memcpy without considering the get_zeroed_page() size returned

From	Peter Teoh <htmldeveloper@gmail.com>
Newsgroups	linux.kernel
Subject	memcpy without considering the get_zeroed_page() size returned
Date	2017-03-21 03:40 +0100
Message-ID	<tnhSh-5lt-3@gated-at.bofh.it> (permalink)
Organization	linux.* mail to news gateway

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https://github.com/torvalds/linux/blob/master/arch/arm64/kernel/vdso.c

/* kuser helpers */
memcpy((void *)vpage + 0x1000 - kuser_sz, __kuser_helper_start,
kuser_sz);
/* sigreturn code */
memcpy((void *)vpage + AARCH32_KERN_SIGRET_CODE_OFFSET,
__aarch32_sigret_code_start, sigret_sz);


I am just curious: depending on the configuration, will it ever
happened that get_zeroed_page() ever produce less amount of memory for
the above memcpy() operation to be successful? Ie, why the offset of
0x1000 is done without ever considering the actual amount of memory
allocated?

Please email me direct (no on LKML mailing list).

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memcpy without considering the get_zeroed_page() size returned Peter Teoh <htmldeveloper@gmail.com> - 2017-03-21 03:40 +0100

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