Commit 70335abb authored by Artem Fetishev's avatar Artem Fetishev Committed by Linus Torvalds

fs/proc/base.c: fix GPF in /proc/$PID/map_files

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=68991Signed-off-by: default avatarArtem Fetishev <artem_fetishev@epam.com>
Signed-off-by: default avatarAleksandr Terekhov <aleksandr_terekhov@epam.com>
Reported-by: <wiebittewas@gmail.com>
Acked-by: default avatarPavel Emelyanov <xemul@parallels.com>
Acked-by: default avatarCyrill Gorcunov <gorcunov@openvz.org>
Reviewed-by: default avatar"Eric W. Biederman" <ebiederm@xmission.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 2af120bc
...@@ -1824,6 +1824,7 @@ static int proc_map_files_get_link(struct dentry *dentry, struct path *path) ...@@ -1824,6 +1824,7 @@ static int proc_map_files_get_link(struct dentry *dentry, struct path *path)
if (rc) if (rc)
goto out_mmput; goto out_mmput;
rc = -ENOENT;
down_read(&mm->mmap_sem); down_read(&mm->mmap_sem);
vma = find_exact_vma(mm, vm_start, vm_end); vma = find_exact_vma(mm, vm_start, vm_end);
if (vma && vma->vm_file) { if (vma && vma->vm_file) {
......
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