CVE-2023-53783

In the Linux kernel, the following vulnerability has been resolved:<br /> <br /> blk-iocost: fix divide by 0 error in calc_lcoefs()<br /> <br /> echo max of u64 to cost.model can cause divide by 0 error.<br /> <br /> # echo 8:0 rbps=18446744073709551615 &gt; /sys/fs/cgroup/io.cost.model<br /> <br /> divide error: 0000 [#1] PREEMPT SMP<br /> RIP: 0010:calc_lcoefs+0x4c/0xc0<br /> Call Trace:<br /> <br /> ioc_refresh_params+0x2b3/0x4f0<br /> ioc_cost_model_write+0x3cb/0x4c0<br /> ? _copy_from_iter+0x6d/0x6c0<br /> ? kernfs_fop_write_iter+0xfc/0x270<br /> cgroup_file_write+0xa0/0x200<br /> kernfs_fop_write_iter+0x17d/0x270<br /> vfs_write+0x414/0x620<br /> ksys_write+0x73/0x160<br /> __x64_sys_write+0x1e/0x30<br /> do_syscall_64+0x35/0x80<br /> entry_SYSCALL_64_after_hwframe+0x63/0xcd<br /> <br /> calc_lcoefs() uses the input value of cost.model in DIV_ROUND_UP_ULL,<br /> overflow would happen if bps plus IOC_PAGE_SIZE is greater than<br /> ULLONG_MAX, it can cause divide by 0 error.<br /> <br /> Fix the problem by setting basecost