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.
History

Fri, 22 Nov 2024 12:00:00 +0000

Type Values Removed Values Added
References

Fri, 08 Nov 2024 16:00:00 +0000


Thu, 17 Oct 2024 14:30:00 +0000

Type Values Removed Values Added
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Thu, 17 Oct 2024 14:00:00 +0000


cve-icon MITRE

Status: PUBLISHED

Assigner: Linux

Published: 2024-04-17T10:27:40.300Z

Updated: 2024-12-19T08:49:29.194Z

Reserved: 2024-02-19T14:20:24.185Z

Link: CVE-2024-26885

cve-icon Vulnrichment

Updated: 2024-08-02T00:21:05.424Z

cve-icon NVD

Status : Modified

Published: 2024-04-17T11:15:10.210

Modified: 2024-11-21T09:03:17.910

Link: CVE-2024-26885

cve-icon Redhat

Severity : Low

Publid Date: 2024-04-17T00:00:00Z

Links: CVE-2024-26885 - Bugzilla