linux-dev - Linux kernel development work

Age	Commit message (Collapse)	Author	Files	Lines
2020-02-26	ethtool: limit bitset size	Michal Kubecek	1	-0/+2
	Syzbot reported that ethnl_compact_sanity_checks() can be tricked into reading past the end of ETHTOOL_A_BITSET_VALUE and ETHTOOL_A_BITSET_MASK attributes and even the message by passing a value between (u32)(-31) and (u32)(-1) as ETHTOOL_A_BITSET_SIZE. The problem is that DIV_ROUND_UP(attr_nbits, 32) is 0 for such values so that zero length ETHTOOL_A_BITSET_VALUE will pass the length check but ethnl_bitmap32_not_zero() check would try to access up to 512 MB of attribute "payload". Prevent this overflow byt limiting the bitset size. Technically, compact bitset format would allow bitset sizes up to almost 2^18 (so that the nest size does not exceed U16_MAX) but bitsets used by ethtool are much shorter. S16_MAX, the largest value which can be directly used as an upper limit in policy, should be a reasonable compromise. Fixes: 10b518d4e6dd ("ethtool: netlink bitset handling") Reported-by: syzbot+7fd4ed5b4234ab1fdccd@syzkaller.appspotmail.com Reported-by: syzbot+709b7a64d57978247e44@syzkaller.appspotmail.com Reported-by: syzbot+983cb8fb2d17a7af549d@syzkaller.appspotmail.com Signed-off-by: Michal Kubecek <mkubecek@suse.cz> Signed-off-by: David S. Miller <davem@davemloft.net>
2019-12-27	ethtool: netlink bitset handling	Michal Kubecek	1	-0/+28
	The ethtool netlink code uses common framework for passing arbitrary length bit sets to allow future extensions. A bitset can be a list (only one bitmap) or can consist of value and mask pair (used e.g. when client want to modify only some bits). A bitset can use one of two formats: verbose (bit by bit) or compact. Verbose format consists of bitset size (number of bits), list flag and an array of bit nests, telling which bits are part of the list or which bits are in the mask and which of them are to be set. In requests, bits can be identified by index (position) or by name. In replies, kernel provides both index and name. Verbose format is suitable for "one shot" applications like standard ethtool command as it avoids the need to either keep bit names (e.g. link modes) in sync with kernel or having to add an extra roundtrip for string set request (e.g. for private flags). Compact format uses one (list) or two (value/mask) arrays of 32-bit words to store the bitmap(s). It is more suitable for long running applications (ethtool in monitor mode or network management daemons) which can retrieve the names once and then pass only compact bitmaps to save space. Userspace requests can use either format; ETHTOOL_FLAG_COMPACT_BITSETS flag in request header tells kernel which format to use in reply. Notifications always use compact format. As some code uses arrays of unsigned long for internal representation and some arrays of u32 (or even a single u32), two sets of parse/compose helpers are introduced. To avoid code duplication, helpers for unsigned long arrays are implemented as wrappers around helpers for u32 arrays. There are two reasons for this choice: (1) u32 arrays are more frequent in ethtool code and (2) unsigned long array can be always interpreted as an u32 array on little endian 64-bit and all 32-bit architectures while we would need special handling for odd number of u32 words in the opposite direction. Signed-off-by: Michal Kubecek <mkubecek@suse.cz> Reviewed-by: Florian Fainelli <f.fainelli@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>