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author | Vivien Didelot <vivien.didelot@gmail.com> | 2019-06-03 16:57:13 -0400 |
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committer | David S. Miller <davem@davemloft.net> | 2019-06-05 17:15:27 -0700 |
commit | 0ee4e76937d69128a6a66861ba393ebdc2ffc8a2 (patch) | |
tree | af339fbc4798df5ef78a3c3241327ef8c3556999 /net/core | |
parent | 0a8dd9f67cd0da7dc284f48b032ce00db1a68791 (diff) | |
download | linux-stable-0ee4e76937d69128a6a66861ba393ebdc2ffc8a2.tar.gz linux-stable-0ee4e76937d69128a6a66861ba393ebdc2ffc8a2.tar.bz2 linux-stable-0ee4e76937d69128a6a66861ba393ebdc2ffc8a2.zip |
ethtool: fix potential userspace buffer overflow
ethtool_get_regs() allocates a buffer of size ops->get_regs_len(),
and pass it to the kernel driver via ops->get_regs() for filling.
There is no restriction about what the kernel drivers can or cannot do
with the open ethtool_regs structure. They usually set regs->version
and ignore regs->len or set it to the same size as ops->get_regs_len().
But if userspace allocates a smaller buffer for the registers dump,
we would cause a userspace buffer overflow in the final copy_to_user()
call, which uses the regs.len value potentially reset by the driver.
To fix this, make this case obvious and store regs.len before calling
ops->get_regs(), to only copy as much data as requested by userspace,
up to the value returned by ops->get_regs_len().
While at it, remove the redundant check for non-null regbuf.
Signed-off-by: Vivien Didelot <vivien.didelot@gmail.com>
Reviewed-by: Michal Kubecek <mkubecek@suse.cz>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/core')
-rw-r--r-- | net/core/ethtool.c | 5 |
1 files changed, 4 insertions, 1 deletions
diff --git a/net/core/ethtool.c b/net/core/ethtool.c index 43e9add58340..1a0196fbb49c 100644 --- a/net/core/ethtool.c +++ b/net/core/ethtool.c @@ -1359,13 +1359,16 @@ static int ethtool_get_regs(struct net_device *dev, char __user *useraddr) if (!regbuf) return -ENOMEM; + if (regs.len < reglen) + reglen = regs.len; + ops->get_regs(dev, ®s, regbuf); ret = -EFAULT; if (copy_to_user(useraddr, ®s, sizeof(regs))) goto out; useraddr += offsetof(struct ethtool_regs, data); - if (regbuf && copy_to_user(useraddr, regbuf, regs.len)) + if (copy_to_user(useraddr, regbuf, reglen)) goto out; ret = 0; |