In the Linux kernel, the following vulnerability has been resolved:
qede: fix off-by-one in BD ring consumption on build_skb failure
qede_rx_build_skb() and qede_tpa_rx_build_skb() do not check for a
NULL return from qede_build_skb(). When it returns NULL under memory
pressure, the functions still consume a BD from the ring before
returning NULL. The callers then recycle additional BDs, resulting in
one extra BD being consumed (off-by-one). This desynchronizes the BD
ring, which can corrupt DMA page reference counts and lead to SLUB
freelist corruption.
Commit 4e910dbe3650 ("qede: confirm skb is allocated before using")
added a NULL check inside qede_build_skb() to prevent a NULL pointer
dereference, but did not address the missing NULL checks in the
callers, making this off-by-one reachable.
Fix this by adding NULL checks for the return value of
qede_build_skb() in both qede_rx_build_skb() and
qede_tpa_rx_build_skb(), returning NULL immediately before any BD ring
manipulation.
CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
CVSS Score: 9.8
AV:N - The bug is in the qede NIC RX fastpath reached when remote Ethernet frames are received, hardware posts completion queue entries, and NAPI runs qede_poll() -> qede_rx_int() -> qede_rx_process_cqe()/qede_tpa_start() into qede_rx_build_skb() or qede_tpa_rx_build_skb().
AC:L - An attacker can reliably trigger build_skb() NULL returns by flooding the interface with frames larger than rx_copybreak (256 bytes) to exhaust GFP_ATOMIC skb slab allocations, then the off-by-one BD consumption desynchronizes the ring without races or victim-specific state.
PR:N - No local account, capability, or authentication is required; any unauthenticated remote host that can send IP/Ethernet traffic to a server using a Marvell/QLogic FastLinQ qede NIC can hit the vulnerable RX/TPA handlers.
UI:N - Exploitation requires no victim interaction beyond normal network operation; packet reception, MSI-X interrupt handling, and NAPI polling process attacker-supplied frames automatically in kernel context.
S:U - The flaw corrupts kernel heap metadata (DMA page refcounts and SLUB freelists) within the host kernel security boundary; it does not by itself cross VM, container, or IOMMU isolation boundaries.
C:H - BD ring desynchronization corrupts DMA page reference counts and can corrupt SLUB freelists; this class of kernel heap corruption is exploitable for arbitrary kernel memory reads and information disclosure beyond a simple crash.
I:H - SLUB freelist corruption from mismatched BD ring consumption enables arbitrary kernel memory writes and control-flow hijacking primitives, supporting local privilege escalation or arbitrary code execution in kernel context.
A:H - Reference-count and SLUB corruption from the desynchronized BD ring can cause kernel BUG/oops/panic or a wedged RX datapath, resulting in complete loss of host availability on affected systems.
| Attack Vector |
Network |
Scope |
Unchanged |
| Attack Complexity |
Low |
Confidentiality Impact |
High |
| Privileges Required |
None |
Integrity Impact |
High |
| User Interaction |
None |
Availability Impact |
High |
AV:N - The bug is in the qede NIC RX fastpath reached when remote Ethernet frames are received, hardware posts completion queue entries, and NAPI runs qede_poll() -> qede_rx_int() -> qede_rx_process_cqe()/qede_tpa_start() into qede_rx_build_skb() or qede_tpa_rx_build_skb().
AC:L - An attacker can reliably trigger build_skb() NULL returns by flooding the interface with frames larger than rx_copybreak (256 bytes) to exhaust GFP_ATOMIC skb slab allocations, then the off-by-one BD consumption desynchronizes the ring without races or victim-specific state.
PR:N - No local account, capability, or authentication is required; any unauthenticated remote host that can send IP/Ethernet traffic to a server using a Marvell/QLogic FastLinQ qede NIC can hit the vulnerable RX/TPA handlers.
UI:N - Exploitation requires no victim interaction beyond normal network operation; packet reception, MSI-X interrupt handling, and NAPI polling process attacker-supplied frames automatically in kernel context.
S:U - The flaw corrupts kernel heap metadata (DMA page refcounts and SLUB freelists) within the host kernel security boundary; it does not by itself cross VM, container, or IOMMU isolation boundaries.
C:H - BD ring desynchronization corrupts DMA page reference counts and can corrupt SLUB freelists; this class of kernel heap corruption is exploitable for arbitrary kernel memory reads and information disclosure beyond a simple crash.
I:H - SLUB freelist corruption from mismatched BD ring consumption enables arbitrary kernel memory writes and control-flow hijacking primitives, supporting local privilege escalation or arbitrary code execution in kernel context.
A:H - Reference-count and SLUB corruption from the desynchronized BD ring can cause kernel BUG/oops/panic or a wedged RX datapath, resulting in complete loss of host availability on affected systems.
CVSS 3.1