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authorMichal Kubecek <mkubecek@suse.cz>2020-12-09 01:13:51 +0300
committerJakub Kicinski <kuba@kernel.org>2020-12-10 02:50:38 +0300
commita770bf515613c6e12ae904c3593e26016de99448 (patch)
tree070e9e0651e009cf87054dbdad0e7796b35fbb7c /net/ethtool
parenta379b01cd4b2aa3f12786b281a714871574e5ccb (diff)
downloadlinux-a770bf515613c6e12ae904c3593e26016de99448.tar.xz
ethtool: fix stack overflow in ethnl_parse_bitset()
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>
Diffstat (limited to 'net/ethtool')
-rw-r--r--net/ethtool/bitset.c2
1 files changed, 2 insertions, 0 deletions
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)