diff mbox series

[net-next,06/13] net-sysfs: use dev_addr_sem to remove races in address_show()

Message ID 20240207142629.3456570-7-edumazet@google.com (mailing list archive)
State Superseded
Delegated to: Netdev Maintainers
Headers show
Series net: complete dev_base_lock removal | expand

Checks

Context Check Description
netdev/series_format success Posting correctly formatted
netdev/tree_selection success Clearly marked for net-next, async
netdev/ynl success Generated files up to date; no warnings/errors; no diff in generated;
netdev/fixes_present success Fixes tag not required for -next series
netdev/header_inline success No static functions without inline keyword in header files
netdev/build_32bit success Errors and warnings before: 5172 this patch: 5172
netdev/build_tools success Errors and warnings before: 0 this patch: 0
netdev/cc_maintainers success CCed 4 of 4 maintainers
netdev/build_clang success Errors and warnings before: 1191 this patch: 1191
netdev/verify_signedoff success Signed-off-by tag matches author and committer
netdev/deprecated_api success None detected
netdev/check_selftest success No net selftest shell script
netdev/verify_fixes success No Fixes tag
netdev/build_allmodconfig_warn success Errors and warnings before: 5474 this patch: 5474
netdev/checkpatch success total: 0 errors, 0 warnings, 0 checks, 39 lines checked
netdev/build_clang_rust success No Rust files in patch. Skipping build
netdev/kdoc success Errors and warnings before: 0 this patch: 0
netdev/source_inline success Was 0 now: 0
netdev/contest fail net-next-2024-02-08--03-00 (tests: 774)

Commit Message

Eric Dumazet Feb. 7, 2024, 2:26 p.m. UTC 
Using dev_base_lock is not preventing from reading garbage.

Use dev_addr_sem instead.

Signed-off-by: Eric Dumazet <edumazet@google.com>
---
 include/linux/netdevice.h |  1 +
 net/core/dev.c            |  2 +-
 net/core/net-sysfs.c      | 10 +++++++---
 3 files changed, 9 insertions(+), 4 deletions(-)
diff mbox series

Patch

diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index bed8de91e91a4bd83fe80f6835643af68f1adc53..b9140499630fa84108a1f22a2987c0c1934e8f8d 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -4031,6 +4031,7 @@  int dev_set_mac_address(struct net_device *dev, struct sockaddr *sa,
 			struct netlink_ext_ack *extack);
 int dev_set_mac_address_user(struct net_device *dev, struct sockaddr *sa,
 			     struct netlink_ext_ack *extack);
+extern struct rw_semaphore dev_addr_sem;
 int dev_get_mac_address(struct sockaddr *sa, struct net *net, char *dev_name);
 int dev_get_port_parent_id(struct net_device *dev,
 			   struct netdev_phys_item_id *ppid, bool recurse);
diff --git a/net/core/dev.c b/net/core/dev.c
index 027d0b7976f337df885266aeab2c90fe631decf1..2b96d1ed7f481cbd022368b3f16608cce4c6bc49 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -8922,7 +8922,7 @@  int dev_set_mac_address(struct net_device *dev, struct sockaddr *sa,
 }
 EXPORT_SYMBOL(dev_set_mac_address);
 
-static DECLARE_RWSEM(dev_addr_sem);
+DECLARE_RWSEM(dev_addr_sem);
 
 int dev_set_mac_address_user(struct net_device *dev, struct sockaddr *sa,
 			     struct netlink_ext_ack *extack)
diff --git a/net/core/net-sysfs.c b/net/core/net-sysfs.c
index 678e4be690821c5cdb933f5e91af2247ebecb830..23ef2df549c3036a702f3be1dca1eda14ee5e76f 100644
--- a/net/core/net-sysfs.c
+++ b/net/core/net-sysfs.c
@@ -142,17 +142,21 @@  static ssize_t name_assign_type_show(struct device *dev,
 }
 static DEVICE_ATTR_RO(name_assign_type);
 
-/* use same locking rules as GIFHWADDR ioctl's */
+/* use same locking rules as GIFHWADDR ioctl's (dev_get_mac_address()) */
 static ssize_t address_show(struct device *dev, struct device_attribute *attr,
 			    char *buf)
 {
 	struct net_device *ndev = to_net_dev(dev);
 	ssize_t ret = -EINVAL;
 
-	read_lock(&dev_base_lock);
+	down_read(&dev_addr_sem);
+
+	rcu_read_lock();
 	if (dev_isalive(ndev))
 		ret = sysfs_format_mac(buf, ndev->dev_addr, ndev->addr_len);
-	read_unlock(&dev_base_lock);
+	rcu_read_unlock();
+
+	up_read(&dev_addr_sem);
 	return ret;
 }
 static DEVICE_ATTR_RO(address);