The following commit has been merged into the x86/urgent branch of tip: Commit-ID: 46a4ad7814fa39971aa6549b30c1a08d5c2ec65f Gitweb: https://git.kernel.org/tip/46a4ad7814fa39971aa6549b30c1a08d5c2ec65f Author: Masami Hiramatsu <mhiramat@xxxxxxxxxx> AuthorDate: Thu, 03 Dec 2020 13:51:01 +09:00 Committer: Borislav Petkov <bp@xxxxxxx> CommitterDate: Fri, 04 Dec 2020 14:45:15 +01:00 x86/sev-es: Use new for_each_insn_prefix() macro to loop over prefixes bytes 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@xxxxxxxxxxxx>. [ bp: Massage commit message. ] Fixes: 25189d08e516 ("x86/sev-es: Add support for handling IOIO exceptions") Reported-by: syzbot+9b64b619f10f19d19a7c@xxxxxxxxxxxxxxxxxxxxxxxxx Signed-off-by: Masami Hiramatsu <mhiramat@xxxxxxxxxx> Signed-off-by: Borislav Petkov <bp@xxxxxxx> Link: https://lkml.kernel.org/r/160697106089.3146288.2052422845039649176.stgit@devnote2 --- arch/x86/boot/compressed/sev-es.c | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-) diff --git a/arch/x86/boot/compressed/sev-es.c b/arch/x86/boot/compressed/sev-es.c index 954cb27..27826c2 100644 --- a/arch/x86/boot/compressed/sev-es.c +++ b/arch/x86/boot/compressed/sev-es.c @@ -32,13 +32,12 @@ struct ghcb *boot_ghcb; */ static bool insn_has_rep_prefix(struct insn *insn) { + insn_byte_t p; int i; insn_get_prefixes(insn); - for (i = 0; i < insn->prefixes.nbytes; i++) { - insn_byte_t p = insn->prefixes.bytes[i]; - + for_each_insn_prefix(insn, i, p) { if (p == 0xf2 || p == 0xf3) return true; }
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