linux-kernel - [PATCH 1/2] pci: host: pci-hyperv: Replace GFP_ATOMIC with GFP_KERNEL in hv_pci

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Date:   Sun, 18 Mar 2018 22:53:02 +0800
From:   Jia-Ju Bai <baijiaju1990@...il.com>
To:     kys@...rosoft.com, haiyangz@...rosoft.com, sthemmin@...rosoft.com,
        bhelgaas@...gle.com
Cc:     devel@...uxdriverproject.org, linux-pci@...r.kernel.org,
        linux-kernel@...r.kernel.org, Jia-Ju Bai <baijiaju1990@...il.com>
Subject: [PATCH 1/2] pci: host: pci-hyperv: Replace GFP_ATOMIC with GFP_KERNEL in hv_pci_onchannelcallback

hv_pci_onchannelcallback() is not called in atomic context.

The call chain ending up at hv_pci_onchannelcallback() is:
[1] hv_pci_onchannelcallback() <- hv_pci_probe()
hv_pci_probe() is only set as ".probe" in hv_driver 
structure "hv_pci_drv".

Despite never getting called from atomic context, 
hv_pci_onchannelcallback() calls kmalloc with GFP_ATOMIC, 
which waits busily for allocation.
GFP_ATOMIC is not necessary and can be replaced with GFP_KERNEL 
to avoid busy waiting.

This is found by a static analysis tool named DCNS written by myself.

Signed-off-by: Jia-Ju Bai <baijiaju1990@...il.com>
---
 drivers/pci/host/pci-hyperv.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/pci/host/pci-hyperv.c b/drivers/pci/host/pci-hyperv.c
index 0fe3ea1..c5c8a99 100644
--- a/drivers/pci/host/pci-hyperv.c
+++ b/drivers/pci/host/pci-hyperv.c
@@ -1887,7 +1887,7 @@ static void hv_pci_onchannelcallback(void *context)
 	struct pci_dev_incoming *dev_message;
 	struct hv_pci_dev *hpdev;
 
-	buffer = kmalloc(bufferlen, GFP_ATOMIC);
+	buffer = kmalloc(bufferlen, GFP_KERNEL);
 	if (!buffer)
 		return;
 
@@ -1899,7 +1899,7 @@ static void hv_pci_onchannelcallback(void *context)
 			kfree(buffer);
 			/* Handle large packet */
 			bufferlen = bytes_recvd;
-			buffer = kmalloc(bytes_recvd, GFP_ATOMIC);
+			buffer = kmalloc(bytes_recvd, GFP_KERNEL);
 			if (!buffer)
 				return;
 			continue;
-- 
1.9.1