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Subject[PATCH 4.9 34/66] net: cxgb3_main: fix potential Spectre v1
4.9-stable review patch.  If anyone has any objections, please let me know.


From: Gustavo A. R. Silva <>

commit 676bcfece19f83621e905aa55b5ed2d45cc4f2d3 upstream.

t.qset_idx can be indirectly controlled by user-space, hence leading to
a potential exploitation of the Spectre variant 1 vulnerability.

This issue was detected with the help of Smatch:

drivers/net/ethernet/chelsio/cxgb3/cxgb3_main.c:2286 cxgb_extension_ioctl()
warn: potential spectre issue 'adapter->msix_info'

Fix this by sanitizing t.qset_idx before using it to index

Notice that given that speculation windows are large, the policy is
to kill the speculation on the first load and not worry if it can be
completed with a dependent load/store [1].


Signed-off-by: Gustavo A. R. Silva <>
Signed-off-by: David S. Miller <>
Signed-off-by: Greg Kroah-Hartman <>

drivers/net/ethernet/chelsio/cxgb3/cxgb3_main.c | 2 ++
1 file changed, 2 insertions(+)

--- a/drivers/net/ethernet/chelsio/cxgb3/cxgb3_main.c
+++ b/drivers/net/ethernet/chelsio/cxgb3/cxgb3_main.c
@@ -50,6 +50,7 @@
#include <linux/stringify.h>
#include <linux/sched.h>
#include <linux/slab.h>
+#include <linux/nospec.h>
#include <asm/uaccess.h>

#include "common.h"
@@ -2259,6 +2260,7 @@ static int cxgb_extension_ioctl(struct n

if (t.qset_idx >= nqsets)
return -EINVAL;
+ t.qset_idx = array_index_nospec(t.qset_idx, nqsets);

q = &adapter->params.sge.qset[q1 + t.qset_idx];
t.rspq_size = q->rspq_size;

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