Race condition in mm/gup.c in the Linux kernel 2.x through 4.x before 4.8.3 allows local users to gain privileges by leveraging incorrect handling of a copy-on-write (COW) feature to write to a read-only memory mapping, as exploited in the wild in October 2016, aka "Dirty COW."

In the Linux kernel, the following vulnerability has been resolved: tipc: fix NULL deref in cleanup_bearer() syzbot found [1] that after blamed commit, ub->ubsock->sk was NULL when attempting the atomic_dec() : atomic_dec(&tipc_net(sock_net(ub->ubsock->sk))->wq_count); Fix this by caching the tipc_net pointer. [1] Oops: general protection fault, probably for non-canonical address 0xdffffc0000000006: 0000 [#1] PREEMPT SMP KASAN PTI KASAN: null-ptr-deref in range [0x0000000000000030-0x0000000000000037] CPU: 0 UID: 0 PID: 5896 Comm: kworker/0:3 Not tainted 6.13.0-rc1-next-20241203-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024 Workqueue: events cleanup_bearer RIP: 0010:read_pnet include/net/net_namespace.h:387 [inline] RIP: 0010:sock_net include/net/sock.h:655 [inline] RIP: 0010:cleanup_bearer+0x1f7/0x280 net/tipc/udp_media.c:820 Code: 18 48 89 d8 48 c1 e8 03 42 80 3c 28 00 74 08 48 89 df e8 3c f7 99 f6 48 8b 1b 48 83 c3 30…

In the Linux kernel, the following vulnerability has been resolved: posix-clock: posix-clock: Fix unbalanced locking in pc_clock_settime() If get_clock_desc() succeeds, it calls fget() for the clockid's fd, and get the clk->rwsem read lock, so the error path should release the lock to make the lock balance and fput the clockid's fd to make the refcount balance and release the fd related resource. However the below commit left the error path locked behind resulting in unbalanced locking. Check timespec64_valid_strict() before get_clock_desc() to fix it, because the "ts" is not changed after that. [pabeni@redhat.com: fixed commit message typo]

In the Linux kernel, the following vulnerability has been resolved: nfc: nci: fix possible NULL pointer dereference in send_acknowledge() Handle memory allocation failure from nci_skb_alloc() (calling alloc_skb()) to avoid possible NULL pointer dereference.

In the Linux kernel, the following vulnerability has been resolved: fou: fix initialization of grc The grc must be initialize first. There can be a condition where if fou is NULL, goto out will be executed and grc would be used uninitialized.

In the Linux kernel, the following vulnerability has been resolved: netfs: Only call folio_start_fscache() one time for each folio If a network filesystem using netfs implements a clamp_length() function, it can set subrequest lengths smaller than a page size. When we loop through the folios in netfs_rreq_unlock_folios() to set any folios to be written back, we need to make sure we only call folio_start_fscache() once for each folio. Otherwise, this simple testcase: mount -o fsc,rsize=1024,wsize=1024 127.0.0.1:/export /mnt/nfs dd if=/dev/zero of=/mnt/nfs/file.bin bs=4096 count=1 1+0 records in 1+0 records out 4096 bytes (4.1 kB, 4.0 KiB) copied, 0.0126359 s, 324 kB/s echo 3 > /proc/sys/vm/drop_caches cat /mnt/nfs/file.bin > /dev/null will trigger an oops similar to the following: page dumped because: VM_BUG_ON_FOLIO(folio_test_private_2(folio)) ------------[ cut here ]------------ kernel BUG at include/linux/netfs.h:44! ... CPU: 5 PID: 134 Comm: kworker/…

In the Linux kernel, the following vulnerability has been resolved: net/core: Fix ETH_P_1588 flow dissector When a PTP ethernet raw frame with a size of more than 256 bytes followed by a 0xff pattern is sent to __skb_flow_dissect, nhoff value calculation is wrong. For example: hdr->message_length takes the wrong value (0xffff) and it does not replicate real header length. In this case, 'nhoff' value was overridden and the PTP header was badly dissected. This leads to a kernel crash. net/core: flow_dissector net/core flow dissector nhoff = 0x0000000e net/core flow dissector hdr->message_length = 0x0000ffff net/core flow dissector nhoff = 0x0001000d (u16 overflow) ... skb linear: 00000000: 00 a0 c9 00 00 00 00 a0 c9 00 00 00 88 skb frag: 00000000: f7 ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff Using the size of the ptp_header struct will allow the corrected calculation of the nhoff value. net/core flow dissector nhoff = 0x0000000e net/core flow dissector nhoff = 0x00000030 (…

In the Linux kernel, the following vulnerability has been resolved: net: bridge: use DEV_STATS_INC() syzbot/KCSAN reported data-races in br_handle_frame_finish() [1] This function can run from multiple cpus without mutual exclusion. Adopt SMP safe DEV_STATS_INC() to update dev->stats fields. Handles updates to dev->stats.tx_dropped while we are at it. [1] BUG: KCSAN: data-race in br_handle_frame_finish / br_handle_frame_finish read-write to 0xffff8881374b2178 of 8 bytes by interrupt on cpu 1: br_handle_frame_finish+0xd4f/0xef0 net/bridge/br_input.c:189 br_nf_hook_thresh+0x1ed/0x220 br_nf_pre_routing_finish_ipv6+0x50f/0x540 NF_HOOK include/linux/netfilter.h:304 [inline] br_nf_pre_routing_ipv6+0x1e3/0x2a0 net/bridge/br_netfilter_ipv6.c:178 br_nf_pre_routing+0x526/0xba0 net/bridge/br_netfilter_hooks.c:508 nf_hook_entry_hookfn include/linux/netfilter.h:144 [inline] nf_hook_bridge_pre net/bridge/br_input.c:272 [inline] br_handle_frame+0x4c9/0x940 net/bridge/br_input.c:417 __netif_rec…

In the Linux kernel, the following vulnerability has been resolved: team: fix null-ptr-deref when team device type is changed Get a null-ptr-deref bug as follows with reproducer [1]. BUG: kernel NULL pointer dereference, address: 0000000000000228 ... RIP: 0010:vlan_dev_hard_header+0x35/0x140 [8021q] ... Call Trace: <TASK> ? __die+0x24/0x70 ? page_fault_oops+0x82/0x150 ? exc_page_fault+0x69/0x150 ? asm_exc_page_fault+0x26/0x30 ? vlan_dev_hard_header+0x35/0x140 [8021q] ? vlan_dev_hard_header+0x8e/0x140 [8021q] neigh_connected_output+0xb2/0x100 ip6_finish_output2+0x1cb/0x520 ? nf_hook_slow+0x43/0xc0 ? ip6_mtu+0x46/0x80 ip6_finish_output+0x2a/0xb0 mld_sendpack+0x18f/0x250 mld_ifc_work+0x39/0x160 process_one_work+0x1e6/0x3f0 worker_thread+0x4d/0x2f0 ? __pfx_worker_thread+0x10/0x10 kthread+0xe5/0x120 ? __pfx_kthread+0x10/0x10 ret_from_fork+0x34/0x50 ? __pfx_kthread+0x10/0x10 ret_from_fork_asm+0x1b/0x30 [1] $ teamd -t team0 -d -c '{"runner": {"name": "loadbalance"}}…

In the Linux kernel, the following vulnerability has been resolved: net: rds: Fix possible NULL-pointer dereference In rds_rdma_cm_event_handler_cmn() check, if conn pointer exists before dereferencing it as rdma_set_service_type() argument Found by Linux Verification Center (linuxtesting.org) with SVACE.