CVE-2022-49623

In the Linux kernel, the following vulnerability has been resolved:<br /> <br /> powerpc/xive/spapr: correct bitmap allocation size<br /> <br /> kasan detects access beyond the end of the xibm-&gt;bitmap allocation:<br /> <br /> BUG: KASAN: slab-out-of-bounds in _find_first_zero_bit+0x40/0x140<br /> Read of size 8 at addr c00000001d1d0118 by task swapper/0/1<br /> <br /> CPU: 0 PID: 1 Comm: swapper/0 Not tainted 5.19.0-rc2-00001-g90df023b36dd #28<br /> Call Trace:<br /> [c00000001d98f770] [c0000000012baab8] dump_stack_lvl+0xac/0x108 (unreliable)<br /> [c00000001d98f7b0] [c00000000068faac] print_report+0x37c/0x710<br /> [c00000001d98f880] [c0000000006902c0] kasan_report+0x110/0x354<br /> [c00000001d98f950] [c000000000692324] __asan_load8+0xa4/0xe0<br /> [c00000001d98f970] [c0000000011c6ed0] _find_first_zero_bit+0x40/0x140<br /> [c00000001d98f9b0] [c0000000000dbfbc] xive_spapr_get_ipi+0xcc/0x260<br /> [c00000001d98fa70] [c0000000000d6d28] xive_setup_cpu_ipi+0x1e8/0x450<br /> [c00000001d98fb30] [c000000004032a20] pSeries_smp_probe+0x5c/0x118<br /> [c00000001d98fb60] [c000000004018b44] smp_prepare_cpus+0x944/0x9ac<br /> [c00000001d98fc90] [c000000004009f9c] kernel_init_freeable+0x2d4/0x640<br /> [c00000001d98fd90] [c0000000000131e8] kernel_init+0x28/0x1d0<br /> [c00000001d98fe10] [c00000000000cd54] ret_from_kernel_thread+0x5c/0x64<br /> <br /> Allocated by task 0:<br /> kasan_save_stack+0x34/0x70<br /> __kasan_kmalloc+0xb4/0xf0<br /> __kmalloc+0x268/0x540<br /> xive_spapr_init+0x4d0/0x77c<br /> pseries_init_irq+0x40/0x27c<br /> init_IRQ+0x44/0x84<br /> start_kernel+0x2a4/0x538<br /> start_here_common+0x1c/0x20<br /> <br /> The buggy address belongs to the object at c00000001d1d0118<br /> which belongs to the cache kmalloc-8 of size 8<br /> The buggy address is located 0 bytes inside of<br /> 8-byte region [c00000001d1d0118, c00000001d1d0120)<br /> <br /> The buggy address belongs to the physical page:<br /> page:c00c000000074740 refcount:1 mapcount:0 mapping:0000000000000000 index:0xc00000001d1d0558 pfn:0x1d1d<br /> flags: 0x7ffff000000200(slab|node=0|zone=0|lastcpupid=0x7ffff)<br /> raw: 007ffff000000200 c00000001d0003c8 c00000001d0003c8 c00000001d010480<br /> raw: c00000001d1d0558 0000000001e1000a 00000001ffffffff 0000000000000000<br /> page dumped because: kasan: bad access detected<br /> <br /> Memory state around the buggy address:<br /> c00000001d1d0000: fc 00 fc fc fc fc fc fc fc fc fc fc fc fc fc fc<br /> c00000001d1d0080: fc fc 00 fc fc fc fc fc fc fc fc fc fc fc fc fc<br /> &gt;c00000001d1d0100: fc fc fc 02 fc fc fc fc fc fc fc fc fc fc fc fc<br /> ^<br /> c00000001d1d0180: fc fc fc fc 04 fc fc fc fc fc fc fc fc fc fc fc<br /> c00000001d1d0200: fc fc fc fc fc 04 fc fc fc fc fc fc fc fc fc fc<br /> <br /> This happens because the allocation uses the wrong unit (bits) when it<br /> should pass (BITS_TO_LONGS(count) * sizeof(long)) or equivalent. With small<br /> numbers of bits, the allocated object can be smaller than sizeof(long),<br /> which results in invalid accesses.<br /> <br /> Use bitmap_zalloc() to allocate and initialize the irq bitmap, paired with<br /> bitmap_free() for consistency.