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40eea803c6
Sasha's report:
> While fuzzing with trinity inside a KVM tools guest running the latest -next
> kernel with the KASAN patchset, I've stumbled on the following spew:
>
> [ 4448.949424] ==================================================================
> [ 4448.951737] AddressSanitizer: user-memory-access on address 0
> [ 4448.952988] Read of size 2 by thread T19638:
> [ 4448.954510] CPU: 28 PID: 19638 Comm: trinity-c76 Not tainted 3.16.0-rc4-next-20140711-sasha-00046-g07d3099-dirty #813
> [ 4448.956823] ffff88046d86ca40 0000000000000000 ffff880082f37e78 ffff880082f37a40
> [ 4448.958233] ffffffffb6e47068 ffff880082f37a68 ffff880082f37a58 ffffffffb242708d
> [ 4448.959552] 0000000000000000 ffff880082f37a88 ffffffffb24255b1 0000000000000000
> [ 4448.961266] Call Trace:
> [ 4448.963158] dump_stack (lib/dump_stack.c:52)
> [ 4448.964244] kasan_report_user_access (mm/kasan/report.c:184)
> [ 4448.965507] __asan_load2 (mm/kasan/kasan.c:352)
> [ 4448.966482] ? netlink_sendmsg (net/netlink/af_netlink.c:2339)
> [ 4448.967541] netlink_sendmsg (net/netlink/af_netlink.c:2339)
> [ 4448.968537] ? get_parent_ip (kernel/sched/core.c:2555)
> [ 4448.970103] sock_sendmsg (net/socket.c:654)
> [ 4448.971584] ? might_fault (mm/memory.c:3741)
> [ 4448.972526] ? might_fault (./arch/x86/include/asm/current.h:14 mm/memory.c:3740)
> [ 4448.973596] ? verify_iovec (net/core/iovec.c:64)
> [ 4448.974522] ___sys_sendmsg (net/socket.c:2096)
> [ 4448.975797] ? put_lock_stats.isra.13 (./arch/x86/include/asm/preempt.h:98 kernel/locking/lockdep.c:254)
> [ 4448.977030] ? lock_release_holdtime (kernel/locking/lockdep.c:273)
> [ 4448.978197] ? lock_release_non_nested (kernel/locking/lockdep.c:3434 (discriminator 1))
> [ 4448.979346] ? check_chain_key (kernel/locking/lockdep.c:2188)
> [ 4448.980535] __sys_sendmmsg (net/socket.c:2181)
> [ 4448.981592] ? trace_hardirqs_on_caller (kernel/locking/lockdep.c:2600)
> [ 4448.982773] ? trace_hardirqs_on (kernel/locking/lockdep.c:2607)
> [ 4448.984458] ? syscall_trace_enter (arch/x86/kernel/ptrace.c:1500 (discriminator 2))
> [ 4448.985621] ? trace_hardirqs_on_caller (kernel/locking/lockdep.c:2600)
> [ 4448.986754] SyS_sendmmsg (net/socket.c:2201)
> [ 4448.987708] tracesys (arch/x86/kernel/entry_64.S:542)
> [ 4448.988929] ==================================================================
This reports means that we've come to netlink_sendmsg() with msg->msg_name == NULL and msg->msg_namelen > 0.
After this report there was no usual "Unable to handle kernel NULL pointer dereference"
and this gave me a clue that address 0 is mapped and contains valid socket address structure in it.
This bug was introduced in
|
||
|---|---|---|
| .. | ||
| datagram.c | ||
| dev_addr_lists.c | ||
| dev_ioctl.c | ||
| dev.c | ||
| drop_monitor.c | ||
| dst.c | ||
| ethtool.c | ||
| fib_rules.c | ||
| filter.c | ||
| flow_dissector.c | ||
| flow.c | ||
| gen_estimator.c | ||
| gen_stats.c | ||
| iovec.c | ||
| link_watch.c | ||
| Makefile | ||
| neighbour.c | ||
| net_namespace.c | ||
| net-procfs.c | ||
| net-sysfs.c | ||
| net-sysfs.h | ||
| net-traces.c | ||
| netclassid_cgroup.c | ||
| netevent.c | ||
| netpoll.c | ||
| netprio_cgroup.c | ||
| pktgen.c | ||
| ptp_classifier.c | ||
| request_sock.c | ||
| rtnetlink.c | ||
| scm.c | ||
| secure_seq.c | ||
| skbuff.c | ||
| sock_diag.c | ||
| sock.c | ||
| stream.c | ||
| sysctl_net_core.c | ||
| timestamping.c | ||
| tso.c | ||
| user_dma.c | ||
| utils.c | ||