[PATCH] m68k: use get_kernel_nofault in show_registers

[PATCH] m68k: use get_kernel_nofault in show_registers

[Christoph Hellwig]

Use the proper get_kernel_nofault helper to access an unsafe kernel
pointer without faulting instead of playing with set_fs and get_user.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 arch/m68k/kernel/traps.c | 5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)

diff --git a/arch/m68k/kernel/traps.c b/arch/m68k/kernel/traps.c
index df6fc782754f73..c265355fa244d4 100644
--- a/arch/m68k/kernel/traps.c
+++ b/arch/m68k/kernel/traps.c
@@ -846,7 +846,6 @@ static void show_trace(unsigned long *stack, const char *loglvl)
 void show_registers(struct pt_regs *regs)
 {
 	struct frame *fp = (struct frame *)regs;
-	mm_segment_t old_fs = get_fs();
 	u16 c, *cp;
 	unsigned long addr;
 	int i;
@@ -919,10 +918,9 @@ void show_registers(struct pt_regs *regs)
 	show_stack(NULL, (unsigned long *)addr, KERN_INFO);
 
 	pr_info("Code:");
-	set_fs(KERNEL_DS);
 	cp = (u16 *)regs->pc;
 	for (i = -8; i < 16; i++) {
-		if (get_user(c, cp + i) && i >= 0) {
+		if (get_kernel_nofault(c, cp + i) && i >= 0) {
 			pr_cont(" Bad PC value.");
 			break;
 		}
@@ -931,7 +929,6 @@ void show_registers(struct pt_regs *regs)
 		else
 			pr_cont(" <%04x>", c);
 	}
-	set_fs(old_fs);
 	pr_cont("\n");
 }
 
-- 
2.27.0

Re: [PATCH] m68k: use get_kernel_nofault in show_registers

[Geert Uytterhoeven]

On Mon, Jul 20, 2020 at 1:43 PM Christoph Hellwig <hch@lst.de> wrote:
> Use the proper get_kernel_nofault helper to access an unsafe kernel
> pointer without faulting instead of playing with set_fs and get_user.
>
> Signed-off-by: Christoph Hellwig <hch@lst.de>

Reviewed-by: Geert Uytterhoeven <geert@linux-m68k.org>
i.e. applied, and queued in the m68k for-v5.10 branch.

Gr{oetje,eeting}s,

                        Geert


--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds