Description

In the Linux kernel, the following vulnerability has been resolved: netlink: fix false positive warning in extack during dumps Commit under fixes extended extack reporting to dumps. It works under normal conditions, because extack errors are usually reported during ->start() or the first ->dump(), it's quite rare that the dump starts okay but fails later. If the dump does fail later, however, the input skb will already have the initiating message pulled, so checking if bad attr falls within skb->data will fail. Switch the check to using nlh, which is always valid. syzbot found a way to hit that scenario by filling up the receive queue. In this case we initiate a dump but don't call ->dump() until there is read space for an skb. WARNING: CPU: 1 PID: 5845 at net/netlink/af_netlink.c:2210 netlink_ack_tlv_fill+0x1a8/0x560 net/netlink/af_netlink.c:2209 RIP: 0010:netlink_ack_tlv_fill+0x1a8/0x560 net/netlink/af_netlink.c:2209 Call Trace: <TASK> netlink_dump_done+0x513/0x970 net/netlink/af_netlink.c:2250 netlink_dump+0x91f/0xe10 net/netlink/af_netlink.c:2351 netlink_recvmsg+0x6bb/0x11d0 net/netlink/af_netlink.c:1983 sock_recvmsg_nosec net/socket.c:1051 [inline] sock_recvmsg+0x22f/0x280 net/socket.c:1073 __sys_recvfrom+0x246/0x3d0 net/socket.c:2267 __do_sys_recvfrom net/socket.c:2285 [inline] __se_sys_recvfrom net/socket.c:2281 [inline] __x64_sys_recvfrom+0xde/0x100 net/socket.c:2281 do_syscall_x64 arch/x86/entry/common.c:52 [inline] do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7ff37dd17a79

Affected Products 2

References 3

• git.kernel.org https://git.kernel.org/stable/c/28af028a71371df5fcbf807fd4444bba8d0c33cc
  Patch
• git.kernel.org https://git.kernel.org/stable/c/3bf39fa849ab8ed52abb6715922e6102d3df9f97
  Patch
• git.kernel.org https://git.kernel.org/stable/c/6406d0ce0414b807af5d2a4b781c3f3ee52b8a4d
  Patch

Remediation

• git.kernel.org https://git.kernel.org/stable/c/28af028a71371df5fcbf807fd4444bba8d0c33cc
  Patch
• git.kernel.org https://git.kernel.org/stable/c/3bf39fa849ab8ed52abb6715922e6102d3df9f97
  Patch
• git.kernel.org https://git.kernel.org/stable/c/6406d0ce0414b807af5d2a4b781c3f3ee52b8a4d
  Patch