Linux Kernel
CVE-2025-40189
Lifecycle Timeline
2DescriptionCVE.org
In the Linux kernel, the following vulnerability has been resolved:
net: usb: lan78xx: Fix lost EEPROM read timeout error(-ETIMEDOUT) in lan78xx_read_raw_eeprom
Syzbot reported read of uninitialized variable BUG with following call stack.
lan78xx 8-1:1.0 (unnamed net_device) (uninitialized): EEPROM read operation timeout ============= BUG: KMSAN: uninit-value in lan78xx_read_eeprom drivers/net/usb/lan78xx.c:1095 [inline] BUG: KMSAN: uninit-value in lan78xx_init_mac_address drivers/net/usb/lan78xx.c:1937 [inline] BUG: KMSAN: uninit-value in lan78xx_reset+0x999/0x2cd0 drivers/net/usb/lan78xx.c:3241 lan78xx_read_eeprom drivers/net/usb/lan78xx.c:1095 [inline] lan78xx_init_mac_address drivers/net/usb/lan78xx.c:1937 [inline] lan78xx_reset+0x999/0x2cd0 drivers/net/usb/lan78xx.c:3241 lan78xx_bind+0x711/0x1690 drivers/net/usb/lan78xx.c:3766 lan78xx_probe+0x225c/0x3310 drivers/net/usb/lan78xx.c:4707
Local variable sig.i.i created at: lan78xx_read_eeprom drivers/net/usb/lan78xx.c:1092 [inline] lan78xx_init_mac_address drivers/net/usb/lan78xx.c:1937 [inline] lan78xx_reset+0x77e/0x2cd0 drivers/net/usb/lan78xx.c:3241 lan78xx_bind+0x711/0x1690 drivers/net/usb/lan78xx.c:3766
The function lan78xx_read_raw_eeprom failed to properly propagate EEPROM read timeout errors (-ETIMEDOUT). In the fallthrough path, it first attempted to restore the pin configuration for LED outputs and then returned only the status of that restore operation, discarding the original timeout error.
As a result, callers could mistakenly treat the data buffer as valid even though the EEPROM read had actually timed out with no data or partial data.
To fix this, handle errors in restoring the LED pin configuration separately. If the restore succeeds, return any prior EEPROM timeout error correctly to the caller.
AnalysisAI
In the Linux kernel, the following vulnerability has been resolved: net: usb: lan78xx: Fix lost EEPROM read timeout error(-ETIMEDOUT) in lan78xx_read_raw_eeprom Syzbot reported read of uninitialized. No vendor patch available.
Technical ContextAI
In the Linux kernel, the following vulnerability has been resolved: net: usb: lan78xx: Fix lost EEPROM read timeout error(-ETIMEDOUT) in lan78xx_read_raw_eeprom Syzbot reported read of uninitialized variable BUG with following call stack. lan78xx 8-1:1.0 (unnamed net_device) (uninitialized): EEPROM read operation timeout ============= BUG: KMSAN: uninit-value in lan78xx_read_eeprom drivers/net/usb/lan78xx.c:1095 [inline] BUG: KMSAN: uninit-value in lan78xx_init_mac_address drivers/net/usb/lan78xx.c:1937 [inline] BUG: KMSAN: uninit-value in lan78xx_reset+0x999/0x2cd0 drivers/net/usb/lan78xx.c:3241 lan78xx_read_eeprom drivers/net/usb/lan78xx.c:1095 [inline] lan78xx_init_mac_address drivers/net/usb/lan78xx.c:1937 [inline] lan78xx_reset+0x999/0x2cd0 drivers/net/usb/lan78xx.c:3241 lan78xx_bind+0x711/0x1690 drivers/net/usb/lan78xx.c:3766 lan78xx_probe+0x225c/0x3310 drivers/net/usb/lan78xx.c:4707 Local variable sig.i.i created at: lan78xx_read_eeprom drivers/net/usb/lan78xx.c:1092 [inline] lan78xx_init_mac_address drivers/net/usb/lan78xx.c:1937 [inline] lan78xx_reset+0x77e/0x2cd0 drivers/net/usb/lan78xx.c:3241 lan78xx_bind+0x711/0x1690 drivers/net/usb/lan78xx.c:3766 The function lan78xx_read_raw_eeprom failed to properly propagate EEPROM read timeout errors (-ETIMEDOUT). In the fallthrough path, it first attempted to restore the pin configuration for LED outputs and then returned only the status of that restore operation, discarding the original timeout error. As a result, callers could mistakenly treat the data buffer as valid even though the EEPROM read had actually timed out with no data or partial data. To fix this, handle errors in restoring the LED pin configuration separately. If the restore succeeds, return any prior EEPROM timeout error correctly to the caller.
Affected ProductsAI
See vendor advisory for affected versions.
RemediationAI
No vendor patch is available at time of analysis. Monitor vendor advisories for updates. Apply vendor patches when available. Implement network segmentation and monitoring as interim mitigations.
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External POC / Exploit Code
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