medium CVSS 5.5

CVE-2023-52739·Kernel vulnerability

In the Linux kernel, the following vulnerability has been resolved: Fix page corruption caused by racy check in __free_pages When we upgraded our kernel, we started seeing some page corruption like the following consistently: BUG: Bad page state in process ganesha.nfsd pfn:1304ca page:0000000022261c55 refcount:0 mapcount:-128 mapping:0000000000000000 index:0x0 pfn:0x1304ca flags: 0x17ffffc0000000() raw: 0017ffffc0000000 ffff8a513ffd4c98 ffffeee24b35ec08 0000000000000000 raw: 0000000000000000 0000000000000001 00000000ffffff7f 0000000000000000 page dumped because: nonzero mapcount CPU: 0 PID: 15567 Comm: ganesha.nfsd Kdump: loaded Tainted: P B O 5.10.158-1.nutanix.20221209.el7.x86_64 #1 Hardware name: VMware, Inc. VMware Virtual Platform/440BX Desktop Reference Platform, BIOS 6.00 04/05/2016 Call Trace: dump_stack+0x74/0x96 bad_page.cold+0x63/0x94 check_new_page_bad+0x6d/0x80 rmqueue+0x46e/0x970 get_page_from_freelist+0xcb/0x3f0 ? _cond_resched+0x19/0x40 __alloc_pages_nodemask+0x164/0x300 alloc_pages_current+0x87/0xf0 skb_page_frag_refill+0x84/0x110 ... Sometimes, it would also show up as corruption in the free list pointer and cause crashes. After bisecting the issue, we found the issue started from commit e320d3012d25 ("mm/page_alloc.c: fix freeing non-compound pages"): if (put_page_testzero(page)) free_the_page(page, order); else if (!PageHead(page)) while (order-- > 0) free_the_page(page + (1 << order), order); So the problem is the check PageHead is racy because at this point we already dropped our reference to the page. So even if we came in with compound page, the page can already be freed and PageHead can return false and we will end up freeing all the tail pages causing double free.

Severity
medium
Software
Kernel
Fixed in
6.1.12
Published
2024-05-21

Affected versions

From: 5.16

Until: 6.1.12

Fixed in: 6.1.12

How to fix this CVE

Update your Linux kernel to version 6.1.12 or later to resolve a critical memory management race condition that causes page corruption. This vulnerability affects kernel versions 5.16 through 6.1.11 and can lead to data corruption and system instability. Apply the patch immediately through your distribution's package manager.

sudo dnf update kernel kernel-devel

Defensia detects this vulnerability

How to check if you are affected

  1. Check your current kernel version: uname -r
  2. Verify if you are running a vulnerable version between 5.16 and 6.1.11: if [[ $(uname -r | cut -d. -f1,2) == '5.16' ]] || [[ $(uname -r | cut -d. -f1,2) == '6.0' ]] || [[ $(uname -r | cut -d. -f1,2) == '6.1' && $(uname -r | cut -d. -f3) -lt 12 ]]; then echo 'VULNERABLE'; fi
  3. Search kernel logs for page corruption warnings: sudo dmesg | grep -i 'bad page state\|nonzero mapcount\|page corruption'
  4. Verify the patch has been applied by checking if the kernel version is 6.1.12 or later: uname -r | awk -F. '{if ($1 > 6 || ($1 == 6 && $2 > 1) || ($1 == 6 && $2 == 1 && $3 >= 12)) print "PATCHED"; else print "VULNERABLE"}'

FAQ

What is CVE-2023-52739?

This vulnerability is a race condition in the Linux kernel's page memory management subsystem that occurs during page deallocation. When a compound page is freed, a timing window allows the kernel to incorrectly identify it as a non-compound page, leading to double-free corruption of tail pages and potential system instability.

Is CVE-2023-52739 being actively exploited?

No, CVE-2023-52739 is not listed on the CISA Known Exploited Vulnerabilities catalog and has no publicly available exploits. However, it can be triggered through normal kernel memory operations under load.

What versions of Kernel are affected by CVE-2023-52739?

Linux kernel versions 5.16 through 6.1.11 are vulnerable. The vulnerability was introduced in commit e320d3012d25 and fixed in kernel 6.1.12.

How do I check if my server is vulnerable to CVE-2023-52739?

Run 'uname -r' to check your kernel version. If the output shows version 5.16.x, 6.0.x, or 6.1.x (where x is less than 12), your system is vulnerable and requires an update.

Does Defensia detect CVE-2023-52739?

Yes — Defensia's CVE advisory scanner compares installed package versions against the NVD database. If the Linux kernel is installed on a monitored server, CVE-2023-52739 will appear in your dashboard with remediation steps.

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CVE-2026-64439CVSS 9.8In the Linux kernel, the following vulnerability has been resolved: crypto: krb5 - filter out async aead implementations at alloc krb5_aead_encrypt(), krb5_aead_decrypt() in rfc3961_simplified.c and rfc8009_encrypt(), rfc8009_decrypt() in rfc8009_aes2.c set a NULL completion callback and treat any negative return from crypto_aead_{encrypt,decrypt}() as terminal, falling through to kfree_sensitive(buffer). When the encrypt_name resolves to an async AEAD instance the request returns -EINPROGRESS, the buffer is freed while the backend's worker still holds a pointer, and the worker dereferences the freed slab on completion. KASAN report under UML+SLUB with a synthetic async aead backend bound to krb5->encrypt_name: BUG: KASAN: slab-use-after-free in t5_stub_complete+0x7d/0xc7 The helpers were written synchronously, so filter the async instances out at allocation time instead of plumbing crypto_wait_req() through every call site. Reachable via net/rxrpc/rxgk.c, fs/afs/cm_security.c and net/ceph/crypto.c on systems with an async AEAD provider bound to the krb5 enctype name.
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References

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