| From | Greg Kroah-Hartman <> | Subject | [PATCH 5.9 22/49] ethtool: fix stack overflow in ethnl_parse_bitset() | Date | Sat, 19 Dec 2020 13:58:26 +0100 |
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From: Michal Kubecek <mkubecek@suse.cz>
[ Upstream commit a770bf515613c6e12ae904c3593e26016de99448 ]
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> Link: https://lore.kernel.org/r/3487ee3a98e14cd526f55b6caaa959d2dcbcad9f.1607465316.git.mkubecek@suse.cz Signed-off-by: Jakub Kicinski <kuba@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> --- net/ethtool/bitset.c | 2 ++ 1 file changed, 2 insertions(+)
--- a/net/ethtool/bitset.c +++ b/net/ethtool/bitset.c @@ -630,6 +630,8 @@ int ethnl_parse_bitset(unsigned long *va 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)
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