Bug 2546340 (CVE-2026-98170)

Summary: CVE-2026-98170 kernel: smb: client: fix OOB struct field reads in move_smb2_ea_to_cifs()
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security <prodsec-ir-bot>
Status: NEW --- QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: unspecifiedCC: akhatavk, aos-team-art-private, asdas, dpaolell, jdelft, jupierce, lgarciaa, mbiarnes, ppalepu, ppostler, prdhamdh, rhel-process-autobot, sghai, sidsharm, suppawar, vlaad, watson-tool-maintainers
Target Milestone: ---Keywords: Security
Target Release: ---   
Hardware: All   
OS: Linux   
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Doc Text:
A flaw was found in the Linux kernel's SMB client. When processing extended file attributes returned by a server, insufficient buffer validation allows the kernel to read data past the allocated boundaries. A malicious or compromised server could exploit this issue by returning a malformed response, potentially causing a system crash resulting in a Denial of Service (DoS) or disclosing sensitive kernel memory.
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
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Description OSIDB Bzimport 2026-10-06 08:59:17 UTC 
In the Linux kernel, the following vulnerability has been resolved:

smb: client: fix OOB struct field reads in move_smb2_ea_to_cifs()

In move_smb2_ea_to_cifs(), the while (src_size > 0) loop condition is
insufficient. It allows iteration to continue even if the remaining
src_size is too small to contain a complete smb2_ea_info structure.
Consequently, reads of ea_name_length and ea_value_length can occur
out-of-bounds.

Fix this by ensuring src_size >= sizeof(*src) before attempting to read
any structure fields. Additionally, reject any next_entry_offset that is
smaller than sizeof(*src) or that would advance the pointer beyond the
available buffer.

Note that for calls where the server returns a malformed EA list, the
error returned to userspace changes from -ENODATA (getxattr) or
-ERANGE (listxattr) to -EIO. This correctly signals a server protocol
error rather than misleadingly indicating "attribute not present" or
"output buffer too small".
Comment 1 Mauro Matteo Cascella 2026-10-06 19:19:59 UTC 
Upstream advisory:
https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-98170.mbox