From: Cong Wang xiyou.wangcong@gmail.com
[ Upstream commit 599be01ee567b61f4471ee8078870847d0a11e8e ]
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: 331b72922c5f ("net: sched: RCU cls_tcindex") Cc: Eric Dumazet eric.dumazet@gmail.com Cc: John Fastabend john.fastabend@gmail.com Cc: Jamal Hadi Salim jhs@mojatatu.com Cc: Jiri Pirko jiri@resnulli.us Cc: Jakub Kicinski kuba@kernel.org Signed-off-by: Cong Wang xiyou.wangcong@gmail.com Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- net/sched/cls_tcindex.c | 40 ++++++++++++++++++++-------------------- 1 file changed, 20 insertions(+), 20 deletions(-)
--- a/net/sched/cls_tcindex.c +++ b/net/sched/cls_tcindex.c @@ -301,12 +301,31 @@ tcindex_set_parms(struct net *net, struc 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(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; } @@ -321,15 +340,6 @@ tcindex_set_parms(struct net *net, struc if (old_r) cr.res = 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 @@ -347,16 +357,6 @@ tcindex_set_parms(struct net *net, struc 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;