Commit-ID: 86cc35109029b7f1b195cef6c74654bad95e81af Gitweb: https://git.kernel.org/tip/86cc35109029b7f1b195cef6c74654bad95e81af Author: Ricardo Neri <[email protected]> AuthorDate: Sun, 5 Nov 2017 18:27:49 -0800 Committer: Ingo Molnar <[email protected]> CommitDate: Wed, 8 Nov 2017 11:16:20 +0100
x86/insn-eval: Handle 32-bit address encodings in virtual-8086 mode It is possible to utilize 32-bit address encodings in virtual-8086 mode via an address override instruction prefix. However, the range of the effective address is still limited to [0x-0xffff]. In such a case, return error. Also, linear addresses in virtual-8086 mode are limited to 20 bits. Enforce such limit by truncating the most significant bytes of the computed linear address. Signed-off-by: Ricardo Neri <[email protected]> Reviewed-by: Thomas Gleixner <[email protected]> Cc: Adam Buchbinder <[email protected]> Cc: Adrian Hunter <[email protected]> Cc: Andrew Morton <[email protected]> Cc: Andy Lutomirski <[email protected]> Cc: Arnaldo Carvalho de Melo <[email protected]> Cc: Borislav Petkov <[email protected]> Cc: Borislav Petkov <[email protected]> Cc: Brian Gerst <[email protected]> Cc: Chen Yucong <[email protected]> Cc: Chris Metcalf <[email protected]> Cc: Colin Ian King <[email protected]> Cc: Dave Hansen <[email protected]> Cc: Denys Vlasenko <[email protected]> Cc: Dmitry Vyukov <[email protected]> Cc: H. Peter Anvin <[email protected]> Cc: Huang Rui <[email protected]> Cc: Jiri Slaby <[email protected]> Cc: Jonathan Corbet <[email protected]> Cc: Josh Poimboeuf <[email protected]> Cc: Kees Cook <[email protected]> Cc: Linus Torvalds <[email protected]> Cc: Lorenzo Stoakes <[email protected]> Cc: Masami Hiramatsu <[email protected]> Cc: Michael S. Tsirkin <[email protected]> Cc: Paolo Bonzini <[email protected]> Cc: Paul Gortmaker <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Qiaowei Ren <[email protected]> Cc: Ravi V. Shankar <[email protected]> Cc: Shuah Khan <[email protected]> Cc: Thomas Garnier <[email protected]> Cc: Tony Luck <[email protected]> Cc: Vlastimil Babka <[email protected]> Cc: [email protected] Link: http://lkml.kernel.org/r/1509935277-22138-5-git-send-email-ricardo.neri-calde...@linux.intel.com Signed-off-by: Ingo Molnar <[email protected]> --- arch/x86/lib/insn-eval.c | 11 +++++++++++ 1 file changed, 11 insertions(+) diff --git a/arch/x86/lib/insn-eval.c b/arch/x86/lib/insn-eval.c index 1ac3973..ef102db 100644 --- a/arch/x86/lib/insn-eval.c +++ b/arch/x86/lib/insn-eval.c @@ -1042,12 +1042,23 @@ static void __user *get_addr_ref_32(struct insn *insn, struct pt_regs *regs) goto out; /* + * Even though 32-bit address encodings are allowed in virtual-8086 + * mode, the address range is still limited to [0x-0xffff]. + */ + if (v8086_mode(regs) && (eff_addr & ~0xffff)) + goto out; + + /* * Data type long could be 64 bits in size. Ensure that our 32-bit * effective address is not sign-extended when computing the linear * address. */ linear_addr = (unsigned long)(eff_addr & 0xffffffff) + seg_base; + /* Limit linear address to 20 bits */ + if (v8086_mode(regs)) + linear_addr &= 0xfffff; + out: return (void __user *)linear_addr; }
