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authorMasami Hiramatsu <masami.hiramatsu.pt@hitachi.com>2011-10-07 22:31:55 +0900
committerIngo Molnar <mingo@elte.hu>2011-10-10 09:05:51 +0200
commit53a019a951fae849471e4a620948c5f6886bd1a4 (patch)
tree3c37f0297b628e263f74f146352f39cd5401134a /arch/x86
parent65112dccf8a113737684366349d7f9ec373ddc47 (diff)
downloadlinux-53a019a951fae849471e4a620948c5f6886bd1a4.tar.bz2
x86: Fix insn decoder for longer instruction
Fix x86 insn decoder for hardening against invalid length instructions. This adds length checkings for each byte-read site and if it exceeds MAX_INSN_SIZE, returns immediately. This can happen when decoding user-space binary. Caller can check whether it happened by checking insn.*.got member is set or not. Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Cc: Stephane Eranian <eranian@google.com> Cc: Andi Kleen <andi@firstfloor.org> Cc: acme@redhat.com Cc: ming.m.lin@intel.com Cc: robert.richter@amd.com Cc: ravitillo@lbl.gov Cc: yrl.pp-manager.tt@hitachi.com Cc: Peter Zijlstra <peterz@infradead.org> Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com> Cc: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/20111007133155.10933.58577.stgit@localhost.localdomain Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'arch/x86')
-rw-r--r--arch/x86/lib/insn.c48
1 files changed, 43 insertions, 5 deletions
diff --git a/arch/x86/lib/insn.c b/arch/x86/lib/insn.c
index 9f33b984d0ef..374562ed6704 100644
--- a/arch/x86/lib/insn.c
+++ b/arch/x86/lib/insn.c
@@ -22,14 +22,23 @@
#include <asm/inat.h>
#include <asm/insn.h>
-#define get_next(t, insn) \
- ({t r; r = *(t*)insn->next_byte; insn->next_byte += sizeof(t); r; })
+/* Verify next sizeof(t) bytes can be on the same instruction */
+#define validate_next(t, insn, n) \
+ ((insn)->next_byte + sizeof(t) + n - (insn)->kaddr <= MAX_INSN_SIZE)
+
+#define __get_next(t, insn) \
+ ({ t r = *(t*)insn->next_byte; insn->next_byte += sizeof(t); r; })
+
+#define __peek_nbyte_next(t, insn, n) \
+ ({ t r = *(t*)((insn)->next_byte + n); r; })
-#define peek_next(t, insn) \
- ({t r; r = *(t*)insn->next_byte; r; })
+#define get_next(t, insn) \
+ ({ if (unlikely(!validate_next(t, insn, 0))) goto err_out; __get_next(t, insn); })
#define peek_nbyte_next(t, insn, n) \
- ({t r; r = *(t*)((insn)->next_byte + n); r; })
+ ({ if (unlikely(!validate_next(t, insn, n))) goto err_out; __peek_nbyte_next(t, insn, n); })
+
+#define peek_next(t, insn) peek_nbyte_next(t, insn, 0)
/**
* insn_init() - initialize struct insn
@@ -158,6 +167,8 @@ vex_end:
insn->vex_prefix.got = 1;
prefixes->got = 1;
+
+err_out:
return;
}
@@ -208,6 +219,9 @@ void insn_get_opcode(struct insn *insn)
insn->attr = 0; /* This instruction is bad */
end:
opcode->got = 1;
+
+err_out:
+ return;
}
/**
@@ -241,6 +255,9 @@ void insn_get_modrm(struct insn *insn)
if (insn->x86_64 && inat_is_force64(insn->attr))
insn->opnd_bytes = 8;
modrm->got = 1;
+
+err_out:
+ return;
}
@@ -290,6 +307,9 @@ void insn_get_sib(struct insn *insn)
}
}
insn->sib.got = 1;
+
+err_out:
+ return;
}
@@ -351,6 +371,9 @@ void insn_get_displacement(struct insn *insn)
}
out:
insn->displacement.got = 1;
+
+err_out:
+ return;
}
/* Decode moffset16/32/64 */
@@ -373,6 +396,9 @@ static void __get_moffset(struct insn *insn)
break;
}
insn->moffset1.got = insn->moffset2.got = 1;
+
+err_out:
+ return;
}
/* Decode imm v32(Iz) */
@@ -389,6 +415,9 @@ static void __get_immv32(struct insn *insn)
insn->immediate.nbytes = 4;
break;
}
+
+err_out:
+ return;
}
/* Decode imm v64(Iv/Ov) */
@@ -411,6 +440,9 @@ static void __get_immv(struct insn *insn)
break;
}
insn->immediate1.got = insn->immediate2.got = 1;
+
+err_out:
+ return;
}
/* Decode ptr16:16/32(Ap) */
@@ -432,6 +464,9 @@ static void __get_immptr(struct insn *insn)
insn->immediate2.value = get_next(unsigned short, insn);
insn->immediate2.nbytes = 2;
insn->immediate1.got = insn->immediate2.got = 1;
+
+err_out:
+ return;
}
/**
@@ -496,6 +531,9 @@ void insn_get_immediate(struct insn *insn)
}
done:
insn->immediate.got = 1;
+
+err_out:
+ return;
}
/**