Commit-ID: 86cc35109029b7f1b195cef6c74654bad95e81af Gitweb: https://git.kernel.org/tip/86cc35109029b7f1b195cef6c74654bad95e81af Author: Ricardo Neri <ricardo.neri-calderon@xxxxxxxxxxxxxxx> AuthorDate: Sun, 5 Nov 2017 18:27:49 -0800 Committer: Ingo Molnar <mingo@xxxxxxxxxx> 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 <ricardo.neri-calderon@xxxxxxxxxxxxxxx> Reviewed-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Cc: Adam Buchbinder <adam.buchbinder@xxxxxxxxx> Cc: Adrian Hunter <adrian.hunter@xxxxxxxxx> Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> Cc: Andy Lutomirski <luto@xxxxxxxxxx> Cc: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx> Cc: Borislav Petkov <bp@xxxxxxxxx> Cc: Borislav Petkov <bp@xxxxxxx> Cc: Brian Gerst <brgerst@xxxxxxxxx> Cc: Chen Yucong <slaoub@xxxxxxxxx> Cc: Chris Metcalf <cmetcalf@xxxxxxxxxxxx> Cc: Colin Ian King <colin.king@xxxxxxxxxxxxx> Cc: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx> Cc: Denys Vlasenko <dvlasenk@xxxxxxxxxx> Cc: Dmitry Vyukov <dvyukov@xxxxxxxxxx> Cc: H. Peter Anvin <hpa@xxxxxxxxx> Cc: Huang Rui <ray.huang@xxxxxxx> Cc: Jiri Slaby <jslaby@xxxxxxx> Cc: Jonathan Corbet <corbet@xxxxxxx> Cc: Josh Poimboeuf <jpoimboe@xxxxxxxxxx> Cc: Kees Cook <keescook@xxxxxxxxxxxx> Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> Cc: Lorenzo Stoakes <lstoakes@xxxxxxxxx> Cc: Masami Hiramatsu <mhiramat@xxxxxxxxxx> Cc: Michael S. Tsirkin <mst@xxxxxxxxxx> Cc: Paolo Bonzini <pbonzini@xxxxxxxxxx> Cc: Paul Gortmaker <paul.gortmaker@xxxxxxxxxxxxx> Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx> Cc: Qiaowei Ren <qiaowei.ren@xxxxxxxxx> Cc: Ravi V. Shankar <ravi.v.shankar@xxxxxxxxx> Cc: Shuah Khan <shuah@xxxxxxxxxx> Cc: Thomas Garnier <thgarnie@xxxxxxxxxx> Cc: Tony Luck <tony.luck@xxxxxxxxx> Cc: Vlastimil Babka <vbabka@xxxxxxx> Cc: ricardo.neri@xxxxxxxxx Link: http://lkml.kernel.org/r/1509935277-22138-5-git-send-email-ricardo.neri-calderon@xxxxxxxxxxxxxxx Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx> --- 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; } -- To unsubscribe from this list: send the line "unsubscribe linux-tip-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
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