[tip: x86/misc] x86/insn-eval: Handle insn_get_opcode() failure

[tip-bot2 for Kirill A. Shutemov]

The following commit has been merged into the x86/misc branch of tip:

Commit-ID:     23ef731e4365196bfc186358eb4f6265d60ab352
Gitweb:        https://git.kernel.org/tip/23ef731e4365196bfc186358eb4f6265d60ab352
Author:        Kirill A. Shutemov <kirill@xxxxxxxxxxxxx>
AuthorDate:    Tue, 30 Nov 2021 21:49:30 +03:00
Committer:     Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
CommitterDate: Tue, 30 Nov 2021 14:52:26 -08:00

x86/insn-eval: Handle insn_get_opcode() failure

is_string_insn() calls insn_get_opcode() that can fail, but does not
handle the failure.

is_string_insn() interface does not allow to communicate an error to the
caller.

Push insn_get_opcode() to the only non-static user of is_string_insn()
and fail it early if insn_get_opcode() fails.

[ dhansen: fix tabs-versus-spaces breakage ]

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
Signed-off-by: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
Tested-by: Joerg Roedel <jroedel@xxxxxxx>
Acked-by: Tom Lendacky <thomas.lendacky@xxxxxxx>
Link: https://lkml.kernel.org/r/20211130184933.31005-2-kirill.shutemov@xxxxxxxxxxxxxxx
---
 arch/x86/lib/insn-eval.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/arch/x86/lib/insn-eval.c b/arch/x86/lib/insn-eval.c
index eb3ccff..1c51e8a 100644
--- a/arch/x86/lib/insn-eval.c
+++ b/arch/x86/lib/insn-eval.c
@@ -37,8 +37,6 @@ enum reg_type {
  */
 static bool is_string_insn(struct insn *insn)
 {
-	insn_get_opcode(insn);
-
 	/* All string instructions have a 1-byte opcode. */
 	if (insn->opcode.nbytes != 1)
 		return false;
@@ -1405,6 +1403,9 @@ void __user *insn_get_addr_ref(struct insn *insn, struct pt_regs *regs)
 	if (!insn || !regs)
 		return (void __user *)-1L;
 
+	if (insn_get_opcode(insn))
+		return (void __user *)-1L;
+
 	switch (insn->addr_bytes) {
 	case 2:
 		return get_addr_ref_16(insn, regs);