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| author | Peter Xu <peterx@redhat.com> | 2020-04-07 21:40:09 -0400 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2020-04-07 19:34:31 -0700 |
| commit | ba841078cd0557b43b59c63f5c048b12168f0db2 (patch) | |
| tree | 3697b4a407d713c5aca73827a2d34574865508e8 /mm | |
| parent | 63bef48fd6c9d3f1ba4f0e23b4da1e007db6a3c0 (diff) | |
| download | linux-stable-ba841078cd0557b43b59c63f5c048b12168f0db2.tar.gz linux-stable-ba841078cd0557b43b59c63f5c048b12168f0db2.tar.bz2 linux-stable-ba841078cd0557b43b59c63f5c048b12168f0db2.zip | |
mm/mempolicy: Allow lookup_node() to handle fatal signal
lookup_node() uses gup to pin the page and get node information. It
checks against ret>=0 assuming the page will be filled in. However it's
also possible that gup will return zero, for example, when the thread is
quickly killed with a fatal signal. Teach lookup_node() to gracefully
return an error -EFAULT if it happens.
Meanwhile, initialize "page" to NULL to avoid potential risk of
exploiting the pointer.
Fixes: 4426e945df58 ("mm/gup: allow VM_FAULT_RETRY for multiple times")
Reported-by: syzbot+693dc11fcb53120b5559@syzkaller.appspotmail.com
Signed-off-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm')
| -rw-r--r-- | mm/mempolicy.c | 7 |
1 files changed, 5 insertions, 2 deletions
diff --git a/mm/mempolicy.c b/mm/mempolicy.c index b4a039d779b0..fb678a7254f0 100644 --- a/mm/mempolicy.c +++ b/mm/mempolicy.c @@ -896,12 +896,15 @@ static void get_policy_nodemask(struct mempolicy *p, nodemask_t *nodes) static int lookup_node(struct mm_struct *mm, unsigned long addr) { - struct page *p; + struct page *p = NULL; int err; int locked = 1; err = get_user_pages_locked(addr & PAGE_MASK, 1, 0, &p, &locked); - if (err >= 0) { + if (err == 0) { + /* E.g. GUP interrupted by fatal signal */ + err = -EFAULT; + } else if (err > 0) { err = page_to_nid(p); put_page(p); } |