Messages in this thread | | | Subject | Re: [PATCH] net: clear heap allocations for privileged ethtool actions | From | Eric Dumazet <> | Date | Thu, 07 Oct 2010 23:31:25 +0200 |
| |
Le jeudi 07 octobre 2010 à 14:10 -0700, Kees Cook a écrit : > Several other ethtool functions leave heap uncleared (potentially) by > drivers. Some interfaces appear safe (eeprom, etc), in that the sizes > are well controlled. In some situations (e.g. unchecked error conditions), > the heap will remain unchanged in areas before copying back to userspace. > Note that these are less of an issue since these all require CAP_NET_ADMIN.
> @@ -775,7 +775,7 @@ static int ethtool_get_regs(struct net_device *dev, char __user *useraddr) > if (regs.len > reglen) > regs.len = reglen; > > - regbuf = kmalloc(reglen, GFP_USER); > + regbuf = kzalloc(reglen, GFP_USER); > if (!regbuf) > return -ENOMEM; > > -- > 1.7.1 >
Are you sure this is not hiding a more problematic problem ?
Code does :
reglen = ops->get_regs_len(dev); if (regs.len > reglen) regs.len = reglen; regbuf = kmalloc(reglen, GFP_USER);
So we can not copy back kernel memory.
However, what happens if user provides regs.len = 1 byte, and driver get_regs() doesnt properly checks regs.len and write past end of regbuf -> We probably write on other parts of kernel memory
An audit is needed, but first driver I checked is buggy (drivers/net/qlcnic/qlcnic_ethtool.c)
-> memset(p, 0, qlcnic_get_regs_len(dev));
-- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
| |