From: Masami Hiramatsu mhiramat@kernel.org
commit 12cb908a11b2544b5f53e9af856e6b6a90ed5533 upstream
Since insn.prefixes.nbytes can be bigger than the size of insn.prefixes.bytes[] when a prefix is repeated, the proper check must be
insn.prefixes.bytes[i] != 0 and i < 4
instead of using insn.prefixes.nbytes. Use the new for_each_insn_prefix() macro which does it correctly.
Debugged by Kees Cook keescook@chromium.org.
[ bp: Massage commit message. ]
Fixes: 32d0b95300db ("x86/insn-eval: Add utility functions to get segment selector") Reported-by: syzbot+9b64b619f10f19d19a7c@syzkaller.appspotmail.com Signed-off-by: Masami Hiramatsu mhiramat@kernel.org Signed-off-by: Borislav Petkov bp@suse.de Cc: stable@vger.kernel.org Link: https://lkml.kernel.org/r/160697104969.3146288.16329307586428270032.stgit@de... [sudip: adjust context] Signed-off-by: Sudip Mukherjee sudipm.mukherjee@gmail.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- arch/x86/lib/insn-eval.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-)
--- a/arch/x86/lib/insn-eval.c +++ b/arch/x86/lib/insn-eval.c @@ -70,14 +70,15 @@ static int get_seg_reg_override_idx(stru { int idx = INAT_SEG_REG_DEFAULT; int num_overrides = 0, i; + insn_byte_t p;
insn_get_prefixes(insn);
/* Look for any segment override prefixes. */ - for (i = 0; i < insn->prefixes.nbytes; i++) { + for_each_insn_prefix(insn, i, p) { insn_attr_t attr;
- attr = inat_get_opcode_attribute(insn->prefixes.bytes[i]); + attr = inat_get_opcode_attribute(p); switch (attr) { case INAT_MAKE_PREFIX(INAT_PFX_CS): idx = INAT_SEG_REG_CS;