linux-kernel - [PATCH v1] wifi: wext: propagate metadata on -E2BIG for GET ioctls

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Message-ID: <tencent_FE21EA217C7FF6B3CEAB5749F98F0267EC0A@qq.com>
Date: Thu,  7 Aug 2025 21:10:18 +0800
From: Callan Huang <luvings@...com>
To: johannes@...solutions.net
Cc: linux-wireless@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	luvings@...com
Subject: [PATCH v1] wifi: wext: propagate metadata on -E2BIG for GET ioctls

When GET ioctls encounter insufficient buffer (-E2BIG),
preserve u.data.length metadata in iwreq structure for size detection

Typical usage in userspace tools like 'iwlist wlan0 scanning':
- Detect required buffer size via u.data.length
- Implement retry logic with proper allocation

Signed-off-by: Callan Huang <luvings@...com>
---
 net/wireless/wext-core.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/net/wireless/wext-core.c b/net/wireless/wext-core.c
index c32a7c690..b4f72a49f 100644
--- a/net/wireless/wext-core.c
+++ b/net/wireless/wext-core.c
@@ -1075,7 +1075,7 @@ int wext_handle_ioctl(struct net *net, unsigned int cmd, void __user *arg)
 	ret = wext_ioctl_dispatch(net, &iwr, cmd, &info,
 				  ioctl_standard_call,
 				  ioctl_private_call);
-	if (ret >= 0 &&
+	if ((ret >= 0 || ret == -E2BIG) &&
 	    IW_IS_GET(cmd) &&
 	    copy_to_user(arg, &iwr, sizeof(struct iwreq)))
 		return -EFAULT;
@@ -1138,7 +1138,7 @@ int compat_wext_handle_ioctl(struct net *net, unsigned int cmd,
 				  compat_standard_call,
 				  compat_private_call);
 
-	if (ret >= 0 &&
+	if ((ret >= 0 || ret == -E2BIG) &&
 	    IW_IS_GET(cmd) &&
 	    copy_to_user(argp, &iwr, sizeof(struct iwreq)))
 		return -EFAULT;
-- 
2.25.1