[PATCH v1,for-rc] RDMA/siw: free siw_base_qp in kref release routine

[PATCH v1,for-rc] RDMA/siw: free siw_base_qp in kref release routine

[Krishnamraju Eraparaju]

As siw_free_qp() is the last routine to access 'siw_base_qp' structure,
freeing this structure early in siw_destroy_qp() could cause
touch-after-free issue.
Hence, moved kfree(siw_base_qp) from siw_destroy_qp() to siw_free_qp().

Fixes: 303ae1cdfdf7 ("rdma/siw: application interface")
Signed-off-by: Krishnamraju Eraparaju <krishna2@chelsio.com>
---
v0 -> v1:
- added "Fixes" line.
---
 drivers/infiniband/sw/siw/siw_qp.c    | 2 ++
 drivers/infiniband/sw/siw/siw_verbs.c | 2 --
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/infiniband/sw/siw/siw_qp.c b/drivers/infiniband/sw/siw/siw_qp.c
index 430314c8abd9..c317f6e18ea8 100644
--- a/drivers/infiniband/sw/siw/siw_qp.c
+++ b/drivers/infiniband/sw/siw/siw_qp.c
@@ -1305,6 +1305,7 @@ int siw_qp_add(struct siw_device *sdev, struct siw_qp *qp)
 void siw_free_qp(struct kref *ref)
 {
 	struct siw_qp *found, *qp = container_of(ref, struct siw_qp, ref);
+	struct siw_base_qp *siw_base_qp = to_siw_base_qp(qp->ib_qp);
 	struct siw_device *sdev = qp->sdev;
 	unsigned long flags;
 
@@ -1327,4 +1328,5 @@ void siw_free_qp(struct kref *ref)
 	atomic_dec(&sdev->num_qp);
 	siw_dbg_qp(qp, "free QP\n");
 	kfree_rcu(qp, rcu);
+	kfree(siw_base_qp);
 }
diff --git a/drivers/infiniband/sw/siw/siw_verbs.c b/drivers/infiniband/sw/siw/siw_verbs.c
index 869e02b69a01..b18a677832e1 100644
--- a/drivers/infiniband/sw/siw/siw_verbs.c
+++ b/drivers/infiniband/sw/siw/siw_verbs.c
@@ -604,7 +604,6 @@ int siw_verbs_modify_qp(struct ib_qp *base_qp, struct ib_qp_attr *attr,
 int siw_destroy_qp(struct ib_qp *base_qp, struct ib_udata *udata)
 {
 	struct siw_qp *qp = to_siw_qp(base_qp);
-	struct siw_base_qp *siw_base_qp = to_siw_base_qp(base_qp);
 	struct siw_ucontext *uctx =
 		rdma_udata_to_drv_context(udata, struct siw_ucontext,
 					  base_ucontext);
@@ -641,7 +640,6 @@ int siw_destroy_qp(struct ib_qp *base_qp, struct ib_udata *udata)
 	qp->scq = qp->rcq = NULL;
 
 	siw_qp_put(qp);
-	kfree(siw_base_qp);
 
 	return 0;
 }
-- 
2.23.0.rc0

Re: [PATCH v1,for-rc] RDMA/siw: free siw_base_qp in kref release routine

[Doug Ledford]

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On Mon, 2019-10-07 at 16:12 +0530, Krishnamraju Eraparaju wrote:
> As siw_free_qp() is the last routine to access 'siw_base_qp'
> structure,
> freeing this structure early in siw_destroy_qp() could cause
> touch-after-free issue.
> Hence, moved kfree(siw_base_qp) from siw_destroy_qp() to
> siw_free_qp().
> 
> Fixes: 303ae1cdfdf7 ("rdma/siw: application interface")
> Signed-off-by: Krishnamraju Eraparaju <krishna2@chelsio.com>

Thanks, applied to for-rc.

-- 
Doug Ledford <dledford@redhat.com>
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