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844f104790
After the blamed commit, we started doing this dereference for every
NETDEV_CHANGEUPPER and NETDEV_PRECHANGEUPPER event in the system.
static inline struct dsa_port *dsa_user_to_port(const struct net_device *dev)
{
struct dsa_user_priv *p = netdev_priv(dev);
return p->dp;
}
Which is obviously bogus, because not all net_devices have a netdev_priv()
of type struct dsa_user_priv. But struct dsa_user_priv is fairly small,
and p->dp means dereferencing 8 bytes starting with offset 16. Most
drivers allocate that much private memory anyway, making our access not
fault, and we discard the bogus data quickly afterwards, so this wasn't
caught.
But the dummy interface is somewhat special in that it calls
alloc_netdev() with a priv size of 0. So every netdev_priv() dereference
is invalid, and we get this when we emit a NETDEV_PRECHANGEUPPER event
with a VLAN as its new upper:
$ ip link add dummy1 type dummy
$ ip link add link dummy1 name dummy1.100 type vlan id 100
[ 43.309174] ==================================================================
[ 43.316456] BUG: KASAN: slab-out-of-bounds in dsa_user_prechangeupper+0x30/0xe8
[ 43.323835] Read of size 8 at addr ffff3f86481d2990 by task ip/374
[ 43.330058]
[ 43.342436] Call trace:
[ 43.366542] dsa_user_prechangeupper+0x30/0xe8
[ 43.371024] dsa_user_netdevice_event+0xb38/0xee8
[ 43.375768] notifier_call_chain+0xa4/0x210
[ 43.379985] raw_notifier_call_chain+0x24/0x38
[ 43.384464] __netdev_upper_dev_link+0x3ec/0x5d8
[ 43.389120] netdev_upper_dev_link+0x70/0xa8
[ 43.393424] register_vlan_dev+0x1bc/0x310
[ 43.397554] vlan_newlink+0x210/0x248
[ 43.401247] rtnl_newlink+0x9fc/0xe30
[ 43.404942] rtnetlink_rcv_msg+0x378/0x580
Avoid the kernel oops by dereferencing after the type check, as customary.
Fixes:
|
||
|---|---|---|
| arch | ||
| block | ||
| certs | ||
| crypto | ||
| Documentation | ||
| drivers | ||
| fs | ||
| include | ||
| init | ||
| io_uring | ||
| ipc | ||
| kernel | ||
| lib | ||
| LICENSES | ||
| mm | ||
| net | ||
| rust | ||
| samples | ||
| scripts | ||
| security | ||
| sound | ||
| tools | ||
| usr | ||
| virt | ||
| .clang-format | ||
| .cocciconfig | ||
| .get_maintainer.ignore | ||
| .gitattributes | ||
| .gitignore | ||
| .mailmap | ||
| .rustfmt.toml | ||
| COPYING | ||
| CREDITS | ||
| Kbuild | ||
| Kconfig | ||
| MAINTAINERS | ||
| Makefile | ||
| README | ||
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.