i3c: master: svc: bound IBI payload to the requested max_payload_len

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Summary

CVECVE-2026-80951
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-09-11 20:19:00 UTC
Updated2026-09-11 20:19:00 UTC
DescriptionIn the Linux kernel, the following vulnerability has been resolved: i3c: master: svc: bound IBI payload to the requested max_payload_len svc_i3c_master_handle_ibi() reads the IBI payload from the RX FIFO into the IBI slot. The loop is bounded by the hardware FIFO size (SVC_I3C_FIFO_SIZE), not by the slot size. slot->data points into the IBI pool, which i3c_generic_ibi_alloc_pool() sizes at max_payload_len per slot. svc_i3c_master_request_ibi() only rejects a max_payload_len larger than SVC_I3C_FIFO_SIZE, so a driver can request a smaller one. mctp-i3c requests 1. Each readsb() then copies the controller RXCOUNT bytes (up to 31) with no check against the slot size. A device that sends more bytes than the slot holds writes past slot->data, an out-of-bounds write into the IBI pool. Bound the loop by dev->ibi->max_payload_len and clamp each read to the space left in the slot, the same way dw-i3c does. A device can still send more than the requested payload. Flush the leftover bytes from the RX FIFO so they do not leak into the next transfer.

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected dd3c52846d5954acd43f0e771689302f27dadc28 f296a0d5907bf88314dfda67245f7f69d1552470 git Not specified
CNA Linux Linux affected dd3c52846d5954acd43f0e771689302f27dadc28 5697d779577e2786ff3348ae9b77020ac0cf0aab git Not specified
CNA Linux Linux affected dd3c52846d5954acd43f0e771689302f27dadc28 aac3c5aababc7fb69d5bf5b0cc52d308574e3a8c git Not specified
CNA Linux Linux affected dd3c52846d5954acd43f0e771689302f27dadc28 e2bda39d7f9f285ec803e200b5c1f17143d0b483 git Not specified
CNA Linux Linux affected 5.12 Not specified
CNA Linux Linux unaffected 5.12 semver Not specified
CNA Linux Linux unaffected 6.12.109 6.12.* semver Not specified
CNA Linux Linux unaffected 6.18.50 6.18.* semver Not specified
CNA Linux Linux unaffected 7.2.4 7.2.* semver Not specified
CNA Linux Linux unaffected 7.3-rc1 * original_commit_for_fix Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/aac3c5aababc7fb69d5bf5b0cc52d308574e3a8c 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/f296a0d5907bf88314dfda67245f7f69d1552470 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/5697d779577e2786ff3348ae9b77020ac0cf0aab 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/e2bda39d7f9f285ec803e200b5c1f17143d0b483 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
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