In the Linux kernel, the following vulnerability has been resolved:
workqueue: Fix UBSAN 'subtraction overflow' error in shiftandmask()
UBSAN reports the following 'subtraction overflow' error when booting in a virtual machine on Android:
| Internal error: UBSAN: integer subtraction overflow: 00000000f2005515 [#1] PREEMPT SMP | Modules linked in: | CPU: 0 PID: 1 Comm: swapper/0 Not tainted 6.10.0-00006-g3cbe9e5abd46-dirty #4 | Hardware name: linux,dummy-virt (DT) | pstate: 600000c5 (nZCv daIF -PAN -UAO -TCO -DIT -SSBS BTYPE=--) | pc : canceldelayedwork+0x34/0x44 | lr : canceldelayedwork+0x2c/0x44 | sp : ffff80008002ba60 | x29: ffff80008002ba60 x28: 0000000000000000 x27: 0000000000000000 | x26: 0000000000000000 x25: 0000000000000000 x24: 0000000000000000 | x23: 0000000000000000 x22: 0000000000000000 x21: ffff1f65014cd3c0 | x20: ffffc0e84c9d0da0 x19: ffffc0e84cab3558 x18: ffff800080009058 | x17: 00000000247ee1f8 x16: 00000000247ee1f8 x15: 00000000bdcb279d | x14: 0000000000000001 x13: 0000000000000075 x12: 00000a0000000000 | x11: ffff1f6501499018 x10: 00984901651fffff x9 : ffff5e7cc35af000 | x8 : 0000000000000001 x7 : 3d4d455453595342 x6 : 000000004e514553 | x5 : ffff1f6501499265 x4 : ffff1f650ff60b10 x3 : 0000000000000620 | x2 : ffff80008002ba78 x1 : 0000000000000000 x0 : 0000000000000000 | Call trace: | canceldelayedwork+0x34/0x44 | deferredprobeextendtimeout+0x20/0x70 | driverregister+0xa8/0x110 | _platformdriverregister+0x28/0x3c | sysconinit+0x24/0x38 | dooneinitcall+0xe4/0x338 | doinitcalllevel+0xac/0x178 | doinitcalls+0x5c/0xa0 | dobasicsetup+0x20/0x30 | kernelinitfreeable+0x8c/0xf8 | kernelinit+0x28/0x1b4 | retfromfork+0x10/0x20 | Code: f9000fbf 97fffa2f 39400268 37100048 (d42aa2a0) | ---[ end trace 0000000000000000 ]--- | Kernel panic - not syncing: UBSAN: integer subtraction overflow: Fatal exception
This is due to shiftandmask() using a signed immediate to construct the mask and being called with a shift of 31 (WORKOFFQPOOLSHIFT) so that it ends up decrementing from INTMIN.
Use an unsigned constant '1U' to generate the mask in shiftandmask().