[PATCH] drivers/char/amiserial.c: prevent reading uninitializedstack memory

[Dan Rosenberg]

The TIOCGICOUNT device ioctl allows unprivileged users to read
uninitialized stack memory, because the "reserved" member of the
serial_icounter_struct struct declared on the stack is not altered or
zeroed before being copied back to the user.  This patch takes care of
it.

Signed-off-by: Dan Rosenberg <dan.j.rosenberg@xxxxxxxxx>

--- linux-2.6.35.4.orig/drivers/char/amiserial.c	2010-08-26 19:47:12.000000000 -0400
+++ linux-2.6.35.4/drivers/char/amiserial.c	2010-09-15 13:58:00.217343289 -0400
@@ -1342,6 +1342,9 @@ static int rs_ioctl(struct tty_struct *t
 			local_irq_save(flags);
 			cnow = info->state->icount;
 			local_irq_restore(flags);
+
+			memset(&icount, 0, sizeof(struct serial_icounter_struct));
+
 			icount.cts = cnow.cts;
 			icount.dsr = cnow.dsr;
 			icount.rng = cnow.rng;





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