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68b3d4dbaf
The commit that introduced the receive-path latency trace added the
clearing of inc->i_rx_lat_trace[] to rds_inc_init() only;
rds_inc_path_init() never got it.
That asymmetry matters for the one caller that reuses memory:
rds_tcp_data_recv() carves its rds_tcp_incoming out of a kmem_cache
with no zeroing and no constructor, so after rds_inc_path_init() the
array still holds the timestamps of whatever message previously
occupied that slab object. No stale value is user-visible today -
every message that reaches the socket happens to overwrite all four
slots (RX_HDR at allocation, RX_START when the header completes,
RX_END at delivery, RX_CMSG at recvmsg time) before
RDS_CMSG_RXPATH_LATENCY reads them back as deltas - but that is a
property of the current writers, not of the init contract, and a
future trace point or an early-exit path would expose another
message's timestamps to userspace.
Clear the array in rds_inc_path_init() too, so both init helpers
leave the inc fully initialized. memset is the form the clearing
already takes on the rds_inc_init() side since commit 1635bb548f
("net: rds: use memset to optimize the recv"). Hardening only; no
user-visible bug in the current code.
Assisted-by: Claude-Code:claude-fable-5
Signed-off-by: Allison Henderson <achender@kernel.org>
Reviewed-by: Simon Horman <horms@kernel.org>
Link: https://patch.msgid.link/20260810055631.299558-1-achender@kernel.org
Signed-off-by: Paolo Abeni <pabeni@redhat.com>