x86 instructions cannot exceed 15 bytes, and the instruction
decoder should enforce that. Prior to 6ba48ff46f, the
instruction length limit was implicitly set to 16, which was an
approximation of 15, but there is currently no limit at all.
Fix MAX_INSN_SIZE (it should be 15, not 16), and fix the decoder
to reject instructions that exceed MAX_INSN_SIZE.
Other than potentially confusing some of the decoder sanity
checks, I'm not aware of any actual problems that omitting this
check would cause, nor am I aware of any practical problems
caused by the MAX_INSN_SIZE error.
Signed-off-by: Andy Lutomirski <luto@amacapital.net>
Acked-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Fixes: 6ba48ff46f ("x86: Remove arbitrary instruction size limit ...
Link: http://lkml.kernel.org/r/f8f0bc9b8c58cfd6830f7d88400bf1396cbdcd0f.1422403511.git.luto@amacapital.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Stephane reported that the PEBS fixup was broken by the recent commit to
the instruction decoder. The thing had an off-by-one which resulted in
not being able to decode the last instruction and always bail.
Reported-by: Stephane Eranian <eranian@google.com>
Fixes: 6ba48ff46f ("x86: Remove arbitrary instruction size limit in instruction decoder")
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: stable@vger.kernel.org # 3.18
Cc: <ak@linux.intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Liang Kan <kan.liang@intel.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Jim Keniston <jkenisto@us.ibm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Link: http://lkml.kernel.org/r/20141216104614.GV3337@twins.programming.kicks-ass.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The current x86 instruction decoder steps along through the
instruction stream but always ensures that it never steps farther
than the largest possible instruction size (MAX_INSN_SIZE).
The MPX code is now going to be doing some decoding of userspace
instructions. We copy those from userspace in to the kernel and
they're obviously completely untrusted coming from userspace. In
addition to the constraint that instructions can only be so long,
we also have to be aware of how long the buffer is that came in
from userspace. This _looks_ to be similar to what the perf and
kprobes is doing, but it's unclear to me whether they are
affected.
The whole reason we need this is that it is perfectly valid to be
executing an instruction within MAX_INSN_SIZE bytes of an
unreadable page. We should be able to gracefully handle short
reads in those cases.
This adds support to the decoder to record how long the buffer
being decoded is and to refuse to "validate" the instruction if
we would have gone over the end of the buffer to decode it.
The kprobes code probably needs to be looked at here a bit more
carefully. This patch still respects the MAX_INSN_SIZE limit
there but the kprobes code does look like it might be able to
be a bit more strict than it currently is.
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Acked-by: Jim Keniston <jkenisto@us.ibm.com>
Acked-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: x86@kernel.org
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Cc: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>
Cc: "David S. Miller" <davem@davemloft.net>
Link: http://lkml.kernel.org/r/20141114153957.E6B01535@viggo.jf.intel.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Fix a build failure in the x86 insn_sanity program after the UAPI split. The
problem is that insn_sanity.c #includes arch/x86/lib/insn.c - which uses the
kernel string header. This leads to conflicts for various definitions against
the /usr/include/ headers.
linux/string.h can be replaced with the normal userspace string.h if __KERNEL__
is not specified.
HOSTCC arch/x86/tools/insn_sanity
In file included from /data/fs/linux-2.6-hdr/include/linux/string.h:6:0,
from /data/fs/linux-2.6-hdr/arch/x86/lib/insn.c:21,
from arch/x86/tools/insn_sanity.c:36:
/data/fs/linux-2.6-hdr/include/linux/types.h:14:26: error: conflicting types for 'fd_set'
/usr/include/sys/select.h:76:5: note: previous declaration of 'fd_set' was here
/data/fs/linux-2.6-hdr/include/linux/types.h:15:25: error: conflicting types for 'dev_t'
/usr/include/sys/types.h:61:17: note: previous declaration of 'dev_t' was here
/data/fs/linux-2.6-hdr/include/linux/types.h:25:26: error: conflicting types for 'timer_t'
/usr/include/time.h:104:19: note: previous declaration of 'timer_t' was here
/data/fs/linux-2.6-hdr/include/linux/types.h:45:26: error: conflicting types for 'loff_t'
/usr/include/sys/types.h:45:18: note: previous declaration of 'loff_t' was here
/data/fs/linux-2.6-hdr/include/linux/types.h:112:17: error: conflicting types for 'u_int64_t'
/usr/include/sys/types.h:204:1: note: previous declaration of 'u_int64_t' was here
/data/fs/linux-2.6-hdr/include/linux/types.h:113:17: error: conflicting types for 'int64_t'
/usr/include/sys/types.h:198:1: note: previous declaration of 'int64_t' was here
/data/fs/linux-2.6-hdr/include/linux/types.h:134:23: error: conflicting types for 'blkcnt_t'
/usr/include/sys/types.h:236:20: note: previous declaration of 'blkcnt_t' was here
In file included from /data/fs/linux-2.6-hdr/arch/x86/lib/insn.c:21:0,
from arch/x86/tools/insn_sanity.c:36:
/data/fs/linux-2.6-hdr/include/linux/string.h:38:12: error: expected identifier or '(' before '__extension__'
/data/fs/linux-2.6-hdr/include/linux/string.h:38:12: error: expected identifier or '(' before ')' token
/data/fs/linux-2.6-hdr/include/linux/string.h:41:12: error: expected identifier or '(' before '__extension__'
/data/fs/linux-2.6-hdr/include/linux/string.h:53:15: error: expected identifier or '(' before '__extension__'
/data/fs/linux-2.6-hdr/include/linux/string.h:61:28: error: expected '=', ',', ';', 'asm' or '__attribute__' before 'skip_spaces'
/data/fs/linux-2.6-hdr/include/linux/string.h:65:28: error: expected '=', ',', ';', 'asm' or '__attribute__' before 'char'
/data/fs/linux-2.6-hdr/include/linux/string.h:83:15: error: expected identifier or '(' before '__extension__'
/data/fs/linux-2.6-hdr/include/linux/string.h:83:15: error: expected identifier or '(' before ')' token
/data/fs/linux-2.6-hdr/include/linux/string.h:86:15: error: expected identifier or '(' before '__extension__'
/data/fs/linux-2.6-hdr/include/linux/string.h:86:15: error: expected identifier or '(' before ')' token
/data/fs/linux-2.6-hdr/include/linux/string.h:89:24: error: expected identifier or '(' before '__extension__'
/data/fs/linux-2.6-hdr/include/linux/string.h:89:24: error: expected identifier or '(' before ')' token
/data/fs/linux-2.6-hdr/include/linux/string.h:92:24: error: expected identifier or '(' before '__extension__'
/data/fs/linux-2.6-hdr/include/linux/string.h:92:24: error: expected identifier or '(' before ')' token
Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Acked-by: Dave Jones <davej@redhat.com>
This can happen if the instruction is much longer than the maximum length,
or if insn->opnd_bytes is manually changed.
This patch also fixes warnings from -Wswitch-default flag.
Reported-by: Prashanth Nageshappa <prashanth@linux.vnet.ibm.com>
Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Cc: Jim Keniston <jkenisto@linux.vnet.ibm.com>
Cc: Linux-mm <linux-mm@kvack.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Arnaldo Carvalho de Melo <acme@infradead.org>
Cc: Anton Arapov <anton@redhat.com>
Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Cc: yrl.pp-manager.tt@hitachi.com
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20120413032427.32577.42602.stgit@localhost.localdomain
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Fix to decode grouped AVX with VEX pp bits which should be
handled as same as last-prefixes. This fixes below warnings
in posttest with CONFIG_CRYPTO_SHA1_SSSE3=y.
Warning: arch/x86/tools/test_get_len found difference at <sha1_transform_avx>:ffffffff810d5fc0
Warning: ffffffff810d6069: c5 f9 73 de 04 vpsrldq $0x4,%xmm6,%xmm0
Warning: objdump says 5 bytes, but insn_get_length() says 4
...
With this change, test_get_len can decode it correctly.
$ arch/x86/tools/test_get_len -v -y
ffffffff810d6069: c5 f9 73 de 04 vpsrldq $0x4,%xmm6,%xmm0
Succeed: decoded and checked 1 instructions
Reported-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: yrl.pp-manager.tt@hitachi.com
Link: http://lkml.kernel.org/r/20120210053340.30429.73410.stgit@localhost.localdomain
Signed-off-by: Ingo Molnar <mingo@elte.hu>
For reducing memory usage of attribute table, x86 instruction
decoder puts "Group" attribute only on "no-last-prefix"
attribute table (same as vex_p == 0 case).
Thus, the decoder should look no-last-prefix table first, and
then only if it is not a group, move on to "with-last-prefix"
table (vex_p != 0).
However, current implementation, inat_get_avx_attribute()
looks with-last-prefix directly. So, when decoding
a grouped AVX instruction, the decoder fails to find correct
group because there is no "Group" attribute on the table.
This ends up with the mis-decoding of instructions, as Ingo
reported in http://thread.gmane.org/gmane.linux.kernel/1214103
This patch fixes it to check no-last-prefix table first
even if that is an AVX instruction, and get an attribute from
"with last-prefix" table only if that is not a group.
Reported-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: yrl.pp-manager.tt@hitachi.com
Link: http://lkml.kernel.org/r/20111205120539.15475.91428.stgit@cloud
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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>
Add Intel AVX(Advanced Vector Extensions) instruction set
support to x86 instruction decoder. This adds insn.vex_prefix
field for storing VEX prefixes, and introduces some original
tags for expressing opcodes attributes.
Signed-off-by: Masami Hiramatsu <mhiramat@redhat.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Jim Keniston <jkenisto@us.ibm.com>
Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Frank Ch. Eigler <fche@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Jason Baron <jbaron@redhat.com>
Cc: K.Prasad <prasad@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
LKML-Reference: <20091027204226.30545.23451.stgit@harusame>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Add x86 instruction decoder to arch-specific libraries. This decoder
can decode x86 instructions used in kernel into prefix, opcode, modrm,
sib, displacement and immediates. This can also show the length of
instructions.
This version introduces instruction attributes for decoding
instructions.
The instruction attribute tables are generated from the opcode map file
(x86-opcode-map.txt) by the generator script(gen-insn-attr-x86.awk).
Currently, the opcode maps are based on opcode maps in Intel(R) 64 and
IA-32 Architectures Software Developers Manual Vol.2: Appendix.A,
and consist of below two types of opcode tables.
1-byte/2-bytes/3-bytes opcodes, which has 256 elements, are
written as below;
Table: table-name
Referrer: escaped-name
opcode: mnemonic|GrpXXX [operand1[,operand2...]] [(extra1)[,(extra2)...] [| 2nd-mnemonic ...]
(or)
opcode: escape # escaped-name
EndTable
Group opcodes, which has 8 elements, are written as below;
GrpTable: GrpXXX
reg: mnemonic [operand1[,operand2...]] [(extra1)[,(extra2)...] [| 2nd-mnemonic ...]
EndTable
These opcode maps include a few SSE and FP opcodes (for setup), because
those opcodes are used in the kernel.
Signed-off-by: Masami Hiramatsu <mhiramat@redhat.com>
Signed-off-by: Jim Keniston <jkenisto@us.ibm.com>
Acked-by: H. Peter Anvin <hpa@zytor.com>
Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Cc: Avi Kivity <avi@redhat.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Frank Ch. Eigler <fche@redhat.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Jason Baron <jbaron@redhat.com>
Cc: K.Prasad <prasad@linux.vnet.ibm.com>
Cc: Lai Jiangshan <laijs@cn.fujitsu.com>
Cc: Li Zefan <lizf@cn.fujitsu.com>
Cc: Przemysław Pawełczyk <przemyslaw@pawelczyk.it>
Cc: Roland McGrath <roland@redhat.com>
Cc: Sam Ravnborg <sam@ravnborg.org>
Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Tom Zanussi <tzanussi@gmail.com>
Cc: Vegard Nossum <vegard.nossum@gmail.com>
LKML-Reference: <20090813203413.31965.49709.stgit@localhost.localdomain>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Andy Lutomirski