[PATCH] RDMA/rxe: Fix UAF in ODP init error-handling path

[Peiyang He]

rxe_odp_mr_init_user() stores &umem_odp->umem in mr->umem before
calling rxe_odp_init_pages(). If rxe_odp_init_pages() fails,
rxe_odp_mr_init_user() releases umem_odp and returns an error.

rxe_reg_user_mr() then unwinds the error through rxe_cleanup(),
rxe_mr_cleanup(), ib_umem_release(mr->umem). There is an
IS_ERR_OR_NULL(umem) check at the start of ib_umem_release().
But since mr->umem is NOT reset to NULL in the error handling
path of rxe_odp_mr_init_user(), the check passes and it reads
already-freed fields like umem->is_dmabuf, causing UAF.

Fix the UAF by clearing mr->umem after releasing the failed
ODP umem so the MR cleanup path does not release it again.

Fixes: d03fb5c6599e ("RDMA/rxe: Allow registering MRs for On-Demand Paging")
Cc: stable@xxxxxxxxxxxxxxx
Assisted-by: Codex:gpt-5.6-sol
Signed-off-by: Peiyang He <peiyang_he@xxxxxxxxxxxxxxxx>
---
 drivers/infiniband/sw/rxe/rxe_odp.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/infiniband/sw/rxe/rxe_odp.c b/drivers/infiniband/sw/rxe/rxe_odp.c
index ff904d5e54a7..1b1c4a0c7110 100644
--- a/drivers/infiniband/sw/rxe/rxe_odp.c
+++ b/drivers/infiniband/sw/rxe/rxe_odp.c
@@ -114,6 +114,7 @@ int rxe_odp_mr_init_user(struct rxe_dev *rxe, u64 start, u64 length,
 	err = rxe_odp_init_pages(mr);
 	if (err) {
 		ib_umem_odp_release(umem_odp);
+		mr->umem = NULL;
 		return err;
 	}
 
-- 
2.43.0