CVE-2021-47090

In the Linux kernel, the following vulnerability has been resolved:<br /> <br /> mm/hwpoison: clear MF_COUNT_INCREASED before retrying get_any_page()<br /> <br /> Hulk Robot reported a panic in put_page_testzero() when testing<br /> madvise() with MADV_SOFT_OFFLINE. The BUG() is triggered when retrying<br /> get_any_page(). This is because we keep MF_COUNT_INCREASED flag in<br /> second try but the refcnt is not increased.<br /> <br /> page dumped because: VM_BUG_ON_PAGE(page_ref_count(page) == 0)<br /> ------------[ cut here ]------------<br /> kernel BUG at include/linux/mm.h:737!<br /> invalid opcode: 0000 [#1] PREEMPT SMP<br /> CPU: 5 PID: 2135 Comm: sshd Tainted: G B 5.16.0-rc6-dirty #373<br /> Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.13.0-1ubuntu1.1 04/01/2014<br /> RIP: release_pages+0x53f/0x840<br /> Call Trace:<br /> free_pages_and_swap_cache+0x64/0x80<br /> tlb_flush_mmu+0x6f/0x220<br /> unmap_page_range+0xe6c/0x12c0<br /> unmap_single_vma+0x90/0x170<br /> unmap_vmas+0xc4/0x180<br /> exit_mmap+0xde/0x3a0<br /> mmput+0xa3/0x250<br /> do_exit+0x564/0x1470<br /> do_group_exit+0x3b/0x100<br /> __do_sys_exit_group+0x13/0x20<br /> __x64_sys_exit_group+0x16/0x20<br /> do_syscall_64+0x34/0x80<br /> entry_SYSCALL_64_after_hwframe+0x44/0xae<br /> Modules linked in:<br /> ---[ end trace e99579b570fe0649 ]---<br /> RIP: 0010:release_pages+0x53f/0x840