From 3165b40808f58077985463e9555f1bcac0c3b174 Mon Sep 17 00:00:00 2001 From: Cong Wang Date: Sun, 2 Feb 2020 21:14:35 -0800 Subject: [PATCH] net_sched: fix an OOB access in cls_tcindex As Eric noticed, tcindex_alloc_perfect_hash() uses cp->hash to compute the size of memory allocation, but cp->hash is set again after the allocation, this caused an out-of-bound access. So we have to move all cp->hash initialization and computation before the memory allocation. Move cp->mask and cp->shift together as cp->hash may need them for computation too. Reported-and-tested-by: syzbot+35d4dea36c387813ed31@syzkaller.appspotmail.com Fixes: a4b67f07dc6f ("net: sched: RCU cls_tcindex") Cc: Eric Dumazet Cc: John Fastabend Cc: Jamal Hadi Salim Cc: Jiri Pirko Cc: Jakub Kicinski Signed-off-by: Cong Wang Signed-off-by: David S. Miller --- net/sched/cls_tcindex.c | 40 ++++++++++++++++++++-------------------- 1 file changed, 20 insertions(+), 20 deletions(-) diff --git a/net/sched/cls_tcindex.c b/net/sched/cls_tcindex.c index 3d4a1280352f3..0323aee03de7e 100644 --- a/net/sched/cls_tcindex.c +++ b/net/sched/cls_tcindex.c @@ -333,12 +333,31 @@ tcindex_set_parms(struct net *net, struct tcf_proto *tp, unsigned long base, cp->fall_through = p->fall_through; cp->tp = tp; + if (tb[TCA_TCINDEX_HASH]) + cp->hash = nla_get_u32(tb[TCA_TCINDEX_HASH]); + + if (tb[TCA_TCINDEX_MASK]) + cp->mask = nla_get_u16(tb[TCA_TCINDEX_MASK]); + + if (tb[TCA_TCINDEX_SHIFT]) + cp->shift = nla_get_u32(tb[TCA_TCINDEX_SHIFT]); + + if (!cp->hash) { + /* Hash not specified, use perfect hash if the upper limit + * of the hashing index is below the threshold. + */ + if ((cp->mask >> cp->shift) < PERFECT_HASH_THRESHOLD) + cp->hash = (cp->mask >> cp->shift) + 1; + else + cp->hash = DEFAULT_HASH_SIZE; + } + if (p->perfect) { int i; if (tcindex_alloc_perfect_hash(net, cp) < 0) goto errout; - for (i = 0; i < cp->hash; i++) + for (i = 0; i < min(cp->hash, p->hash); i++) cp->perfect[i].res = p->perfect[i].res; balloc = 1; } @@ -350,15 +369,6 @@ tcindex_set_parms(struct net *net, struct tcf_proto *tp, unsigned long base, if (old_r) cr = r->res; - if (tb[TCA_TCINDEX_HASH]) - cp->hash = nla_get_u32(tb[TCA_TCINDEX_HASH]); - - if (tb[TCA_TCINDEX_MASK]) - cp->mask = nla_get_u16(tb[TCA_TCINDEX_MASK]); - - if (tb[TCA_TCINDEX_SHIFT]) - cp->shift = nla_get_u32(tb[TCA_TCINDEX_SHIFT]); - err = -EBUSY; /* Hash already allocated, make sure that we still meet the @@ -376,16 +386,6 @@ tcindex_set_parms(struct net *net, struct tcf_proto *tp, unsigned long base, if (tb[TCA_TCINDEX_FALL_THROUGH]) cp->fall_through = nla_get_u32(tb[TCA_TCINDEX_FALL_THROUGH]); - if (!cp->hash) { - /* Hash not specified, use perfect hash if the upper limit - * of the hashing index is below the threshold. - */ - if ((cp->mask >> cp->shift) < PERFECT_HASH_THRESHOLD) - cp->hash = (cp->mask >> cp->shift) + 1; - else - cp->hash = DEFAULT_HASH_SIZE; - } - if (!cp->perfect && !cp->h) cp->alloc_hash = cp->hash; -- 2.39.5