From: "Gustavo A. R. Silva" <gustavo@embeddedor.com>
To: Alexei Starovoitov <ast@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
"David S. Miller" <davem@davemloft.net>
Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
"Gustavo A. R. Silva" <gustavo@embeddedor.com>
Subject: [PATCH] net: core: Fix Spectre v1 vulnerability
Date: Fri, 21 Dec 2018 14:49:01 -0600 [thread overview]
Message-ID: <20181221204901.GA30045@embeddedor> (raw)
flen is 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:
net/core/filter.c:1101 bpf_check_classic() warn: potential spectre issue 'filter' [w]
Fix this by sanitizing flen before using it to index filter at line 1101:
switch (filter[flen - 1].code) {
and through pc at line 1040:
const struct sock_filter *ftest = &filter[pc];
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].
[1] https://marc.info/?l=linux-kernel&m=152449131114778&w=2
Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
---
net/core/filter.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/net/core/filter.c b/net/core/filter.c
index 447dd1bad31f..8ec4337256ed 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -73,6 +73,7 @@
#include <linux/seg6_local.h>
#include <net/seg6.h>
#include <net/seg6_local.h>
+#include <linux/nospec.h>
/**
* sk_filter_trim_cap - run a packet through a socket filter
@@ -1035,6 +1036,7 @@ static int bpf_check_classic(const struct sock_filter *filter,
bool anc_found;
int pc;
+ flen = array_index_nospec(flen, BPF_MAXINSNS + 1);
/* Check the filter code now */
for (pc = 0; pc < flen; pc++) {
const struct sock_filter *ftest = &filter[pc];
--
2.20.1
next reply other threads:[~2018-12-21 20:49 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-12-21 20:49 Gustavo A. R. Silva [this message]
2018-12-22 23:07 ` [PATCH] net: core: Fix Spectre v1 vulnerability David Miller
2018-12-22 23:59 ` Alexei Starovoitov
2018-12-23 2:40 ` David Miller
2018-12-23 2:53 ` Gustavo A. R. Silva
2018-12-23 3:00 ` Alexei Starovoitov
2018-12-23 3:37 ` Gustavo A. R. Silva
2018-12-23 3:50 ` Gustavo A. R. Silva
2018-12-23 4:12 ` Alexei Starovoitov
2018-12-23 5:03 ` Gustavo A. R. Silva
2018-12-23 6:00 ` Alexei Starovoitov
2018-12-23 23:58 ` David Miller
2018-12-24 0:01 ` Gustavo A. R. Silva
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