In the Linux kernel, the following vulnerability has been resolved: blk_iocost: fix more out of bound shifts Recently running UBSAN caught few out of bound shifts in the ioc_forgive_debts() function: UBSAN: shift-out-of-bounds in block/blk-iocost.c:2142:38 shift exponent 80 is too large for 64-bit type 'u64' (aka 'unsigned long long') ... UBSAN: shift-out-of-bounds in block/blk-iocost.c:2144:30 shift exponent 80 is too large for 64-bit type 'u64' (aka 'unsigned long long') ... Call Trace: <IRQ> dump_stack_lvl+0xca/0x130 __ubsan_handle_shift_out_of_bounds+0x22c/0x280 ? __lock_acquire+0x6441/0x7c10 ioc_timer_fn+0x6cec/0x7750 ? blk_iocost_init+0x720/0x720 ? call_timer_fn+0x5d/0x470 call_timer_fn+0xfa/0x470 ? blk_iocost_init+0x720/0x720 __run_timer_base+0x519/0x700 ... Actual impact of this issue was not identified but I propose to fix the undefined behaviour. The proposed fix to prevent those out of bound shifts consist of precalculating exponent before using it the shift operations by taking min value from the actual exponent and maximum possible number of bits.
https://git.kernel.org/stable/c/f4ef9bef023d5c543cb0f3194ecacfd47ef590ec
https://git.kernel.org/stable/c/9bce8005ec0dcb23a58300e8522fe4a31da606fa
https://git.kernel.org/stable/c/59121bb38fdc01434ea3fe361ee02b59f036227f
https://git.kernel.org/stable/c/364022095bdd4108efdaaa68576afa4712a5d085
https://git.kernel.org/stable/c/1f61d509257d6a05763d05bf37943b35306522b1
https://git.kernel.org/stable/c/1b120f151871eb47ce9f283c007af3f8ae1d990e
https://git.kernel.org/stable/c/1ab2cfe19700fb3dde4c7dfec392acff34db3120