Messages in this thread | | | Date | Wed, 20 May 2020 13:13:24 +0200 | From | Christoph Hellwig <> | Subject | Re: [PATCH 13/20] maccess: always use strict semantics for probe_kernel_read |
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On Wed, May 20, 2020 at 08:11:26PM +0900, Masami Hiramatsu wrote: > > - ret = probe_kernel_read(&c, (u8 *)addr + len, 1); > > + if (IS_ENABLED(CONFIG_ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE) && > > + (unsigned long)addr < TASK_SIZE) { > > + ret = probe_user_read(&c, > > + (__force u8 __user *)addr + len, 1); > > + } else { > > + ret = probe_kernel_read(&c, (u8 *)addr + len, 1); > > + } > > len++; > > } while (c && ret == 0 && len < MAX_STRING_SIZE); > > To avoid redundant check in the loop, we can use strnlen_user_nofault() out of > the loop. Something like below.
Yes, I've done something very similar in response to Linus' comment (just using an ifdef instead).
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