[PATCH] drivers/net/cxgb3/cxgb3_main.c: prevent reading uninitializedstack memory

[Dan Rosenberg]

The CHELSIO_GET_QSET_NUM device ioctl allows unprivileged users to
read 4 bytes of uninitialized stack memory, because the "addr" member
of the ch_reg struct declared on the stack in cxgb_extension_ioctl()
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/net/cxgb3/cxgb3_main.c	2010-09-11
19:12:43.000000000 -0400
+++ linux-2.6.35.4/drivers/net/cxgb3/cxgb3_main.c	2010-09-11
19:18:42.000000000 -0400
@@ -2296,6 +2296,8 @@ static int cxgb_extension_ioctl(struct n
 	case CHELSIO_GET_QSET_NUM:{
 		struct ch_reg edata;

+		memset(&edata, 0, sizeof(struct ch_reg));
+
 		edata.cmd = CHELSIO_GET_QSET_NUM;
 		edata.val = pi->nqsets;
 		if (copy_to_user(useraddr, &edata, sizeof(edata)))
--
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