Description

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).

Severity

 

CVSS Version 4.0 CVSS Version 3.x CVSS Version 2.0

CVSS 4.0 Severity and Metrics:

NIST: NVD

N/A

NVD assessment not yet provided.

NVD Analysts use publicly available information to associate vector strings and CVSS scores. We also display any CVSS information provided within the CVE List from the CNA.

Note: NVD Analysts have not published a CVSS score for this CVE at this time. NVD Analysts use publicly available information at the time of analysis to associate CVSS vector strings.

CVSS 3.x Severity and Metrics:

NIST: NVD

Base Score:  N/A

NVD assessment not yet provided.

NVD Analysts use publicly available information to associate vector strings and CVSS scores. We also display any CVSS information provided within the CVE List from the CNA.

Note: NVD Analysts have not published a CVSS score for this CVE at this time. NVD Analysts use publicly available information at the time of analysis to associate CVSS vector strings.

CVSS 2.0 Severity and Metrics:

NIST: NVD

Base Score: N/A

NVD assessment not yet provided.

NVD Analysts use publicly available information to associate vector strings and CVSS scores. We also display any CVSS information provided within the CVE List from the CNA.

Note: NVD Analysts have not published a CVSS score for this CVE at this time. NVD Analysts use publicly available information at the time of analysis to associate CVSS vector strings.

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 

kernel.org https://git.kernel.org/stable/c/65f2ced695982ccd516196d0a9447d85dbe2eed5 [No types assigned]

kernel.org https://git.kernel.org/stable/c/844b4e132f57f1333dc79feaa035075a096762e4 [No types assigned]

kernel.org https://git.kernel.org/stable/c/e45deec35bf7f1f4f992a707b2d04a8c162f2240 [No types assigned]

kernel.org https://git.kernel.org/stable/c/f3dc1bdb6b0b0693562c7c54a6c28bafa608ba3c [No types assigned]