Messages in this thread Patch in this message | | | From | Masami Hiramatsu <> | Subject | [PATCH 2/3] x86/uprobes: Fix not using prefixes.nbytes for loop over prefixes.bytes | Date | Wed, 2 Dec 2020 17:51:16 +0900 |
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Since the insn.prefixes.nbytes can be bigger than the size of insn.prefixes.bytes[] when a same prefix is repeated, we have to check whether the insn.prefixes.bytes[i] != 0 and i < 4 instead of insn.prefixes.nbytes.
Fixes: 2b1444983508 ("uprobes, mm, x86: Add the ability to install and remove uprobes breakpoints") Cc: stable@vger.kernel.org Reported-by: Kees Cook <keescook@chromium.org> Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org> --- arch/x86/kernel/uprobes.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/arch/x86/kernel/uprobes.c b/arch/x86/kernel/uprobes.c index 3fdaa042823d..bb3ea3705b99 100644 --- a/arch/x86/kernel/uprobes.c +++ b/arch/x86/kernel/uprobes.c @@ -257,7 +257,7 @@ static bool is_prefix_bad(struct insn *insn) { int i; - for (i = 0; i < insn->prefixes.nbytes; i++) { + for (i = 0; insn->prefixes.bytes[i] && i < 4; i++) { insn_attr_t attr; attr = inat_get_opcode_attribute(insn->prefixes.bytes[i]); @@ -746,7 +746,7 @@ static int branch_setup_xol_ops(struct arch_uprobe *auprobe, struct insn *insn) * Intel and AMD behavior differ in 64-bit mode: Intel ignores 66 prefix. * No one uses these insns, reject any branch insns with such prefix. */ - for (i = 0; i < insn->prefixes.nbytes; i++) { + for (i = 0; insn->prefixes.bytes[i] && i < 4; i++) { if (insn->prefixes.bytes[i] == 0x66) return -ENOTSUPP; }
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