Bug 1225768 (CVE-2024-36920)

Summary: VUL-0: CVE-2024-36920: kernel: scsi: mpi3mr: avoid memcpy field-spanning write WARNING
Product: [Novell Products] SUSE Security Incidents Reporter: SMASH SMASH <smash_bz>
Component: IncidentsAssignee: Security Team bot <security-team>
Status: RESOLVED WONTFIX QA Contact: Security Team bot <security-team>
Severity: Normal    
Priority: P3 - Medium CC: camila.matos, mhocko
Version: unspecified   
Target Milestone: ---   
Hardware: Other   
OS: Other   
URL: https://smash.suse.de/issue/408238/
Whiteboard: CVSSv3.1:SUSE:CVE-2024-36920:0.0:(AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:N)
Found By: Security Response Team Services Priority:
Business Priority: Blocker: ---
Marketing QA Status: --- IT Deployment: ---

Description SMASH SMASH 2024-05-31 17:09:55 UTC 
In the Linux kernel, the following vulnerability has been resolved:

scsi: mpi3mr: Avoid memcpy field-spanning write WARNING

When the "storcli2 show" command is executed for eHBA-9600, mpi3mr driver
prints this WARNING message:

  memcpy: detected field-spanning write (size 128) of single field "bsg_reply_buf->reply_buf" at drivers/scsi/mpi3mr/mpi3mr_app.c:1658 (size 1)
  WARNING: CPU: 0 PID: 12760 at drivers/scsi/mpi3mr/mpi3mr_app.c:1658 mpi3mr_bsg_request+0x6b12/0x7f10 [mpi3mr]

The cause of the WARN is 128 bytes memcpy to the 1 byte size array "__u8
replay_buf[1]" in the struct mpi3mr_bsg_in_reply_buf. The array is intended
to be a flexible length array, so the WARN is a false positive.

To suppress the WARN, remove the constant number '1' from the array
declaration and clarify that it has flexible length. Also, adjust the
memory allocation size to match the change.

References:
http://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2024-36920
https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2024/CVE-2024-36920.mbox
https://git.kernel.org/stable/c/5f0266044dc611563539705bff0b3e1545fbb6aa
https://git.kernel.org/stable/c/f09318244c6cafd10aca741b9c01e0a2c362d43a
https://git.kernel.org/stable/c/4d2772324f43cf5674ac3dbe3f74a7e656396716
https://git.kernel.org/stable/c/429846b4b6ce9853e0d803a2357bb2e55083adf0
https://www.cve.org/CVERecord?id=CVE-2024-36920
Comment 2 Michal Hocko 2024-06-17 11:53:28 UTC 
The changelog says
    The cause of the WARN is 128 bytes memcpy to the 1 byte size array "__u8
    replay_buf[1]" in the struct mpi3mr_bsg_in_reply_buf. The array is intended
    to be a flexible length array, so the WARN is a false positive.

so there is no real issue other than WARNING triggering which is not considered to be a security threat as we do not enable panic_on_warn nor we recommend enabling this on any production systems.