In the Linux kernel, the following vulnerability has been resolved:

net: usb: lan78xx: Fix lost EEPROM read timeout error(-ETIMEDOUT) in lan78xxreadraw_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 lan78xxreadeeprom drivers/net/usb/lan78xx.c:1095 [inline] BUG: KMSAN: uninit-value in lan78xxinitmacaddress drivers/net/usb/lan78xx.c:1937 [inline] BUG: KMSAN: uninit-value in lan78xxreset+0x999/0x2cd0 drivers/net/usb/lan78xx.c:3241 lan78xxreadeeprom drivers/net/usb/lan78xx.c:1095 [inline] lan78xxinitmacaddress drivers/net/usb/lan78xx.c:1937 [inline] lan78xxreset+0x999/0x2cd0 drivers/net/usb/lan78xx.c:3241 lan78xxbind+0x711/0x1690 drivers/net/usb/lan78xx.c:3766 lan78xxprobe+0x225c/0x3310 drivers/net/usb/lan78xx.c:4707

Local variable sig.i.i created at: lan78xxreadeeprom drivers/net/usb/lan78xx.c:1092 [inline] lan78xxinitmacaddress drivers/net/usb/lan78xx.c:1937 [inline] lan78xxreset+0x77e/0x2cd0 drivers/net/usb/lan78xx.c:3241 lan78xx_bind+0x711/0x1690 drivers/net/usb/lan78xx.c:3766

The function lan78xxreadraw_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.