In the Linux kernel, the following vulnerability has been resolved:

vxlan: Fix memory leaks in error path

The memory allocated by vxlan_vnigroup_init() is not freed in the error path, leading to memory leaks [1]. Fix by calling vxlan_vnigroup_uninit() in the error path.

The leaks can be reproduced by annotating gro_cells_init() with ALLOW_ERROR_INJECTION() and then running:

echo 100 > /sys/kernel/debug/fail_function/probability

echo 1 > /sys/kernel/debug/fail_function/times

echo gro_cells_init > /sys/kernel/debug/fail_function/inject

printf %#x -12 > /sys/kernel/debug/fail_function/gro_cells_init/retval

ip link add name vxlan0 type vxlan dstport 4789 external vnifilter

RTNETLINK answers: Cannot allocate memory

[1] unreferenced object 0xffff88810db84a00 (size 512): comm ip, pid 330, jiffies 4295010045 (age 66.016s) hex dump (first 32 bytes): f8 d5 76 0e 81 88 ff ff 01 00 00 00 00 00 00 02 ..v…………. 03 00 04 00 48 00 00 00 00 00 00 01 04 00 01 00 ….H……….. backtrace: [] kmalloc_trace+0x2a/0x60 [] vxlan_vnigroup_init+0x4c/0x160 [] vxlan_init+0x1ae/0x280 [] register_netdevice+0x57a/0x16d0 [] __vxlan_dev_create+0x7c7/0xa50 [] vxlan_newlink+0xd6/0x130 [] __rtnl_newlink+0x112b/0x18a0 [] rtnl_newlink+0x6c/0xa0 [] rtnetlink_rcv_msg+0x43f/0xd40 [] netlink_rcv_skb+0x170/0x440 [] netlink_unicast+0x53f/0x810 [] netlink_sendmsg+0x958/0xe70 [] ____sys_sendmsg+0x78f/0xa90 [] ___sys_sendmsg+0x13a/0x1e0 [] __sys_sendmsg+0x11c/0x1f0 [] do_syscall_64+0x38/0x80 unreferenced object 0xffff88810e76d5f8 (size 192): comm ip, pid 330, jiffies 4295010045 (age 66.016s) hex dump (first 32 bytes): 04 00 00 00 00 00 00 00 db e1 4f e7 00 00 00 00 ……….O….. 08 d6 76 0e 81 88 ff ff 08 d6 76 0e 81 88 ff ff ..v…….v….. backtrace: [] __kmalloc_node+0x4e/0x90 [] kvmalloc_node+0xa6/0x1f0 [] bucket_table_alloc.isra.0+0x83/0x460 [] rhashtable_init+0x43b/0x7c0 [] vxlan_vnigroup_init+0x6c/0x160 [] vxlan_init+0x1ae/0x280 [] register_netdevice+0x57a/0x16d0 [] __vxlan_dev_create+0x7c7/0xa50 [] vxlan_newlink+0xd6/0x130 [] __rtnl_newlink+0x112b/0x18a0 [] rtnl_newlink+0x6c/0xa0 [] rtnetlink_rcv_msg+0x43f/0xd40 [] netlink_rcv_skb+0x170/0x440 [] netlink_unicast+0x53f/0x810 [] netlink_sendmsg+0x958/0xe70 [] ____sys_sendmsg+0x78f/0xa90

Weakness

The product does not sufficiently track and release allocated memory after it has been used, making the memory unavailable for reallocation and reuse.

Affected Software

Potential Mitigations

• Choose a language or tool that provides automatic memory management, or makes manual memory management less error-prone.
• For example, glibc in Linux provides protection against free of invalid pointers.
• When using Xcode to target OS X or iOS, enable automatic reference counting (ARC) [REF-391].
• To help correctly and consistently manage memory when programming in C++, consider using a smart pointer class such as std::auto_ptr (defined by ISO/IEC ISO/IEC 14882:2003), std::shared_ptr and std::unique_ptr (specified by an upcoming revision of the C++ standard, informally referred to as C++ 1x), or equivalent solutions such as Boost.

References

• https://git.kernel.org/stable/c/06bf62944144a92d83dd14fd1378d2a288259561
• https://git.kernel.org/stable/c/5896f55810680391a32652ca2b91245a05c11e22
• https://git.kernel.org/stable/c/75c1ab900f7cf0485f0be1607c79c55f51faaa90