GHSA-3VM4-73FJ-2J43
Vulnerability from github – Published: 2025-10-14 21:30 – Updated: 2025-10-14 21:30In the Linux kernel, the following vulnerability has been resolved:
powerpc: Fix virt_addr_valid() for 64-bit Book3E & 32-bit
mpe: On 64-bit Book3E vmalloc space starts at 0x8000000000000000.
Because of the way __pa() works we have: __pa(0x8000000000000000) == 0, and therefore virt_to_pfn(0x8000000000000000) == 0, and therefore virt_addr_valid(0x8000000000000000) == true
Which is wrong, virt_addr_valid() should be false for vmalloc space. In fact all vmalloc addresses that alias with a valid PFN will return true from virt_addr_valid(). That can cause bugs with hardened usercopy as described below by Kefeng Wang:
When running ethtool eth0 on 64-bit Book3E, a BUG occurred:
usercopy: Kernel memory exposure attempt detected from SLUB object not in SLUB page?! (offset 0, size 1048)!
kernel BUG at mm/usercopy.c:99
...
usercopy_abort+0x64/0xa0 (unreliable)
__check_heap_object+0x168/0x190
__check_object_size+0x1a0/0x200
dev_ethtool+0x2494/0x2b20
dev_ioctl+0x5d0/0x770
sock_do_ioctl+0xf0/0x1d0
sock_ioctl+0x3ec/0x5a0
__se_sys_ioctl+0xf0/0x160
system_call_exception+0xfc/0x1f0
system_call_common+0xf8/0x200
The code shows below,
data = vzalloc(array_size(gstrings.len, ETH_GSTRING_LEN));
copy_to_user(useraddr, data, gstrings.len * ETH_GSTRING_LEN))
The data is alloced by vmalloc(), virt_addr_valid(ptr) will return true on 64-bit Book3E, which leads to the panic.
As commit 4dd7554a6456 ("powerpc/64: Add VIRTUAL_BUG_ON checks for __va and __pa addresses") does, make sure the virt addr above PAGE_OFFSET in the virt_addr_valid() for 64-bit, also add upper limit check to make sure the virt is below high_memory.
Meanwhile, for 32-bit PAGE_OFFSET is the virtual address of the start of lowmem, high_memory is the upper low virtual address, the check is suitable for 32-bit, this will fix the issue mentioned in commit 602946ec2f90 ("powerpc: Set max_mapnr correctly") too.
On 32-bit there is a similar problem with high memory, that was fixed in commit 602946ec2f90 ("powerpc: Set max_mapnr correctly"), but that commit breaks highmem and needs to be reverted.
We can't easily fix __pa(), we have code that relies on its current behaviour. So for now add extra checks to virt_addr_valid().
For 64-bit Book3S the extra checks are not necessary, the combination of virt_to_pfn() and pfn_valid() should yield the correct result, but they are harmless.
[mpe: Add additional change log detail]
{
"affected": [],
"aliases": [
"CVE-2022-49067"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2025-02-26T07:00:43Z",
"severity": "MODERATE"
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\npowerpc: Fix virt_addr_valid() for 64-bit Book3E \u0026 32-bit\n\nmpe: On 64-bit Book3E vmalloc space starts at 0x8000000000000000.\n\nBecause of the way __pa() works we have:\n __pa(0x8000000000000000) == 0, and therefore\n virt_to_pfn(0x8000000000000000) == 0, and therefore\n virt_addr_valid(0x8000000000000000) == true\n\nWhich is wrong, virt_addr_valid() should be false for vmalloc space.\nIn fact all vmalloc addresses that alias with a valid PFN will return\ntrue from virt_addr_valid(). That can cause bugs with hardened usercopy\nas described below by Kefeng Wang:\n\n When running ethtool eth0 on 64-bit Book3E, a BUG occurred:\n\n usercopy: Kernel memory exposure attempt detected from SLUB object not in SLUB page?! (offset 0, size 1048)!\n kernel BUG at mm/usercopy.c:99\n ...\n usercopy_abort+0x64/0xa0 (unreliable)\n __check_heap_object+0x168/0x190\n __check_object_size+0x1a0/0x200\n dev_ethtool+0x2494/0x2b20\n dev_ioctl+0x5d0/0x770\n sock_do_ioctl+0xf0/0x1d0\n sock_ioctl+0x3ec/0x5a0\n __se_sys_ioctl+0xf0/0x160\n system_call_exception+0xfc/0x1f0\n system_call_common+0xf8/0x200\n\n The code shows below,\n\n data = vzalloc(array_size(gstrings.len, ETH_GSTRING_LEN));\n copy_to_user(useraddr, data, gstrings.len * ETH_GSTRING_LEN))\n\n The data is alloced by vmalloc(), virt_addr_valid(ptr) will return true\n on 64-bit Book3E, which leads to the panic.\n\n As commit 4dd7554a6456 (\"powerpc/64: Add VIRTUAL_BUG_ON checks for __va\n and __pa addresses\") does, make sure the virt addr above PAGE_OFFSET in\n the virt_addr_valid() for 64-bit, also add upper limit check to make\n sure the virt is below high_memory.\n\n Meanwhile, for 32-bit PAGE_OFFSET is the virtual address of the start\n of lowmem, high_memory is the upper low virtual address, the check is\n suitable for 32-bit, this will fix the issue mentioned in commit\n 602946ec2f90 (\"powerpc: Set max_mapnr correctly\") too.\n\nOn 32-bit there is a similar problem with high memory, that was fixed in\ncommit 602946ec2f90 (\"powerpc: Set max_mapnr correctly\"), but that\ncommit breaks highmem and needs to be reverted.\n\nWe can\u0027t easily fix __pa(), we have code that relies on its current\nbehaviour. So for now add extra checks to virt_addr_valid().\n\nFor 64-bit Book3S the extra checks are not necessary, the combination of\nvirt_to_pfn() and pfn_valid() should yield the correct result, but they\nare harmless.\n\n[mpe: Add additional change log detail]",
"id": "GHSA-3vm4-73fj-2j43",
"modified": "2025-10-14T21:30:25Z",
"published": "2025-10-14T21:30:25Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2022-49067"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/a3727c25eacd7e437c4f560957fa3a376fe93e6b"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/cbc065efcba000ad8f615f506ebe61b6d3c5145b"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/d36febbcd537fcc50284e8b89609632d0146529f"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/deab81144d5a043f42804207fb76cfbd8a806978"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/fddb88bd266f4513abab7c36bca98935c9148a98"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/ffa0b64e3be58519ae472ea29a1a1ad681e32f48"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H",
"type": "CVSS_V3"
}
]
}
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