ghsa-vc8w-q4f6-f3fg
Vulnerability from github
In the Linux kernel, the following vulnerability has been resolved:
cifs: Fix writeback data corruption
cifs writeback doesn't correctly handle the case where cifs_extend_writeback() hits a point where it is considering an additional folio, but this would overrun the wsize - at which point it drops out of the xarray scanning loop and calls xas_pause(). The problem is that xas_pause() advances the loop counter - thereby skipping that page.
What needs to happen is for xas_reset() to be called any time we decide we don't want to process the page we're looking at, but rather send the request we are building and start a new one.
Fix this by copying and adapting the netfslib writepages code as a temporary measure, with cifs writeback intending to be offloaded to netfslib in the near future.
This also fixes the issue with the use of filemap_get_folios_tag() causing retry of a bunch of pages which the extender already dealt with.
This can be tested by creating, say, a 64K file somewhere not on cifs (otherwise copy-offload may get underfoot), mounting a cifs share with a wsize of 64000, copying the file to it and then comparing the original file and the copy:
dd if=/dev/urandom of=/tmp/64K bs=64k count=1
mount //192.168.6.1/test /mnt -o user=...,pass=...,wsize=64000
cp /tmp/64K /mnt/64K
cmp /tmp/64K /mnt/64K
Without the fix, the cmp fails at position 64000 (or shortly thereafter).
{
"affected": [],
"aliases": [
"CVE-2024-27036"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2024-05-01T13:15:49Z",
"severity": null
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\ncifs: Fix writeback data corruption\n\ncifs writeback doesn\u0027t correctly handle the case where\ncifs_extend_writeback() hits a point where it is considering an additional\nfolio, but this would overrun the wsize - at which point it drops out of\nthe xarray scanning loop and calls xas_pause(). The problem is that\nxas_pause() advances the loop counter - thereby skipping that page.\n\nWhat needs to happen is for xas_reset() to be called any time we decide we\ndon\u0027t want to process the page we\u0027re looking at, but rather send the\nrequest we are building and start a new one.\n\nFix this by copying and adapting the netfslib writepages code as a\ntemporary measure, with cifs writeback intending to be offloaded to\nnetfslib in the near future.\n\nThis also fixes the issue with the use of filemap_get_folios_tag() causing\nretry of a bunch of pages which the extender already dealt with.\n\nThis can be tested by creating, say, a 64K file somewhere not on cifs\n(otherwise copy-offload may get underfoot), mounting a cifs share with a\nwsize of 64000, copying the file to it and then comparing the original file\nand the copy:\n\n dd if=/dev/urandom of=/tmp/64K bs=64k count=1\n mount //192.168.6.1/test /mnt -o user=...,pass=...,wsize=64000\n cp /tmp/64K /mnt/64K\n cmp /tmp/64K /mnt/64K\n\nWithout the fix, the cmp fails at position 64000 (or shortly thereafter).",
"id": "GHSA-vc8w-q4f6-f3fg",
"modified": "2024-05-01T15:30:35Z",
"published": "2024-05-01T15:30:35Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2024-27036"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/65f2ced695982ccd516196d0a9447d85dbe2eed5"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/844b4e132f57f1333dc79feaa035075a096762e4"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/e45deec35bf7f1f4f992a707b2d04a8c162f2240"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/f3dc1bdb6b0b0693562c7c54a6c28bafa608ba3c"
}
],
"schema_version": "1.4.0",
"severity": []
}