There is a race condition between ucma_close() and ucma_resolve_ip():
CPU0 CPU1
ucma_resolve_ip(): ucma_close():
ctx = ucma_get_ctx(file, cmd.id);
list_for_each_entry_safe(ctx, tmp, &file->ctx_list, list) {
mutex_lock(&mut);
idr_remove(&ctx_idr, ctx->id);
mutex_unlock(&mut);
...
mutex_lock(&mut);
if (!ctx->closing) {
mutex_unlock(&mut);
rdma_destroy_id(ctx->cm_id);
...
ucma_free_ctx(ctx);
ret = rdma_resolve_addr();
ucma_put_ctx(ctx);
Before idr_remove(), ucma_get_ctx() could still find the ctx
and after rdma_destroy_id(), rdma_resolve_addr() may still
access id_priv pointer. Also, ucma_put_ctx() may use ctx after
ucma_free_ctx() too.
ucma_close() should call ucma_put_ctx() too which tests the
refcnt and waits for the last one releasing it. The similar
pattern is already used by ucma_destroy_id().
Reported-and-tested-by: [email protected]
Reported-by: [email protected]
Cc: Jason Gunthorpe <[email protected]>
Cc: Doug Ledford <[email protected]>
Cc: Leon Romanovsky <[email protected]>
Signed-off-by: Cong Wang <[email protected]>
---
drivers/infiniband/core/ucma.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/drivers/infiniband/core/ucma.c b/drivers/infiniband/core/ucma.c
index 5f437d1570fb..21863ddde63e 100644
--- a/drivers/infiniband/core/ucma.c
+++ b/drivers/infiniband/core/ucma.c
@@ -1759,6 +1759,8 @@ static int ucma_close(struct inode *inode, struct file *filp)
mutex_lock(&mut);
if (!ctx->closing) {
mutex_unlock(&mut);
+ ucma_put_ctx(ctx);
+ wait_for_completion(&ctx->comp);
/* rdma_destroy_id ensures that no event handlers are
* inflight for that id before releasing it.
*/
--
2.14.4
On Wed, Sep 12, 2018 at 04:27:44PM -0700, Cong Wang wrote:
> There is a race condition between ucma_close() and ucma_resolve_ip():
>
> CPU0 CPU1
> ucma_resolve_ip(): ucma_close():
>
> ctx = ucma_get_ctx(file, cmd.id);
>
> list_for_each_entry_safe(ctx, tmp, &file->ctx_list, list) {
> mutex_lock(&mut);
> idr_remove(&ctx_idr, ctx->id);
> mutex_unlock(&mut);
> ...
> mutex_lock(&mut);
> if (!ctx->closing) {
> mutex_unlock(&mut);
> rdma_destroy_id(ctx->cm_id);
> ...
> ucma_free_ctx(ctx);
>
> ret = rdma_resolve_addr();
> ucma_put_ctx(ctx);
>
> Before idr_remove(), ucma_get_ctx() could still find the ctx
> and after rdma_destroy_id(), rdma_resolve_addr() may still
> access id_priv pointer. Also, ucma_put_ctx() may use ctx after
> ucma_free_ctx() too.
>
> ucma_close() should call ucma_put_ctx() too which tests the
> refcnt and waits for the last one releasing it. The similar
> pattern is already used by ucma_destroy_id().
>
> Reported-and-tested-by: [email protected]
> Reported-by: [email protected]
> Cc: Jason Gunthorpe <[email protected]>
> Cc: Doug Ledford <[email protected]>
> Cc: Leon Romanovsky <[email protected]>
> Signed-off-by: Cong Wang <[email protected]>
> ---
> drivers/infiniband/core/ucma.c | 2 ++
> 1 file changed, 2 insertions(+)
>
Thanks,
Reviewed-by: Leon Romanovsky <[email protected]>
On Wed, 2018-09-12 at 16:27 -0700, Cong Wang wrote:
> There is a race condition between ucma_close() and ucma_resolve_ip():
>
> CPU0 CPU1
> ucma_resolve_ip(): ucma_close():
>
> ctx = ucma_get_ctx(file, cmd.id);
>
> list_for_each_entry_safe(ctx, tmp, &file->ctx_list, list) {
> mutex_lock(&mut);
> idr_remove(&ctx_idr, ctx->id);
> mutex_unlock(&mut);
> ...
> mutex_lock(&mut);
> if (!ctx->closing) {
> mutex_unlock(&mut);
> rdma_destroy_id(ctx->cm_id);
> ...
> ucma_free_ctx(ctx);
>
> ret = rdma_resolve_addr();
> ucma_put_ctx(ctx);
>
> Before idr_remove(), ucma_get_ctx() could still find the ctx
> and after rdma_destroy_id(), rdma_resolve_addr() may still
> access id_priv pointer. Also, ucma_put_ctx() may use ctx after
> ucma_free_ctx() too.
>
> ucma_close() should call ucma_put_ctx() too which tests the
> refcnt and waits for the last one releasing it. The similar
> pattern is already used by ucma_destroy_id().
>
> Reported-and-tested-by: [email protected]
> Reported-by: [email protected]
> Cc: Jason Gunthorpe <[email protected]>
> Cc: Doug Ledford <[email protected]>
> Cc: Leon Romanovsky <[email protected]>
> Signed-off-by: Cong Wang <[email protected]>
Thanks, applied to for-rc.
--
Doug Ledford <[email protected]>
GPG KeyID: B826A3330E572FDD
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