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Commit 990486c8 authored by Chris Metcalf's avatar Chris Metcalf
Browse files

strscpy: zero any trailing garbage bytes in the destination 



It's possible that the destination can be shadowed in userspace
(as, for example, the perf buffers are now).  So we should take
care not to leak data that could be inspected by userspace.

Signed-off-by: default avatarChris Metcalf <cmetcalf@ezchip.com>
parent c753bf34

lib/string.c

+2 −1
Original line number Original line Diff line number Diff line
@@ -203,12 +203,13 @@ ssize_t strscpy(char *dest, const char *src, size_t count) 
		unsigned long c, data;

		unsigned long c, data;





		c = *(unsigned long *)(src+res);

		c = *(unsigned long *)(src+res);

		*(unsigned long *)(dest+res) = c;

		if (has_zero(c, &data, &constants)) {

		if (has_zero(c, &data, &constants)) {

			data = prep_zero_mask(c, data, &constants);

			data = prep_zero_mask(c, data, &constants);

			data = create_zero_mask(data);

			data = create_zero_mask(data);

			*(unsigned long *)(dest+res) = c & zero_bytemask(data);

			return res + find_zero(data);

			return res + find_zero(data);

		}

		}

		*(unsigned long *)(dest+res) = c;

		res += sizeof(unsigned long);

		res += sizeof(unsigned long);

		count -= sizeof(unsigned long);

		count -= sizeof(unsigned long);

		max -= sizeof(unsigned long);

		max -= sizeof(unsigned long);