This is a note to let you know that I've just added the patch titled
RDMA/rxe: Fix ref count error in check_rkey()
to the 6.3-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
rdma-rxe-fix-ref-count-error-in-check_rkey.patch
and it can be found in the queue-6.3 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit e8804b690adef0ef5a98efd0f5feabedda4b0d9a
Author: Bob Pearson <rpearsonhpe@xxxxxxxxx>
Date: Wed May 17 16:15:10 2023 -0500
RDMA/rxe: Fix ref count error in check_rkey()
[ Upstream commit b00683422fd79dd07c9b75efdce1660e5e19150e ]
There is a reference count error in error path code and a potential race
in check_rkey() in rxe_resp.c. When looking up the rkey for a memory
window the reference to the mw from rxe_lookup_mw() is dropped before a
reference is taken on the mr referenced by the mw. If the mr is destroyed
immediately after the call to rxe_put(mw) the mr pointer is unprotected
and may end up pointing at freed memory. The rxe_get(mr) call should take
place before the rxe_put(mw) call.
All errors in check_rkey() call rxe_put(mw) if mw is not NULL but it was
already called after the above. The mw pointer should be set to NULL after
the rxe_put(mw) call to prevent this from happening.
Fixes: cdd0b85675ae ("RDMA/rxe: Implement memory access through MWs")
Link: https://lore.kernel.org/r/20230517211509.1819998-1-rpearsonhpe@xxxxxxxxx
Signed-off-by: Bob Pearson <rpearsonhpe@xxxxxxxxx>
Signed-off-by: Jason Gunthorpe <jgg@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/drivers/infiniband/sw/rxe/rxe_resp.c b/drivers/infiniband/sw/rxe/rxe_resp.c
index 8c68340502769..4e8d8bec0010b 100644
--- a/drivers/infiniband/sw/rxe/rxe_resp.c
+++ b/drivers/infiniband/sw/rxe/rxe_resp.c
@@ -519,8 +519,9 @@ static enum resp_states check_rkey(struct rxe_qp *qp,
if (mw->access & IB_ZERO_BASED)
qp->resp.offset = mw->addr;
- rxe_put(mw);
rxe_get(mr);
+ rxe_put(mw);
+ mw = NULL;
} else {
mr = lookup_mr(qp->pd, access, rkey, RXE_LOOKUP_REMOTE);
if (!mr) {
