[PATCH] ARM: kprobes: Fix false positive with FORTIFY_SOURCE
From: mhiramat@kernel.org (Masami Hiramatsu)
Date: 2018-10-23 01:06:10
Also in:
lkml
On Mon, 22 Oct 2018 02:30:23 -0700 Kees Cook [off-list ref] wrote:
The arm compiler internally interprets an inline assembly label
as an unsigned long value, not a pointer. As a result, under
CONFIG_FORTIFY_SOURCE, the size of the array pointed to by an address
of a label is 4 bytes, which was tripping the runtime checks. Instead,
we can just cast the label (as done with the size calculations earlier)
to avoid the problem.
Reported-by: William Cohen <redacted>
Fixes: 6974f0c4555e ("include/linux/string.h: add the option of fortified string.h functions")
Cc: stable at vger.kernel.org
Signed-off-by: Kees Cook <redacted>Good catch! This looks good to me. Acked-by: Masami Hiramatsu <mhiramat@kernel.org> Thank you,
quoted hunk ↗ jump to hunk
--- arch/arm/probes/kprobes/opt-arm.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)diff --git a/arch/arm/probes/kprobes/opt-arm.c b/arch/arm/probes/kprobes/opt-arm.c index b2aa9b32bff2..2c118a6ab358 100644 --- a/arch/arm/probes/kprobes/opt-arm.c +++ b/arch/arm/probes/kprobes/opt-arm.c@@ -247,7 +247,7 @@ int arch_prepare_optimized_kprobe(struct optimized_kprobe *op, struct kprobe *or } /* Copy arch-dep-instance from template. */ - memcpy(code, &optprobe_template_entry, + memcpy(code, (unsigned char *)optprobe_template_entry, TMPL_END_IDX * sizeof(kprobe_opcode_t)); /* Adjust buffer according to instruction. */-- 2.17.1 -- Kees Cook Pixel Security
-- Masami Hiramatsu [off-list ref]