From fa2f478a348efa483abd4159c9f5478a3867bcc0 Mon Sep 17 00:00:00 2001
From: Christoph Hellwig <hch@lst.de>
Date: Mon, 20 Jul 2020 13:44:48 +0200
Subject: [PATCH] nds32: use get_kernel_nofault in dump_mem
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>
Acked-by: Nick Hu <nickhu@andestech.com>
Acked-by: Greentime Hu <green.hu@gmail.com>
Signed-off-by: Greentime Hu <green.hu@gmail.com>
---
arch/nds32/kernel/traps.c | 15 +++------------
1 file changed, 3 insertions(+), 12 deletions(-)
diff --git a/arch/nds32/kernel/traps.c b/arch/nds32/kernel/traps.c
index b66f889bc6df9..ee0d9ae192a50 100644
--- a/arch/nds32/kernel/traps.c
+++ b/arch/nds32/kernel/traps.c
@@ -25,17 +25,8 @@ extern void show_pte(struct mm_struct *mm, unsigned long addr);
void dump_mem(const char *lvl, unsigned long bottom, unsigned long top)
{
unsigned long first;
- mm_segment_t fs;
int i;
- /*
- * We need to switch to kernel mode so that we can use __get_user
- * to safely read from kernel space. Note that we now dump the
- * code first, just in case the backtrace kills us.
- */
- fs = get_fs();
- set_fs(KERNEL_DS);
-
pr_emerg("%s(0x%08lx to 0x%08lx)\n", lvl, bottom, top);
for (first = bottom & ~31; first < top; first += 32) {
@@ -48,7 +39,9 @@ void dump_mem(const char *lvl, unsigned long bottom, unsigned long top)
for (p = first, i = 0; i < 8 && p < top; i++, p += 4) {
if (p >= bottom && p < top) {
unsigned long val;
- if (__get_user(val, (unsigned long *)p) == 0)
+
+ if (get_kernel_nofault(val,
+ (unsigned long *)p) == 0)
sprintf(str + i * 9, " %08lx", val);
else
sprintf(str + i * 9, " ????????");
@@ -56,8 +49,6 @@ void dump_mem(const char *lvl, unsigned long bottom, unsigned long top)
}
pr_emerg("%s%04lx:%s\n", lvl, first & 0xffff, str);
}
-
- set_fs(fs);
}
EXPORT_SYMBOL(dump_mem);
--
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