From: Gustavo A. R. Silva Date: Fri, 21 Dec 2018 20:49:01 +0000 (-0600) Subject: net: core: Fix Spectre v1 vulnerability X-Git-Url: http://git.lede-project.org./?a=commitdiff_plain;h=50d5258634aee2e62832aa086d2fb0de00e72b91;p=openwrt%2Fstaging%2Fblogic.git 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 Signed-off-by: David S. Miller --- 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 #include #include +#include /** * 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];