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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 <ricardo.neri-calderon@linux.intel.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Adam Buchbinder <adam.buchbinder@gmail.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Borislav Petkov <bp@suse.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Chen Yucong <slaoub@gmail.com>
Cc: Chris Metcalf <cmetcalf@mellanox.com>
Cc: Colin Ian King <colin.king@canonical.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Huang Rui <ray.huang@amd.com>
Cc: Jiri Slaby <jslaby@suse.cz>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Lorenzo Stoakes <lstoakes@gmail.com>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Michael S. Tsirkin <mst@redhat.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Qiaowei Ren <qiaowei.ren@intel.com>
Cc: Ravi V. Shankar <ravi.v.shankar@intel.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Thomas Garnier <thgarnie@google.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: ricardo.neri@intel.com
Link: http://lkml.kernel.org/r/1509935277-22138-5-git-send-email-ricardo.neri-calderon@linux.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Ricardo Neri 2017-11-05 18:27:49 -08:00 committed by Ingo Molnar
parent cd9b594a9e
commit 86cc351090
1 changed files with 11 additions and 0 deletions
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11
arch/x86/lib/insn-eval.c
View File

@ -1041,6 +1041,13 @@ static void __user *get_addr_ref_32(struct insn *insn, struct pt_regs *regs)
if (!user_64bit_mode(regs) && ((unsigned int)eff_addr > seg_limit))
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
@ -1048,6 +1055,10 @@ static void __user *get_addr_ref_32(struct insn *insn, struct pt_regs *regs)
*/
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;
}