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.

Chris Metcalf committed 11 years ago

Commit 990486c1 parent c753bf31 file · +2 −1Browse files

Showing the changes to lib/string.c (1 of 1 file). Show all

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lib/string.c+2−1

@@ -203,12 +203,13 @@ ssize_t strscpy(char dest, const char src, size_t count) · 202 unmodified lines
203	203	unsigned long c, data;
204	204
205	205	c = (unsigned long )(src+res);
206		− (unsigned long )(dest+res) = c;
207	206	if (has_zero(c, &data, &constants)) {
208	207	data = prep_zero_mask(c, data, &constants);
209	208	data = create_zero_mask(data);
	209	+ (unsigned long )(dest+res) = c & zero_bytemask(data);
210	210	return res + find_zero(data);
211	211	}
	212	+ (unsigned long )(dest+res) = c;
212	213	res += sizeof(unsigned long);
213	214	count -= sizeof(unsigned long);
214	215	max -= sizeof(unsigned long);