Messages in this thread | | | Date | Tue, 21 Jul 2020 19:07:17 +0800 | From | Nick Hu <> | Subject | Re: [PATCH 2/2] nds32: use get_kernel_nofault in dump_mem |
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On Mon, Jul 20, 2020 at 01:44:48PM +0200, Christoph Hellwig 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> > --- > 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 b66f889bc6df9b..ee0d9ae192a504 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); > -- > 2.27.0 > Hi Christoph,
Thank you! Acked-by: Nick Hu <nickhu@andestech.com>
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