Commit b8d2eff3 authored Oct 27, 2017 by Ricardo Neri Committed by Thomas Gleixner Nov 01, 2017

x86/mpx: Use signed variables to compute effective addresses



Even though memory addresses are unsigned, the operands used to compute the
effective address do have a sign. This is true for ModRM.rm, SIB.base,
SIB.index as well as the displacement bytes. Thus, signed variables shall
be used when computing the effective address from these operands. Once the
signed effective address has been computed, it is casted to an unsigned
long to determine the linear address.

Variables are renamed to better reflect the type of address being
computed.

Signed-off-by: Ricardo Neri <ricardo.neri-calderon@linux.intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Borislav Petkov <bp@suse.de>
Cc: Adan Hawthorn <adanhawthorn@gmail.com>
Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: ricardo.neri@intel.com
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: Huang Rui <ray.huang@amd.com>
Cc: Qiaowei Ren <qiaowei.ren@intel.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Jiri Slaby <jslaby@suse.cz>
Cc: Nathan Howard <liverlint@gmail.com>
Cc: "Ravi V. Shankar" <ravi.v.shankar@intel.com>
Cc: Chris Metcalf <cmetcalf@mellanox.com>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Colin Ian King <colin.king@canonical.com>
Cc: Chen Yucong <slaoub@gmail.com>
Cc: Adam Buchbinder <adam.buchbinder@gmail.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Lorenzo Stoakes <lstoakes@gmail.com>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Joe Perches <joe@perches.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Link: https://lkml.kernel.org/r/1509135945-13762-7-git-send-email-ricardo.neri-calderon@linux.intel.com

parent b15d70df

arch/x86/mm/mpx.c

+14 −6

Original line number	Diff line number	Diff line
		@@ -138,8 +138,9 @@ static int get_reg_offset(struct insn insn, struct pt_regs regs,
		*/
		static void __user mpx_get_addr_ref(struct insn insn, struct pt_regs *regs)
		{
		unsigned long addr = -1L, base, indx;
		int addr_offset, base_offset, indx_offset;
		unsigned long linear_addr = -1L;
		long eff_addr, base, indx;
		insn_byte_t sib;

		insn_get_modrm(insn);
		@@ -150,7 +151,8 @@ static void __user mpx_get_addr_ref(struct insn insn, struct pt_regs *regs)
		addr_offset = get_reg_offset(insn, regs, REG_TYPE_RM);
		if (addr_offset < 0)
		goto out;
		addr = regs_get_register(regs, addr_offset);

		eff_addr = regs_get_register(regs, addr_offset);
		} else {
		if (insn->sib.nbytes) {
		base_offset = get_reg_offset(insn, regs, REG_TYPE_BASE);
		@@ -163,17 +165,23 @@ static void __user mpx_get_addr_ref(struct insn insn, struct pt_regs *regs)

		base = regs_get_register(regs, base_offset);
		indx = regs_get_register(regs, indx_offset);
		addr = base + indx * (1 << X86_SIB_SCALE(sib));

		eff_addr = base + indx * (1 << X86_SIB_SCALE(sib));
		} else {
		addr_offset = get_reg_offset(insn, regs, REG_TYPE_RM);
		if (addr_offset < 0)
		goto out;
		addr = regs_get_register(regs, addr_offset);

		eff_addr = regs_get_register(regs, addr_offset);
		}
		addr += insn->displacement.value;

		eff_addr += insn->displacement.value;
		}

		linear_addr = (unsigned long)eff_addr;

		out:
		return (void __user *)addr;
		return (void __user *)linear_addr;
		}

		static int mpx_insn_decode(struct insn *insn,

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