In the Linux kernel, the following vulnerability has been resolved: nfc: nci: fix out-of-bounds write in nci_target_auto_activated() nci_t

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

nfc: nci: fix out-of-bounds write in nci_target_auto_activated()

nci_target_auto_activated() appends a target to the fixed-size array
ndev->targets[NCI_MAX_DISCOVERED_TARGETS] and increments ndev->n_targets
without first checking the array is full; unlike its sibling
nci_add_new_target(), which bails out when n_targets already equals
NCI_MAX_DISCOVERED_TARGETS.

ndev->n_targets is only cleared by nci_clear_target_list(), so an NFCC
that repeatedly re-runs discovery (RF_DISCOVER_RSP, which re-enters
NCI_DISCOVERY without clearing the target list) and reports an
auto-activated target (RF_INTF_ACTIVATED_NTF) drives n_targets past the
limit. The append then writes a struct nfc_target past the end of the
array (a slab out-of-bounds write), and nfc_targets_found() goes on to
walk the array with the inflated count:

BUG: KASAN: slab-out-of-bounds in nci_add_new_protocol+0x94/0x2ac [nci]
Write of size 2 at addr ffff0000c7299a18 by task kworker/u8:0/12
Workqueue: nfc0_nci_rx_wq nci_rx_work [nci]
Call trace:
nci_add_new_protocol+0x94/0x2ac [nci]
nci_ntf_packet+0xddc/0x11a0 [nci]
nci_rx_work+0x15c/0x1e0 [nci]
process_one_work+0x2dc/0x500
worker_thread+0x240/0x460
kthread+0x1c0/0x1d0
ret_from_fork+0x10/0x20

The buggy address belongs to the cache kmalloc-2k of size 2048
The buggy address is located 1024 bytes to the right of
allocated 1560-byte region [ffff0000c7299000, ffff0000c7299618)

Guard nci_target_auto_activated() with the same check used by
nci_add_new_target().