Messages in this thread | | | Subject | Re: [PATCH] s390: speedup strn{cpy,len} from user. | From | Arnd Bergmann <> | Date | Sat, 12 Jun 2004 00:46:01 +0200 |
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Andrew Morton <akpm@osdl.org> schrieb am 12.06.2004, 00:19:18: > Martin Schwidefsky wrote: > > static inline long > > strncpy_from_user(char *dst, const char *src, long count) > > { > > long res = -EFAULT; > > might_sleep(); > > - if (access_ok(VERIFY_READ, src, 1)) > > - res = __strncpy_from_user_asm(dst, src, count); > > + if (access_ok(VERIFY_READ, src, 1)) { > > + res = __strncpy_from_user_asm(count, dst, src); > > + } > > return res; > > } > > Shouldn't the access_ok() check be passed `count', rather than `1'?
No, AFAIU, the logic in strncpy_from_user is that it succeeds for any string that is limited by either 'count' or a trailing zero or the end of the user mapping, whichever comes first. This means only one byte needs to be addressable.
On s390, it doesn't matter anyway because access_ok() is always true, but the check for access_ok() is the same on all architectures.
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