[PATCH 3.18 18/92] strscpy: zero any trailing garbage bytes in the destination

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



3.18-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Chris Metcalf <cmetcalf@xxxxxxxxxx>

commit 990486c8af044f89bddfbde1d1cf9fde449bedbf upstream.

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: Chris Metcalf <cmetcalf@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 lib/string.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- a/lib/string.c
+++ b/lib/string.c
@@ -211,12 +211,13 @@ ssize_t strscpy(char *dest, const char *
 		unsigned long c, data;
 
 		c = *(unsigned long *)(src+res);
-		*(unsigned long *)(dest+res) = c;
 		if (has_zero(c, &data, &constants)) {
 			data = prep_zero_mask(c, data, &constants);
 			data = create_zero_mask(data);
+			*(unsigned long *)(dest+res) = c & zero_bytemask(data);
 			return res + find_zero(data);
 		}
+		*(unsigned long *)(dest+res) = c;
 		res += sizeof(unsigned long);
 		count -= sizeof(unsigned long);
 		max -= sizeof(unsigned long);





[Index of Archives]     [Linux Kernel]     [Kernel Development Newbies]     [Linux USB Devel]     [Video for Linux]     [Linux Audio Users]     [Yosemite Hiking]     [Linux Kernel]     [Linux SCSI]