[PATCH AUTOSEL for 4.15 54/78] PCI: endpoint: Fix find_first_zero_bit() usage

[Sasha Levin]

From: Niklas Cassel <niklas.cassel@xxxxxxxx>

[ Upstream commit 35ad61921f495ee14915d185de79478c1737b4da ]

find_first_zero_bit()'s parameter 'size' is defined in bits,
not in bytes.

Calling find_first_zero_bit() with the wrong size unit
will lead to insidious bugs.

Fix this by calling find_first_zero_bit() with size BITS_PER_LONG,
rather than sizeof() and add missing find_first_zero_bit() return
handling.

Fixes: d74679911610 ("PCI: endpoint: Introduce configfs entry for configuring EP functions")
Signed-off-by: Niklas Cassel <niklas.cassel@xxxxxxxx>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@xxxxxxx>
Acked-by: Kishon Vijay Abraham I <kishon@xxxxxx>
Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxxxx>
---
 drivers/pci/endpoint/pci-ep-cfs.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/pci/endpoint/pci-ep-cfs.c b/drivers/pci/endpoint/pci-ep-cfs.c
index 4f74386c1ced..5508cd32afcd 100644
--- a/drivers/pci/endpoint/pci-ep-cfs.c
+++ b/drivers/pci/endpoint/pci-ep-cfs.c
@@ -109,7 +109,10 @@ static int pci_epc_epf_link(struct config_item *epc_item,
 		goto err_add_epf;
 
 	func_no = find_first_zero_bit(&epc_group->function_num_map,
-				      sizeof(epc_group->function_num_map));
+				      BITS_PER_LONG);
+	if (func_no >= BITS_PER_LONG)
+		return -EINVAL;
+
 	set_bit(func_no, &epc_group->function_num_map);
 	epf->func_no = func_no;
 
-- 
2.14.1