usb: gadget: configfs: Fix OOB read on empty string write

commit 3014168731b7930300aab656085af784edc861f6 upstream.

When writing an empty string to either 'qw_sign' or 'landingPage'
sysfs attributes, the store functions attempt to access page[l - 1]
before validating that the length 'l' is greater than zero.

This patch fixes the vulnerability by adding a check at the beginning
of os_desc_qw_sign_store() and webusb_landingPage_store() to handle
the zero-length input case gracefully by returning immediately.

Signed-off-by: Xinyu Liu <katieeliu@tencent.com>
Cc: stable <stable@kernel.org>
Link: https://lore.kernel.org/r/tencent_B1C9481688D0E95E7362AB2E999DE8048207@qq.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Xinyu Liu
2025-07-09 11:55:33 +08:00
committed by Greg Kroah-Hartman
parent ec35a7125d
commit 58bdd51601

View File

@@ -1062,6 +1062,8 @@ static ssize_t webusb_landingPage_store(struct config_item *item, const char *pa
unsigned int bytes_to_strip = 0;
int l = len;
if (!len)
return len;
if (page[l - 1] == '\n') {
--l;
++bytes_to_strip;
@@ -1185,6 +1187,8 @@ static ssize_t os_desc_qw_sign_store(struct config_item *item, const char *page,
struct gadget_info *gi = os_desc_item_to_gadget_info(item);
int res, l;
if (!len)
return len;
l = min((int)len, OS_STRING_QW_SIGN_LEN >> 1);
if (page[l - 1] == '\n')
--l;