CVE-2022-49004— riscv: Sync efi page table's kernel mappings before switching

riscv: Sync efi page table's kernel mappings before switching

In the Linux kernel, the following vulnerability has been resolved: riscv: Sync efi page table's kernel mappings before switching The EFI page table is initially created as a copy of the kernel page table. With VMAP_STACK enabled, kernel stacks are allocated in the vmalloc area: if the stack is allocated in a new PGD (one that was not present at the moment of the efi page table creation or not synced in a previous vmalloc fault), the kernel will take a trap when switching to the efi page table when the vmalloc kernel stack is accessed, resulting in a kernel panic. Fix that by updating the efi kernel mappings before switching to the efi page table.

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Linux kernel 安全漏洞

Linux kernel是美国Linux基金会的开源操作系统Linux所使用的内核。 Linux kernel存在安全漏洞，该漏洞源于EFI页面表的内核映射在切换到EFI页面表前未同步更新，可能导致访问vmalloc内核栈时触发陷阱并引起内核崩溃。

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