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

mac80211: fix potential double free on mesh join

While commit 6a01afcf8468 ("mac80211: mesh: Free ie data when leaving mesh") fixed a memory leak on mesh leave / teardown it introduced a potential memory corruption caused by a double free when rejoining the mesh:

ieee80211_leave_mesh() -> kfree(sdata->u.mesh.ie); ... ieee80211_join_mesh() -> copy_mesh_setup() -> old_ie = ifmsh->ie; -> kfree(old_ie);

This double free / kernel panics can be reproduced by using wpa_supplicant with an encrypted mesh (if set up without encryption via "iw" then ifmsh->ie is always NULL, which avoids this issue). And then calling:

$ iw dev mesh0 mesh leave $ iw dev mesh0 mesh join my-mesh

Note that typically these commands are not used / working when using wpa_supplicant. And it seems that wpa_supplicant or wpa_cli are going through a NETDEV_DOWN/NETDEV_UP cycle between a mesh leave and mesh join where the NETDEV_UP resets the mesh.ie to NULL via a memcpy of default_mesh_setup in cfg80211_netdev_notifier_call, which then avoids the memory corruption, too.

The issue was first observed in an application which was not using wpa_supplicant but "Senf" instead, which implements its own calls to nl80211.

Fixing the issue by removing the kfree()'ing of the mesh IE in the mesh join function and leaving it solely up to the mesh leave to free the mesh IE.

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

mac80211: fix potential double free on mesh join

While commit 6a01afcf8468 ("mac80211: mesh: Free ie data when leaving mesh") fixed a memory leak on mesh leave / teardown it introduced a potential memory corruption caused by a double free when rejoining the mesh:

ieee80211_leave_mesh() -> kfree(sdata->u.mesh.ie); ... ieee80211_join_mesh() -> copy_mesh_setup() -> old_ie = ifmsh->ie; -> kfree(old_ie);

This double free / kernel panics can be reproduced by using wpa_supplicant with an encrypted mesh (if set up without encryption via "iw" then ifmsh->ie is always NULL, which avoids this issue). And then calling:

$ iw dev mesh0 mesh leave $ iw dev mesh0 mesh join my-mesh

Note that typically these commands are not used / working when using wpa_supplicant. And it seems that wpa_supplicant or wpa_cli are going through a NETDEV_DOWN/NETDEV_UP cycle between a mesh leave and mesh join where the NETDEV_UP resets the mesh.ie to NULL via a memcpy of default_mesh_setup in cfg80211_netdev_notifier_call, which then avoids the memory corruption, too.

The issue was first observed in an application which was not using wpa_supplicant but "Senf" instead, which implements its own calls to nl80211.

Fixing the issue by removing the kfree()'ing of the mesh IE in the mesh join function and leaving it solely up to the mesh leave to free the mesh IE.

kernel: off-path attacker may inject data or terminate victim's TCP session kernel: race condition in VT_RESIZEX ioctl when vc_cons[i].d is already NULL leading to NULL pointer dereference kernel: use-after-free vulnerability in function sco_sock_sendmsg() kernel: memory leak for large arguments in video_usercopy function in drivers/media/v4l2-core/v4l2-ioctl.c kernel: veth: ensure skb entering GRO are not cloned. kernel: inet: fully convert sk->sk_rx_dst to RCU rules kernel: NFSD: Fix READDIR buffer overflow kernel: cpufreq: CPPC: Fix potential memleak in cppc_cpufreq_cpu_init kernel: nvme-rdma: destroy cm id before destroy qp to avoid use after free kernel: regmap: Fix possible double-free in regcache_rbtree_exit() kernel: ethtool: do not perform operations on net devices being unregistered kernel: scsi: scsi_debug: Fix type in min_t to avoid stack OOB kernel: KVM: x86/mmu: Zap _all_ roots when unmapping gfn range in TDP MMU kernel: udmabuf: validate ubuf->pagecount kernel: drm/virtio: Ensure that objs is not NULL in virtio_gpu_array_put_free() kernel: smb2_ioctl_query_info NULL pointer dereference kernel: NULL pointer dereference in udf_expand_file_adinicbdue() during writeback kernel: swiotlb information leak with DMA_FROM_DEVICE kernel: uninitialized registers on stack in nft_do_chain can cause kernel pointer leakage to UM kernel: race condition in snd_pcm_hw_free leading to use-after-free kernel: use-after-free in tc_new_tfilter() in net/sched/cls_api.c kernel: KVM: cm…

kernel: mac80211: fix potential double free on mesh join kernel: ipv6: Fix out-of-bounds access in ipv6_find_tlv() kernel: media: rc: fix races with imon_disconnect() kernel: Linux kernel: vsock vulnerability may lead to memory corruption kernel: drm/vmwgfx: Validate command header size against SVGA_CMD_MAX_DATASIZE

Security update for the Linux Kernel

Affected: Ubuntu:Pro:14.04:LTS: linux-azure, Ubuntu:Pro:14.04:LTS: linux-aws, Ubuntu:Pro:14.04:LTS: linux-lts-xenial, Ubuntu:Pro:16.04:LTS: linux-aws-hwe, Ubuntu:Pro:16.04:LTS: linux-azure, Ubuntu:Pro:16.04:LTS: linux-gcp, Ubuntu:Pro:16.04:LTS: linux-hwe, Ubuntu:Pro:16.04:LTS: linux-oracle, Ubuntu:Pro:16.04:LTS: linux, Ubuntu:Pro:16.04:LTS: linux-aws and 129 more

In the Linux kernel, the following vulnerability has been resolved: mac80211: fix potential double free on mesh join While commit 6a01afcf8468 ("mac80211: mesh: Free ie data when leaving mesh") fixed a memory leak on mesh leave / teardown it introduced a potential memory corruption caused by a double free when rejoining the mesh: ieee80211_leave_mesh() -> kfree(sdata->u.mesh.ie); ... ieee80211_join_mesh() -> copy_mesh_setup() -> old_ie = ifmsh->ie; -> kfree(old_ie); This double free / kernel panics can be reproduced by using wpa_supplicant with an encrypted mesh (if set up without encryption via "iw" then ifmsh->ie is always NULL, which avoids this issue). And then calling: $ iw dev mesh0 mesh leave $ iw dev mesh0 mesh join my-mesh Note that typically these commands are not used / working when using wpa_supplicant. And it seems that wpa_supplicant or wpa_cli are going through a NETDEV_DOWN/NETDEV_UP cycle between a mesh leave and mesh join where the NETDEV_UP resets the mesh.ie to NULL via a memcpy of default_mesh_setup in cfg80211_netdev_notifier_call, which then avoids the memory corruption, too. The issue was first observed in an application which was not using wpa_supplicant but "Senf" instead, which implements its own calls to nl80211. Fixing the issue by removing the kfree()'ing of the mesh IE in the mesh join function and leaving it solely up to the mesh leave to free the mesh IE.