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    Subject[PATCH 5.4 116/191] tracing: Avoid memory leak in process_system_preds()
    Date
    From: Keita Suzuki <keitasuzuki.park@sslab.ics.keio.ac.jp>

    commit 79e65c27f09683fbb50c33acab395d0ddf5302d2 upstream.

    When failing in the allocation of filter_item, process_system_preds()
    goes to fail_mem, where the allocated filter is freed.

    However, this leads to memory leak of filter->filter_string and
    filter->prog, which is allocated before and in process_preds().
    This bug has been detected by kmemleak as well.

    Fix this by changing kfree to __free_fiter.

    unreferenced object 0xffff8880658007c0 (size 32):
    comm "bash", pid 579, jiffies 4295096372 (age 17.752s)
    hex dump (first 32 bytes):
    63 6f 6d 6d 6f 6e 5f 70 69 64 20 20 3e 20 31 30 common_pid > 10
    00 00 00 00 00 00 00 00 65 73 00 00 00 00 00 00 ........es......
    backtrace:
    [<0000000067441602>] kstrdup+0x2d/0x60
    [<00000000141cf7b7>] apply_subsystem_event_filter+0x378/0x932
    [<000000009ca32334>] subsystem_filter_write+0x5a/0x90
    [<0000000072da2bee>] vfs_write+0xe1/0x240
    [<000000004f14f473>] ksys_write+0xb4/0x150
    [<00000000a968b4a0>] do_syscall_64+0x6d/0x1e0
    [<000000001a189f40>] entry_SYSCALL_64_after_hwframe+0x44/0xa9
    unreferenced object 0xffff888060c22d00 (size 64):
    comm "bash", pid 579, jiffies 4295096372 (age 17.752s)
    hex dump (first 32 bytes):
    01 00 00 00 00 00 00 00 00 e8 d7 41 80 88 ff ff ...........A....
    01 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
    backtrace:
    [<00000000b8c1b109>] process_preds+0x243/0x1820
    [<000000003972c7f0>] apply_subsystem_event_filter+0x3be/0x932
    [<000000009ca32334>] subsystem_filter_write+0x5a/0x90
    [<0000000072da2bee>] vfs_write+0xe1/0x240
    [<000000004f14f473>] ksys_write+0xb4/0x150
    [<00000000a968b4a0>] do_syscall_64+0x6d/0x1e0
    [<000000001a189f40>] entry_SYSCALL_64_after_hwframe+0x44/0xa9
    unreferenced object 0xffff888041d7e800 (size 512):
    comm "bash", pid 579, jiffies 4295096372 (age 17.752s)
    hex dump (first 32 bytes):
    70 bc 85 97 ff ff ff ff 0a 00 00 00 00 00 00 00 p...............
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
    backtrace:
    [<000000001e04af34>] process_preds+0x71a/0x1820
    [<000000003972c7f0>] apply_subsystem_event_filter+0x3be/0x932
    [<000000009ca32334>] subsystem_filter_write+0x5a/0x90
    [<0000000072da2bee>] vfs_write+0xe1/0x240
    [<000000004f14f473>] ksys_write+0xb4/0x150
    [<00000000a968b4a0>] do_syscall_64+0x6d/0x1e0
    [<000000001a189f40>] entry_SYSCALL_64_after_hwframe+0x44/0xa9

    Link: http://lkml.kernel.org/r/20191211091258.11310-1-keitasuzuki.park@sslab.ics.keio.ac.jp

    Cc: Ingo Molnar <mingo@redhat.com>
    Cc: stable@vger.kernel.org
    Fixes: 404a3add43c9c ("tracing: Only add filter list when needed")
    Signed-off-by: Keita Suzuki <keitasuzuki.park@sslab.ics.keio.ac.jp>
    Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

    ---
    kernel/trace/trace_events_filter.c | 2 +-
    1 file changed, 1 insertion(+), 1 deletion(-)

    --- a/kernel/trace/trace_events_filter.c
    +++ b/kernel/trace/trace_events_filter.c
    @@ -1662,7 +1662,7 @@ static int process_system_preds(struct t
    parse_error(pe, FILT_ERR_BAD_SUBSYS_FILTER, 0);
    return -EINVAL;
    fail_mem:
    - kfree(filter);
    + __free_filter(filter);
    /* If any call succeeded, we still need to sync */
    if (!fail)
    tracepoint_synchronize_unregister();

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