CVE-2024-44939: linux kernel Null Dereference — Fix

Description

In the Linux kernel, the following vulnerability has been resolved: jfs: fix null ptr deref in dtInsertEntry [syzbot reported] general protection fault, probably for non-canonical address 0xdffffc0000000001: 0000 [#1] PREEMPT SMP KASAN PTI KASAN: null-ptr-deref in range [0x0000000000000008-0x000000000000000f] CPU: 0 PID: 5061 Comm: syz-executor404 Not tainted 6.8.0-syzkaller-08951-gfe46a7dd189e #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/27/2024 RIP: 0010:dtInsertEntry+0xd0c/0x1780 fs/jfs/jfs_dtree.c:3713 ... [Analyze] In dtInsertEntry(), when the pointer h has the same value as p, after writing name in UniStrncpy_to_le(), p->header.flag will be cleared. This will cause the previously true judgment "p->header.flag & BT-LEAF" to change to no after writing the name operation, this leads to entering an incorrect branch and accessing the uninitialized object ih when judging this condition for the second time. [Fix] After got the page, check freelist first, if freelist == 0 then exit dtInsert() and return -EINVAL.

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CVSS v3.1 Score

5.5

MEDIUM

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Weakness Type (CWE)

CWE-476 CWE-476

Affected Products

Vendor	Product	Versions
linux	linux_kernel	< 6.6.47
linux	linux_kernel	6.7 — 6.10.6

References

Advisories & Patches

https://git.kernel.org/stable/c/53023ab11836ac56fd75f7a71ec1356e50920fa9 https://git.kernel.org/stable/c/6ea10dbb1e6c58384136e9adfd75f81951e423f6 https://git.kernel.org/stable/c/9c2ac38530d1a3ee558834dfa16c85a40fd0e702 https://git.kernel.org/stable/c/ce6dede912f064a855acf6f04a04cbb2c25b8c8c

Other References

https://git.kernel.org/stable/c/f98bf80b20f4a930589cda48a35f751a64fe0dc2 https://lists.debian.org/debian-lts-announce/2025/01/msg00001.html

Frequently Asked Questions

What is CVE-2024-44939? +

In the Linux kernel, the following vulnerability has been resolved: jfs: fix null ptr deref in dtInsertEntry [syzbot reported] general protection fault, probably for non-canonical address 0xdffffc0000000001: 0000 [#1] PREEMPT SMP KASAN PTI KASAN: null-ptr-deref in range [0x0000000000000008-0x000000000000000f] CPU: 0 PID: 5061 Comm: syz-executor404 Not tainted 6.8.0-syzkaller-08951-gfe46a7dd189e #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/27/2024 RIP: 0010:dtInsertEntry+0xd0c/0x1780 fs/jfs/jfs_dtree.c:3713 ... [Analyze] In dtInsertEntry(), when the pointer h has the same value as p, after writing name in UniStrncpy_to_le(), p->header.flag will be cleared. This will cause the previously true judgment "p->header.flag & BT-LEAF" to change to no after writing the name operation, this leads to entering an incorrect branch and accessing the uninitialized object ih when judging this condition for the second time. [Fix] After got the page, check freelist first, if freelist == 0 then exit dtInsert() and return -EINVAL. It has a CVSS v3.1 base score of 5.5 (MEDIUM).

How severe is CVE-2024-44939? +

CVE-2024-44939 has a CVSS v3.1 score of 5.5 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance.

What products are affected by CVE-2024-44939? +

CVE-2024-44939 affects products from linux, specifically: linux_kernel. Check the affected products table above for specific version ranges.

How do I check if I'm vulnerable to CVE-2024-44939? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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