net: mana: Fix TOCTOU double-fetch of hwc_msg_id from DMA buffer

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[ Upstream commit 35f0f0a253 ]

In mana_hwc_rx_event_handler(), resp->response.hwc_msg_id is read from
DMA-coherent memory and bounds-checked, then mana_hwc_handle_resp()
re-reads the same field from the same DMA buffer for test_bit() and
pointer arithmetic.

DMA-coherent memory is mapped uncacheable on x86 and is shared,
unencrypted, in Confidential VMs (SEV-SNP/TDX), so each load goes
directly to host-visible memory. A H/W can modify the value
between the check and the use, bypassing the bounds validation.

Fix this by reading hwc_msg_id exactly once using READ_ONCE() into a
stack-local variable in mana_hwc_rx_event_handler(), and passing the
validated value as a parameter to mana_hwc_handle_resp().

Fixes: ca9c54d2d6 ("net: mana: Add a driver for Microsoft Azure Network Adapter (MANA)")
Signed-off-by: Erni Sri Satya Vennela <ernis@linux.microsoft.com>
Link: https://patch.msgid.link/20260514194156.466823-1-ernis@linux.microsoft.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

...

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Erni Sri Satya Vennela 2026-05-14 12:41:51 -07:00 • committed by Greg Kroah-Hartman

parent 4f6072ce41

commit a201c66edf

1 changed files with 13 additions and 10 deletions

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drivers/net/ethernet/microsoft/mana/hw_channel.c

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