In the Linux kernel, the following vulnerability has been resolved:
bpf: Make bpf_refcount_acquire fallible for non-owning refs
This patch fixes an incorrect assumption made in the original bpf_refcount series [0], specifically that the BPF program calling bpf_refcount_acquire on some node can always guarantee that the node is alive. In that series, the patch adding failure behavior to rbtree_add and list_push_{front, back} breaks this assumption for non-owning references.
Consider the following program:
n = bpf_kptr_xchg(&mapval, NULL); /* skip error checking */
bpf_spin_lock(&l); if(bpf_rbtree_add(&t, &n->rb, less)) { bpf_refcount_acquire(n); /* Failed to add, do something else with the node */ } bpf_spin_unlock(&l);
It's incorrect to assume that bpf_refcount_acquire will always succeed in this scenario. bpf_refcount_acquire is being called in a critical section here, but the lock being held is associated with rbtree t, which isn't necessarily the lock associated with the tree that the node is already in. So after bpf_rbtree_add fails to add the node and calls bpf_obj_drop in it, the program has no ownership of the node's lifetime. Therefore the node's refcount can be decr'd to 0 at any time after the failing rbtree_add. If this happens before the refcount_acquire above, the node might be free'd, and regardless refcount_acquire will be incrementing a 0 refcount.
Later patches in the series exercise this scenario, resulting in the expected complai…
In the Linux kernel, the following vulnerability has been resolved:
bpf: Make bpf_refcount_acquire fallible for non-owning refs
This patch fixes an incorrect assumption made in the original bpf_refcount series [0], specifically that the BPF program calling bpf_refcount_acquire on some node can always guarantee that the node is alive. In that series, the patch adding failure behavior to rbtree_add and list_push_{front, back} breaks this assumption for non-owning references.
Consider the following program:
n = bpf_kptr_xchg(&mapval, NULL); /* skip error checking */
bpf_spin_lock(&l); if(bpf_rbtree_add(&t, &n->rb, less)) { bpf_refcount_acquire(n); /* Failed to add, do something else with the node */ } bpf_spin_unlock(&l);
It's incorrect to assume that bpf_refcount_acquire will always succeed in this scenario. bpf_refcount_acquire is being called in a critical section here, but the lock being held is associated with rbtree t, which isn't necessarily the lock associated with the tree that the node is already in. So after bpf_rbtree_add fails to add the node and calls bpf_obj_drop in it, the program has no ownership of the node's lifetime. Therefore the node's refcount can be decr'd to 0 at any time after the failing rbtree_add. If this happens before the refcount_acquire above, the node might be free'd, and regardless refcount_acquire will be incrementing a 0 refcount.
Later patches in the series exercise this scenario, resulting in the expected complai…
kernel: Bluetooth BR/EDR PIN Pairing procedure is vulnerable to an impersonation attack kernel: ovl: fix warning in ovl_create_real() kernel: memcg does not limit the number of POSIX file locks allowing memory exhaustion kernel: vmwgfx: NULL pointer dereference in vmw_cmd_dx_define_query kernel: integer overflow in l2cap_config_req() in net/bluetooth/l2cap_core.c kernel: i2c: mlxbf: prevent stack overflow in mlxbf_i2c_smbus_start_transaction() kernel: Bluetooth: L2CAP: Fix u8 overflow kernel: hwmon: (coretemp) fix pci device refcount leak in nv1a_ram_new() kernel: tracing: Fix sleeping function called from invalid context on RT kernel kernel: net: mdio: unexport __init-annotated mdio_bus_init() kernel: arm64: ftrace: consistently handle PLTs. kernel: mm/uffd: fix pte marker when fork() without fork event kernel: Bluetooth: Fix a buffer overflow in mgmt_mesh_add() kernel: tty: n_gsm: add sanity check for gsm->receive in gsm_receive_buf() kernel: ftrace: Fix NULL pointer dereference in is_ftrace_trampoline when ftrace is dead kernel: tee: add overflow check in register_shm_helper() kernel: tty: n_gsm: fix deadlock and link starvation in outgoing data path kernel: PM: hibernate: defer device probing when resuming from hibernation kernel: ext4: don't allow journal inode to have encrypt flag kernel: ext4: fix delayed allocation bug in ext4_clu_mapped for bigalloc + inline kernel: erofs: fix order >= MAX_ORDER warning due to crafted negative i_size kernel: perf/x86/intel/uncore: F…
Security update for the Linux Kernel
Affected: Ubuntu:16.04:LTS: linux-hwe-edge, Ubuntu:18.04:LTS: linux-aws-5.0, Ubuntu:18.04:LTS: linux-aws-5.3, Ubuntu:18.04:LTS: linux-azure, Ubuntu:18.04:LTS: linux-azure-5.3, Ubuntu:18.04:LTS: linux-azure-edge, Ubuntu:18.04:LTS: linux-gcp, Ubuntu:18.04:LTS: linux-gcp-5.3, Ubuntu:18.04:LTS: linux-gke-4.15, Ubuntu:18.04:LTS: linux-gke-5.4 and 78 more
In the Linux kernel, the following vulnerability has been resolved: bpf: Make bpf_refcount_acquire fallible for non-owning refs This patch fixes an incorrect assumption made in the original bpf_refcount series [0], specifically that the BPF program calling bpf_refcount_acquire on some node can always guarantee that the node is alive. In that series, the patch adding failure behavior to rbtree_add and list_push_{front, back} breaks this assumption for non-owning references. Consider the following program: n = bpf_kptr_xchg(&mapval, NULL); /* skip error checking */ bpf_spin_lock(&l); if(bpf_rbtree_add(&t, &n->rb, less)) { bpf_refcount_acquire(n); /* Failed to add, do something else with the node */ } bpf_spin_unlock(&l); It's incorrect to assume that bpf_refcount_acquire will always succeed in this scenario. bpf_refcount_acquire is being called in a critical section here, but the lock being held is associated with rbtree t, which isn't necessarily the lock associated with the tree that the node is already in. So after bpf_rbtree_add fails to add the node and calls bpf_obj_drop in it, the program has no ownership of the node's lifetime. Therefore the node's refcount can be decr'd to 0 at any time after the failing rbtree_add. If this happens before the refcount_acquire above, the node might be free'd, and regardless refcount_acquire will be incrementing a 0 refcount. Later patches in the series exercise this scenario, resulting in the expected complaint from…
Ein Angreifer kann mehrere Schwachstellen im Linux Kernel ausnutzen, um einen Denial of Service Angriff durchzuführen und andere nicht näher spezifizierte Angriffe durchzuführen.