linux-kernel - [PATCH] PCI: Fix memory leak in pci_register_io

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Date:   Tue,  2 Feb 2021 11:03:32 +0100
From:   Geert Uytterhoeven <geert+renesas@...der.be>
To:     Bjorn Helgaas <bhelgaas@...gle.com>,
        John Garry <john.garry@...wei.com>,
        Arnd Bergmann <arnd@...db.de>
Cc:     linux-pci@...r.kernel.org, linux-renesas-soc@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        Geert Uytterhoeven <geert+renesas@...der.be>
Subject: [PATCH] PCI: Fix memory leak in pci_register_io_range()

Kmemleak reports:

    unreferenced object 0xc328de40 (size 64):
      comm "kworker/1:1", pid 21, jiffies 4294938212 (age 1484.670s)
      hex dump (first 32 bytes):
        00 00 00 00 00 00 00 00 e0 d8 fc eb 00 00 00 00  ................
        00 00 10 fe 00 00 00 00 00 00 00 00 00 00 00 00  ................

    backtrace:
      [<ad758d10>] pci_register_io_range+0x3c/0x80
      [<2c7f139e>] of_pci_range_to_resource+0x48/0xc0
      [<f079ecc8>] devm_of_pci_get_host_bridge_resources.constprop.0+0x2ac/0x3ac
      [<e999753b>] devm_of_pci_bridge_init+0x60/0x1b8
      [<a895b229>] devm_pci_alloc_host_bridge+0x54/0x64
      [<e451ddb0>] rcar_pcie_probe+0x2c/0x644

In case a PCI host driver's probe is deferred, the same I/O range may be
allocated again, and be ignored, causing a memory leak.

Fix this by (a) letting logic_pio_register_range() return -EEXIST if the
passed range already exists, so pci_register_io_range() will free it,
and by (b) making pci_register_io_range() not consider -EEXIST an error
condition.

Signed-off-by: Geert Uytterhoeven <geert+renesas@...der.be>
---
 drivers/pci/pci.c | 4 ++++
 lib/logic_pio.c   | 3 +++
 2 files changed, 7 insertions(+)

diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index 09b03cfba8894955..c651003e304a2b71 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -4037,6 +4037,10 @@ int pci_register_io_range(struct fwnode_handle *fwnode, phys_addr_t addr,
 	ret = logic_pio_register_range(range);
 	if (ret)
 		kfree(range);
+
+	/* Ignore duplicates due to deferred probing */
+	if (ret == -EEXIST)
+		ret = 0;
 #endif
 
 	return ret;
diff --git a/lib/logic_pio.c b/lib/logic_pio.c
index f32fe481b4922bc1..07b4b9a1f54b6bf5 100644
--- a/lib/logic_pio.c
+++ b/lib/logic_pio.c
@@ -28,6 +28,8 @@ static DEFINE_MUTEX(io_range_mutex);
  * @new_range: pointer to the IO range to be registered.
  *
  * Returns 0 on success, the error code in case of failure.
+ * If the range already exists, -EEXIST will be returned, which should be
+ * considered a success.
  *
  * Register a new IO range node in the IO range list.
  */
@@ -51,6 +53,7 @@ int logic_pio_register_range(struct logic_pio_hwaddr *new_range)
 	list_for_each_entry(range, &io_range_list, list) {
 		if (range->fwnode == new_range->fwnode) {
 			/* range already there */
+			ret = -EEXIST;
 			goto end_register;
 		}
 		if (range->flags == LOGIC_PIO_CPU_MMIO &&
-- 
2.25.1