1. 22 Oct, 2016 37 commits
  2. 20 Oct, 2016 3 commits
    • Greg Kroah-Hartman's avatar
      Linux 4.8.3 · 1888926e
      Greg Kroah-Hartman authored
      1888926e
    • Linus Torvalds's avatar
      mm: remove gup_flags FOLL_WRITE games from __get_user_pages() · 89eeba15
      Linus Torvalds authored
      commit 19be0eaf upstream.
      
      This is an ancient bug that was actually attempted to be fixed once
      (badly) by me eleven years ago in commit 4ceb5db9 ("Fix
      get_user_pages() race for write access") but that was then undone due to
      problems on s390 by commit f33ea7f4 ("fix get_user_pages bug").
      
      In the meantime, the s390 situation has long been fixed, and we can now
      fix it by checking the pte_dirty() bit properly (and do it better).  The
      s390 dirty bit was implemented in abf09bed ("s390/mm: implement
      software dirty bits") which made it into v3.9.  Earlier kernels will
      have to look at the page state itself.
      
      Also, the VM has become more scalable, and what used a purely
      theoretical race back then has become easier to trigger.
      
      To fix it, we introduce a new internal FOLL_COW flag to mark the "yes,
      we already did a COW" rather than play racy games with FOLL_WRITE that
      is very fundamental, and then use the pte dirty flag to validate that
      the FOLL_COW flag is still valid.
      Reported-and-tested-by: default avatarPhil "not Paul" Oester <kernel@linuxace.com>
      Acked-by: default avatarHugh Dickins <hughd@google.com>
      Reviewed-by: default avatarMichal Hocko <mhocko@suse.com>
      Cc: Andy Lutomirski <luto@kernel.org>
      Cc: Kees Cook <keescook@chromium.org>
      Cc: Oleg Nesterov <oleg@redhat.com>
      Cc: Willy Tarreau <w@1wt.eu>
      Cc: Nick Piggin <npiggin@gmail.com>
      Cc: Greg Thelen <gthelen@google.com>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      89eeba15
    • Artem Savkov's avatar
      Make __xfs_xattr_put_listen preperly report errors. · 0312017c
      Artem Savkov authored
      commit 791cc43b upstream.
      
      Commit 2a6fba6d "xfs: only return -errno or success from attr ->put_listent"
      changes the returnvalue of __xfs_xattr_put_listen to 0 in case when there is
      insufficient space in the buffer assuming that setting context->count to -1
      would be enough, but all of the ->put_listent callers only check seen_enough.
      This results in a failed assertion:
      XFS: Assertion failed: context->count >= 0, file: fs/xfs/xfs_xattr.c, line: 175
      in insufficient buffer size case.
      
      This is only reproducible with at least 2 xattrs and only when the buffer
      gets depleted before the last one.
      
      Furthermore if buffersize is such that it is enough to hold the last xattr's
      name, but not enough to hold the sum of preceeding xattr names listxattr won't
      fail with ERANGE, but will suceed returning last xattr's name without the
      first character. The first character end's up overwriting data stored at
      (context->alist - 1).
      Signed-off-by: default avatarArtem Savkov <asavkov@redhat.com>
      Reviewed-by: default avatarDave Chinner <dchinner@redhat.com>
      Signed-off-by: default avatarDave Chinner <david@fromorbit.com>
      Cc: Eric Sandeen <sandeen@redhat.com>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      0312017c