| Message ID | 3487ee3a98e14cd526f55b6caaa959d2dcbcad9f.1607465316.git.mkubecek@suse.cz |
|---|---|
| State | New |
| Headers | show |
| Series | [net] ethtool: fix stack overflow in ethnl_parse_bitset() | expand |
On Tue, 8 Dec 2020 23:13:51 +0100 (CET) Michal Kubecek wrote: > Syzbot reported a stack overflow in bitmap_from_arr32() called from > ethnl_parse_bitset() when bitset from netlink message is longer than > target bitmap length. While ethnl_compact_sanity_checks() makes sure that > trailing part is all zeros (i.e. the request does not try to touch bits > kernel does not recognize), we also need to cap change_bits to nbits so > that we don't try to write past the prepared bitmaps. > > Fixes: 88db6d1e4f62 ("ethtool: add ethnl_parse_bitset() helper") > Reported-by: syzbot+9d39fa49d4df294aab93@syzkaller.appspotmail.com > Signed-off-by: Michal Kubecek <mkubecek@suse.cz> Applied, thank you!
diff --git a/net/ethtool/bitset.c b/net/ethtool/bitset.c index 1fb3603d92ad..0515d6604b3b 100644 --- a/net/ethtool/bitset.c +++ b/net/ethtool/bitset.c @@ -628,6 +628,8 @@ int ethnl_parse_bitset(unsigned long *val, unsigned long *mask, return ret; change_bits = nla_get_u32(tb[ETHTOOL_A_BITSET_SIZE]); + if (change_bits > nbits) + change_bits = nbits; bitmap_from_arr32(val, nla_data(tb[ETHTOOL_A_BITSET_VALUE]), change_bits); if (change_bits < nbits)
Syzbot reported a stack overflow in bitmap_from_arr32() called from ethnl_parse_bitset() when bitset from netlink message is longer than target bitmap length. While ethnl_compact_sanity_checks() makes sure that trailing part is all zeros (i.e. the request does not try to touch bits kernel does not recognize), we also need to cap change_bits to nbits so that we don't try to write past the prepared bitmaps. Fixes: 88db6d1e4f62 ("ethtool: add ethnl_parse_bitset() helper") Reported-by: syzbot+9d39fa49d4df294aab93@syzkaller.appspotmail.com Signed-off-by: Michal Kubecek <mkubecek@suse.cz> --- net/ethtool/bitset.c | 2 ++ 1 file changed, 2 insertions(+)