CVE-2024-26885

HIGH
Published Apr 17, 2024 Modified May 12, 2026 CWE-119

Description

In the Linux kernel, the following vulnerability has been resolved: bpf: Fix DEVMAP_HASH overflow check on 32-bit arches The devmap code allocates a number hash buckets equal to the next power of two of the max_entries value provided when creating the map. When rounding up to the next power of two, the 32-bit variable storing the number of buckets can overflow, and the code checks for overflow by checking if the truncated 32-bit value is equal to 0. However, on 32-bit arches the rounding up itself can overflow mid-way through, because it ends up doing a left-shift of 32 bits on an unsigned long value. If the size of an unsigned long is four bytes, this is undefined behaviour, so there is no guarantee that we'll end up with a nice and tidy 0-value at the end. Syzbot managed to turn this into a crash on arm32 by creating a DEVMAP_HASH with max_entries > 0x80000000 and then trying to update it. Fix this by moving the overflow check to before the rounding up operation.

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CVSS v3.1 Score

7.8
HIGH
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Weakness Type (CWE)

CWE-119 Buffer Overflow

Affected Products

Vendor Product
linux linux_kernel
linux linux_kernel
linux linux_kernel
linux linux_kernel
linux linux_kernel
linux linux_kernel

References

Advisories & Patches

https://git.kernel.org/stable/c/22079b3a423382335f47d9ed32114e6c9fe88d7c https://git.kernel.org/stable/c/250051acc21f9d4c5c595e4fcb55986ea08c4691 https://git.kernel.org/stable/c/281d464a34f540de166cee74b723e97ac2515ec3 https://git.kernel.org/stable/c/c826502bed93970f2fd488918a7b8d5f1d30e2e3 https://git.kernel.org/stable/c/e89386f62ce9a9ab9a94835a9890883c23d9d52c https://git.kernel.org/stable/c/edf7990baa48de5097daa9ac02e06cb4c798a737 https://git.kernel.org/stable/c/22079b3a423382335f47d9ed32114e6c9fe88d7c https://git.kernel.org/stable/c/225da02acdc97af01b6bc6ce1a3e5362bf01d3fb https://git.kernel.org/stable/c/250051acc21f9d4c5c595e4fcb55986ea08c4691 https://git.kernel.org/stable/c/281d464a34f540de166cee74b723e97ac2515ec3 https://git.kernel.org/stable/c/c826502bed93970f2fd488918a7b8d5f1d30e2e3 https://git.kernel.org/stable/c/e89386f62ce9a9ab9a94835a9890883c23d9d52c https://git.kernel.org/stable/c/edf7990baa48de5097daa9ac02e06cb4c798a737

Frequently Asked Questions

What is CVE-2024-26885? +
In the Linux kernel, the following vulnerability has been resolved: bpf: Fix DEVMAP_HASH overflow check on 32-bit arches The devmap code allocates a number hash buckets equal to the next power of two of the max_entries value provided when creating the map. When rounding up to the next power of two, the 32-bit variable storing the number of buckets can overflow, and the code checks for overflow by checking if the truncated 32-bit value is equal to 0. However, on 32-bit arches the rounding up itself can overflow mid-way through, because it ends up doing a left-shift of 32 bits on an unsigned long value. If the size of an unsigned long is four bytes, this is undefined behaviour, so there is no guarantee that we'll end up with a nice and tidy 0-value at the end. Syzbot managed to turn this into a crash on arm32 by creating a DEVMAP_HASH with max_entries > 0x80000000 and then trying to update it. Fix this by moving the overflow check to before the rounding up operation. It has a CVSS v3.1 base score of 7.8 (HIGH).
How severe is CVE-2024-26885? +
CVE-2024-26885 has a CVSS v3.1 score of 7.8 out of 10, rated HIGH. This is a high-severity vulnerability that should be prioritized for patching.
What products are affected by CVE-2024-26885? +
CVE-2024-26885 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-2024-26885? +
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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