[PATCH rdma-rc v1] IB/core: Fix potential NULL pointer dereference in pkey cache

[Leon Romanovsky <leon@kernel.org>]

From: Jack Morgenstein <jackm@dev.mellanox.co.il>

The IB core pkey cache is populated by procedure ib_cache_update().
Initially, the pkey cache pointer is NULL. ib_cache_update allocates
a buffer and populates it with the device's pkeys, via repeated calls
to procedure ib_query_pkey().

If there is a failure in populating the pkey buffer via ib_query_pkey(),
ib_cache_update does not replace the old pkey buffer cache with the
updated one -- it leaves the old cache as is.

Since initially the pkey buffer cache is NULL, when calling
ib_cache_update the first time, a failure in ib_query_pkey() will cause
the pkey buffer cache pointer to remain NULL.

In this situation, any calls subsequent to ib_get_cached_pkey(),
ib_find_cached_pkey(), or ib_find_cached_pkey_exact() will try to
dereference the NULL pkey cache pointer, causing a kernel panic.

Fix this by checking the ib_cache_update() return value.

Fixes: 8faea9fd4a39 ("RDMA/cache: Move the cache per-port data into the main ib_port_data")
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Jack Morgenstein <jackm@dev.mellanox.co.il>
Signed-off-by: Leon Romanovsky <leonro@mellanox.com>
---
Changelog:
v1: I rewrote the patch to take care of ib_cache_update() return value.
v0: https://lore.kernel.org/linux-rdma/20200426075811.129814-1-leon@kernel.org
---
 drivers/infiniband/core/cache.c | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/drivers/infiniband/core/cache.c b/drivers/infiniband/core/cache.c
index 717b798cddad..1cbebfa374a5 100644
--- a/drivers/infiniband/core/cache.c
+++ b/drivers/infiniband/core/cache.c
@@ -1553,10 +1553,17 @@ int ib_cache_setup_one(struct ib_device *device)
 	if (err)
 		return err;

-	rdma_for_each_port (device, p)
-		ib_cache_update(device, p, true);
+	rdma_for_each_port (device, p) {
+		err = ib_cache_update(device, p, true);
+		if (err)
+			goto out;
+	}

 	return 0;
+
+out:
+	ib_cache_release_one(device);
+	return err;
 }

 void ib_cache_release_one(struct ib_device *device)
--
2.26.2