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    Subject[PATCH 3.10 54/85] fs/proc/base.c: fix GPF in /proc/$PID/map_files
    Date
    3.10-stable review patch.  If anyone has any objections, please let me know.

    ------------------

    From: Artem Fetishev <artem_fetishev@epam.com>

    commit 70335abb2689c8cd5df91bf2d95a65649addf50b upstream.

    The expected logic of proc_map_files_get_link() is either to return 0
    and initialize 'path' or return an error and leave 'path' uninitialized.

    By the time dname_to_vma_addr() returns 0 the corresponding vma may have
    already be gone. In this case the path is not initialized but the
    return value is still 0. This results in 'general protection fault'
    inside d_path().

    Steps to reproduce:

    CONFIG_CHECKPOINT_RESTORE=y

    fd = open(...);
    while (1) {
    mmap(fd, ...);
    munmap(fd, ...);
    }

    ls -la /proc/$PID/map_files

    Addresses https://bugzilla.kernel.org/show_bug.cgi?id=68991

    Signed-off-by: Artem Fetishev <artem_fetishev@epam.com>
    Signed-off-by: Aleksandr Terekhov <aleksandr_terekhov@epam.com>
    Reported-by: <wiebittewas@gmail.com>
    Acked-by: Pavel Emelyanov <xemul@parallels.com>
    Acked-by: Cyrill Gorcunov <gorcunov@openvz.org>
    Reviewed-by: "Eric W. Biederman" <ebiederm@xmission.com>
    Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
    Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

    ---
    fs/proc/base.c | 1 +
    1 file changed, 1 insertion(+)

    --- a/fs/proc/base.c
    +++ b/fs/proc/base.c
    @@ -1825,6 +1825,7 @@ static int proc_map_files_get_link(struc
    if (rc)
    goto out_mmput;

    + rc = -ENOENT;
    down_read(&mm->mmap_sem);
    vma = find_exact_vma(mm, vm_start, vm_end);
    if (vma && vma->vm_file) {



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