be updated if fixes are backported, please check that for the most
up to date information about this issue.


Affected files
==============

The file(s) affected by this issue are:
	drivers/block/floppy.c


Mitigation
==========

The Linux kernel CVE team recommends that you update to the latest
stable kernel version for this, and many other bugfixes.  Individual
changes are never tested alone, but rather are part of a larger kernel
release.  Cherry-picking individual commits is not recommended or
supported by the Linux kernel community at all.  If however, updating to
the latest release is impossible, the individual changes to resolve this
issue can be found at these commits:
	https://git.kernel.org/stable/c/f36d8c8651506aea5f09899f5356ece5d1384f50
	https://git.kernel.org/stable/c/75d8c8851a4da0190c2480e84315b5fd3d0356c5
	https://git.kernel.org/stable/c/55b3c66a0d441cd37154ae95e44d0b82ccfd580e
	https://git.kernel.org/stable/c/f8ace2e304c5dd8a7328db9cd2b8a4b1b98d83ec