mainlining shenanigans
0ff50e83b5
rtnl_fdb_dump() failed to check the result of nlmsg_parse(), which led to contents of |ifm| being uninitialized because nlh->nlmsglen was too small to accommodate |ifm|. The uninitialized data may affect some branches and result in unwanted effects, although kernel data doesn't seem to leak to the userspace directly. The bug has been detected with KMSAN and syzkaller. For the record, here is the KMSAN report: ================================================================== BUG: KMSAN: use of unitialized memory in rtnl_fdb_dump+0x5dc/0x1000 CPU: 0 PID: 1039 Comm: probe Not tainted 4.11.0-rc5+ #2727 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:16 dump_stack+0x143/0x1b0 lib/dump_stack.c:52 kmsan_report+0x12a/0x180 mm/kmsan/kmsan.c:1007 __kmsan_warning_32+0x66/0xb0 mm/kmsan/kmsan_instr.c:491 rtnl_fdb_dump+0x5dc/0x1000 net/core/rtnetlink.c:3230 netlink_dump+0x84f/0x1190 net/netlink/af_netlink.c:2168 __netlink_dump_start+0xc97/0xe50 net/netlink/af_netlink.c:2258 netlink_dump_start ./include/linux/netlink.h:165 rtnetlink_rcv_msg+0xae9/0xb40 net/core/rtnetlink.c:4094 netlink_rcv_skb+0x339/0x5a0 net/netlink/af_netlink.c:2339 rtnetlink_rcv+0x83/0xa0 net/core/rtnetlink.c:4110 netlink_unicast_kernel net/netlink/af_netlink.c:1272 netlink_unicast+0x13b7/0x1480 net/netlink/af_netlink.c:1298 netlink_sendmsg+0x10b8/0x10f0 net/netlink/af_netlink.c:1844 sock_sendmsg_nosec net/socket.c:633 sock_sendmsg net/socket.c:643 ___sys_sendmsg+0xd4b/0x10f0 net/socket.c:1997 __sys_sendmsg net/socket.c:2031 SYSC_sendmsg+0x2c6/0x3f0 net/socket.c:2042 SyS_sendmsg+0x87/0xb0 net/socket.c:2038 do_syscall_64+0x102/0x150 arch/x86/entry/common.c:285 entry_SYSCALL64_slow_path+0x25/0x25 arch/x86/entry/entry_64.S:246 RIP: 0033:0x401300 RSP: 002b:00007ffc3b0e6d58 EFLAGS: 00000246 ORIG_RAX: 000000000000002e RAX: ffffffffffffffda RBX: 00000000004002b0 RCX: 0000000000401300 RDX: 0000000000000000 RSI: 00007ffc3b0e6d80 RDI: 0000000000000003 RBP: 00007ffc3b0e6e00 R08: 000000000000000b R09: 0000000000000004 R10: 000000000000000d R11: 0000000000000246 R12: 0000000000000000 R13: 00000000004065a0 R14: 0000000000406630 R15: 0000000000000000 origin: 000000008fe00056 save_stack_trace+0x59/0x60 arch/x86/kernel/stacktrace.c:59 kmsan_save_stack_with_flags mm/kmsan/kmsan.c:352 kmsan_internal_poison_shadow+0xb1/0x1a0 mm/kmsan/kmsan.c:247 kmsan_poison_shadow+0x6d/0xc0 mm/kmsan/kmsan.c:260 slab_alloc_node mm/slub.c:2743 __kmalloc_node_track_caller+0x1f4/0x390 mm/slub.c:4349 __kmalloc_reserve net/core/skbuff.c:138 __alloc_skb+0x2cd/0x740 net/core/skbuff.c:231 alloc_skb ./include/linux/skbuff.h:933 netlink_alloc_large_skb net/netlink/af_netlink.c:1144 netlink_sendmsg+0x934/0x10f0 net/netlink/af_netlink.c:1819 sock_sendmsg_nosec net/socket.c:633 sock_sendmsg net/socket.c:643 ___sys_sendmsg+0xd4b/0x10f0 net/socket.c:1997 __sys_sendmsg net/socket.c:2031 SYSC_sendmsg+0x2c6/0x3f0 net/socket.c:2042 SyS_sendmsg+0x87/0xb0 net/socket.c:2038 do_syscall_64+0x102/0x150 arch/x86/entry/common.c:285 return_from_SYSCALL_64+0x0/0x6a arch/x86/entry/entry_64.S:246 ================================================================== and the reproducer: ================================================================== #include <sys/socket.h> #include <net/if_arp.h> #include <linux/netlink.h> #include <stdint.h> int main() { int sock = socket(PF_NETLINK, SOCK_DGRAM | SOCK_NONBLOCK, 0); struct msghdr msg; memset(&msg, 0, sizeof(msg)); char nlmsg_buf[32]; memset(nlmsg_buf, 0, sizeof(nlmsg_buf)); struct nlmsghdr *nlmsg = nlmsg_buf; nlmsg->nlmsg_len = 0x11; nlmsg->nlmsg_type = 0x1e; // RTM_NEWROUTE = RTM_BASE + 0x0e // type = 0x0e = 1110b // kind = 2 nlmsg->nlmsg_flags = 0x101; // NLM_F_ROOT | NLM_F_REQUEST nlmsg->nlmsg_seq = 0; nlmsg->nlmsg_pid = 0; nlmsg_buf[16] = (char)7; struct iovec iov; iov.iov_base = nlmsg_buf; iov.iov_len = 17; msg.msg_iov = &iov; msg.msg_iovlen = 1; sendmsg(sock, &msg, 0); return 0; } ================================================================== Signed-off-by: Alexander Potapenko <glider@google.com> Signed-off-by: David S. Miller <davem@davemloft.net> |
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| block | ||
| certs | ||
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| Documentation | ||
| drivers | ||
| firmware | ||
| fs | ||
| include | ||
| init | ||
| ipc | ||
| kernel | ||
| lib | ||
| mm | ||
| net | ||
| samples | ||
| scripts | ||
| security | ||
| sound | ||
| tools | ||
| usr | ||
| virt | ||
| .cocciconfig | ||
| .get_maintainer.ignore | ||
| .gitattributes | ||
| .gitignore | ||
| .mailmap | ||
| COPYING | ||
| CREDITS | ||
| Kbuild | ||
| Kconfig | ||
| MAINTAINERS | ||
| Makefile | ||
| README | ||
Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. There are various text files in the Documentation/ subdirectory, several of them using the Restructured Text markup notation. See Documentation/00-INDEX for a list of what is contained in each file. Please read the Documentation/process/changes.rst file, as it contains the requirements for building and running the kernel, and information about the problems which may result by upgrading your kernel.