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authorDavide Caratti <dcaratti@redhat.com>2020-12-03 10:58:21 +0100
committerJakub Kicinski <kuba@kernel.org>2020-12-03 11:13:21 -0800
commit13de4ed9e3a9ccbe54d05f7d5c773f69ecaf6c64 (patch)
tree3c31c25a52609be88914c1b5f78aa8d4c06f31f4 /net/core
parent6392b5b28e0e00171018ecd3ced3554f95b9bb46 (diff)
net: skbuff: ensure LSE is pullable before decrementing the MPLS ttl
skb_mpls_dec_ttl() reads the LSE without ensuring that it is contained in the skb "linear" area. Fix this calling pskb_may_pull() before reading the current ttl. Found by code inspection. Fixes: 2a2ea50870ba ("net: sched: add mpls manipulation actions to TC") Reported-by: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com> Signed-off-by: Davide Caratti <dcaratti@redhat.com> Link: https://lore.kernel.org/r/53659f28be8bc336c113b5254dc637cc76bbae91.1606987074.git.dcaratti@redhat.com Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Diffstat (limited to 'net/core')
-rw-r--r--net/core/skbuff.c3
1 files changed, 3 insertions, 0 deletions
diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index 06c526e0d810..e578544b2cc7 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -5786,6 +5786,9 @@ int skb_mpls_dec_ttl(struct sk_buff *skb)
if (unlikely(!eth_p_mpls(skb->protocol)))
return -EINVAL;
+ if (!pskb_may_pull(skb, skb_network_offset(skb) + MPLS_HLEN))
+ return -ENOMEM;
+
lse = be32_to_cpu(mpls_hdr(skb)->label_stack_entry);
ttl = (lse & MPLS_LS_TTL_MASK) >> MPLS_LS_TTL_SHIFT;
if (!--ttl)