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Date: Wed, 17 Apr 2024 12:29:00 +0200 From: Greg Kroah-Hartman <gregkh@...uxfoundation.org> To: linux-cve-announce@...r.kernel.org Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org> Subject: CVE-2024-26885: bpf: Fix DEVMAP_HASH overflow check on 32-bit arches 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. The Linux kernel CVE team has assigned CVE-2024-26885 to this issue. Affected and fixed versions =========================== Issue introduced in 5.4 with commit 6f9d451ab1a3 and fixed in 5.10.214 with commit 225da02acdc9 Issue introduced in 5.4 with commit 6f9d451ab1a3 and fixed in 5.15.153 with commit c826502bed93 Issue introduced in 5.4 with commit 6f9d451ab1a3 and fixed in 6.1.83 with commit edf7990baa48 Issue introduced in 5.4 with commit 6f9d451ab1a3 and fixed in 6.6.23 with commit 250051acc21f Issue introduced in 5.4 with commit 6f9d451ab1a3 and fixed in 6.7.11 with commit 22079b3a4233 Issue introduced in 5.4 with commit 6f9d451ab1a3 and fixed in 6.8.2 with commit e89386f62ce9 Issue introduced in 5.4 with commit 6f9d451ab1a3 and fixed in 6.9-rc1 with commit 281d464a34f5 Please see https://www.kernel.org for a full list of currently supported kernel versions by the kernel community. Unaffected versions might change over time as fixes are backported to older supported kernel versions. The official CVE entry at https://cve.org/CVERecord/?id=CVE-2024-26885 will be updated if fixes are backported, please check that for the most up to date information about this issue. Affected files ============== The file(s) affected by this issue are: kernel/bpf/devmap.c Mitigation ========== The Linux kernel CVE team recommends that you update to the latest stable kernel version for this, and many other bugfixes. Individual changes are never tested alone, but rather are part of a larger kernel release. Cherry-picking individual commits is not recommended or supported by the Linux kernel community at all. If however, updating to the latest release is impossible, the individual changes to resolve this issue can be found at these commits: https://git.kernel.org/stable/c/225da02acdc97af01b6bc6ce1a3e5362bf01d3fb https://git.kernel.org/stable/c/c826502bed93970f2fd488918a7b8d5f1d30e2e3 https://git.kernel.org/stable/c/edf7990baa48de5097daa9ac02e06cb4c798a737 https://git.kernel.org/stable/c/250051acc21f9d4c5c595e4fcb55986ea08c4691 https://git.kernel.org/stable/c/22079b3a423382335f47d9ed32114e6c9fe88d7c https://git.kernel.org/stable/c/e89386f62ce9a9ab9a94835a9890883c23d9d52c https://git.kernel.org/stable/c/281d464a34f540de166cee74b723e97ac2515ec3
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