CVE-2022-50752
Unknown Unknown - Not Provided
Double Free Vulnerability in Linux Kernel md/raid5 Component

Publication date: 2025-12-24

Last updated on: 2025-12-24

Assigner: kernel.org

Description
In the Linux kernel, the following vulnerability has been resolved: md/raid5: Remove unnecessary bio_put() in raid5_read_one_chunk() When running chunk-sized reads on disks with badblocks duplicate bio free/puts are observed: ============================================================================= BUG bio-200 (Not tainted): Object already free ----------------------------------------------------------------------------- Allocated in mempool_alloc_slab+0x17/0x20 age=3 cpu=2 pid=7504 __slab_alloc.constprop.0+0x5a/0xb0 kmem_cache_alloc+0x31e/0x330 mempool_alloc_slab+0x17/0x20 mempool_alloc+0x100/0x2b0 bio_alloc_bioset+0x181/0x460 do_mpage_readpage+0x776/0xd00 mpage_readahead+0x166/0x320 blkdev_readahead+0x15/0x20 read_pages+0x13f/0x5f0 page_cache_ra_unbounded+0x18d/0x220 force_page_cache_ra+0x181/0x1c0 page_cache_sync_ra+0x65/0xb0 filemap_get_pages+0x1df/0xaf0 filemap_read+0x1e1/0x700 blkdev_read_iter+0x1e5/0x330 vfs_read+0x42a/0x570 Freed in mempool_free_slab+0x17/0x20 age=3 cpu=2 pid=7504 kmem_cache_free+0x46d/0x490 mempool_free_slab+0x17/0x20 mempool_free+0x66/0x190 bio_free+0x78/0x90 bio_put+0x100/0x1a0 raid5_make_request+0x2259/0x2450 md_handle_request+0x402/0x600 md_submit_bio+0xd9/0x120 __submit_bio+0x11f/0x1b0 submit_bio_noacct_nocheck+0x204/0x480 submit_bio_noacct+0x32e/0xc70 submit_bio+0x98/0x1a0 mpage_readahead+0x250/0x320 blkdev_readahead+0x15/0x20 read_pages+0x13f/0x5f0 page_cache_ra_unbounded+0x18d/0x220 Slab 0xffffea000481b600 objects=21 used=0 fp=0xffff8881206d8940 flags=0x17ffffc0010201(locked|slab|head|node=0|zone=2|lastcpupid=0x1fffff) CPU: 0 PID: 34525 Comm: kworker/u24:2 Not tainted 6.0.0-rc2-localyes-265166-gf11c5343fa3f #143 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.13.0-1ubuntu1.1 04/01/2014 Workqueue: raid5wq raid5_do_work Call Trace: <TASK> dump_stack_lvl+0x5a/0x78 dump_stack+0x10/0x16 print_trailer+0x158/0x165 object_err+0x35/0x50 free_debug_processing.cold+0xb7/0xbe __slab_free+0x1ae/0x330 kmem_cache_free+0x46d/0x490 mempool_free_slab+0x17/0x20 mempool_free+0x66/0x190 bio_free+0x78/0x90 bio_put+0x100/0x1a0 mpage_end_io+0x36/0x150 bio_endio+0x2fd/0x360 md_end_io_acct+0x7e/0x90 bio_endio+0x2fd/0x360 handle_failed_stripe+0x960/0xb80 handle_stripe+0x1348/0x3760 handle_active_stripes.constprop.0+0x72a/0xaf0 raid5_do_work+0x177/0x330 process_one_work+0x616/0xb20 worker_thread+0x2bd/0x6f0 kthread+0x179/0x1b0 ret_from_fork+0x22/0x30 </TASK> The double free is caused by an unnecessary bio_put() in the if(is_badblock(...)) error path in raid5_read_one_chunk(). The error path was moved ahead of bio_alloc_clone() in c82aa1b76787c ("md/raid5: move checking badblock before clone bio in raid5_read_one_chunk"). The previous code checked and freed align_bio which required a bio_put. After the move that is no longer needed as raid_bio is returned to the control of the common io path which performs its own endio resulting in a double free on bad device blocks.
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Meta Information
Published
2025-12-24
Last Modified
2025-12-24
Generated
2026-05-07
AI Q&A
2025-12-24
EPSS Evaluated
2026-05-05
NVD
CVE-2022-50752
EUVD
EUVD-2022-55809
Affected Vendors & Products
Showing 1 associated CPE
Vendor Product Version / Range
linux linux_kernel *
Helpful Resources
Exploitability
CWE
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KEV
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CWE ID Description
CWE-UNKNOWN
Attack-Flow Graph
AI Powered Q&A
Can you explain this vulnerability to me?

This vulnerability is a double free bug in the Linux kernel's md/raid5 subsystem. It occurs because of an unnecessary bio_put() call in the raid5_read_one_chunk() function when handling chunk-sized reads on disks with bad blocks. The error path was changed so that the bio_put() call became redundant, leading to the same bio object being freed twice. This can cause kernel memory corruption or crashes.


How can this vulnerability impact me? :

The double free vulnerability can lead to kernel memory corruption, which may cause system instability, crashes, or potential denial of service. In some cases, it could be exploited to execute arbitrary code with kernel privileges, compromising system security.


How can this vulnerability be detected on my network or system? Can you suggest some commands?

This vulnerability can be detected by observing kernel logs for duplicate bio free/put errors, specifically messages like 'BUG bio-200 (Not tainted): Object already free' related to raid5_read_one_chunk operations. Monitoring dmesg or kernel logs for such error traces can help identify the issue. For example, you can use the command 'dmesg | grep -i "bio_put"' or 'journalctl -k | grep -i "bio_put"' to look for relevant error messages.


What immediate steps should I take to mitigate this vulnerability?

Immediate mitigation involves updating the Linux kernel to a version where the unnecessary bio_put() call in raid5_read_one_chunk() has been removed, as this fixes the double free issue. Until the patch is applied, avoid running chunk-sized reads on disks with bad blocks in RAID5 configurations to reduce the chance of triggering the bug.


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