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authorGustavo A. R. Silva <gustavo@embeddedor.com>2018-12-21 14:49:01 -0600
committerDavid S. Miller <davem@davemloft.net>2018-12-22 15:06:17 -0800
commit50d5258634aee2e62832aa086d2fb0de00e72b91 (patch)
treefb5bd2cf4c54555cf4ab87797dd956aa811106f6 /net
parent6cafab50eea327e0d198cc9579a60440fc959756 (diff)
net: core: Fix Spectre v1 vulnerability
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> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net')
-rw-r--r--net/core/filter.c2
1 files changed, 2 insertions, 0 deletions
diff --git a/net/core/filter.c b/net/core/filter.c
index 8d2c629501e2..0c74c2f9776a 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
@@ -1038,6 +1039,7 @@ 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];

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