aio: io_uring: Fix danger of completion getting reused before being read We called io_uring_cqe_seen(..., cqe) before reading cqe->res. That allows the completion to be reused, which in turn could lead to cqe->res being overwritten. The window for that is very narrow and the likelihood of it happening is very low, as we should never actually utilize all CQEs, but the consequences would be bad.
This bug was reported to me privately. Backpatch-through: 18 Discussion: https://postgr.es/m/bwo3e5lj2dgi2wzq4yvbyzu7nmwueczvvzioqsqo6azu6lm5oy@pbx75g2ach3p Branch ------ master Details ------- https://git.postgresql.org/pg/commitdiff/8077649907d40b9831358d0c5121a8c58267a988 Modified Files -------------- src/backend/storage/aio/method_io_uring.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-)
