Bug 2536526 (CVE-2026-90416)

Summary: CVE-2026-90416 kernel: RDMA/mlx5: Fix stack out-of-bounds read in cc_params debugfs
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
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 RDMA/mlx5 component. The `get_param()` function, used for debugging congestion parameters, incorrectly formats a 32-bit unsigned integer as a signed integer. This can lead to a stack out-of-bounds read when a large value is processed, potentially causing unexpected system behavior or information disclosure.
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
Embargoed:

Description OSIDB Bzimport 2026-09-17 18:18:21 UTC 
In the Linux kernel, the following vulnerability has been resolved:

RDMA/mlx5: Fix stack out-of-bounds read in cc_params debugfs

get_param() reads a congestion parameter as a u32 but formats it with the
signed "%d" into an 11-byte stack buffer. A value with bit 31 set, such as
0x80000000, renders as "-2147483648\n" whose full length is 12. snprintf()
stores only 11 bytes yet returns 12, so simple_read_from_buffer() treats 12
bytes as valid and reads one byte past lbuf[].

Size the buffer for the widest unsigned decimal, format with "%u" to match
the u32, and use scnprintf() so the length passed to
simple_read_from_buffer() reflects the bytes actually stored.
Comment 1 gkamathe 2026-09-21 12:11:46 UTC 
Upstream advisory:
https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-90416.mbox