diff options
| author | Miklos Szeredi <mszeredi@redhat.com> | 2020-09-18 10:36:50 +0200 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2020-11-05 11:06:52 +0100 |
| commit | c1d98a59f1f5d4051ca1ae301709b2efec785ecb (patch) | |
| tree | 0d17d42505549a349e9cab6f3130d9364db10ba9 /fs | |
| parent | d23fef2d05fba40d2fbb31a7e068a5eb543ec228 (diff) | |
fuse: fix page dereference after free
commit d78092e4937de9ce55edcb4ee4c5e3c707be0190 upstream.
After unlock_request() pages from the ap->pages[] array may be put (e.g. by
aborting the connection) and the pages can be freed.
Prevent use after free by grabbing a reference to the page before calling
unlock_request().
The original patch was created by Pradeep P V K.
Reported-by: Pradeep P V K <ppvk@codeaurora.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'fs')
| -rw-r--r-- | fs/fuse/dev.c | 28 |
1 files changed, 18 insertions, 10 deletions
diff --git a/fs/fuse/dev.c b/fs/fuse/dev.c index 1b9c4c19bed2..cfc19140f2a0 100644 --- a/fs/fuse/dev.c +++ b/fs/fuse/dev.c @@ -845,15 +845,16 @@ static int fuse_try_move_page(struct fuse_copy_state *cs, struct page **pagep) struct page *newpage; struct pipe_buffer *buf = cs->pipebufs; + get_page(oldpage); err = unlock_request(cs->req); if (err) - return err; + goto out_put_old; fuse_copy_finish(cs); err = pipe_buf_confirm(cs->pipe, buf); if (err) - return err; + goto out_put_old; BUG_ON(!cs->nr_segs); cs->currbuf = buf; @@ -893,7 +894,7 @@ static int fuse_try_move_page(struct fuse_copy_state *cs, struct page **pagep) err = replace_page_cache_page(oldpage, newpage, GFP_KERNEL); if (err) { unlock_page(newpage); - return err; + goto out_put_old; } get_page(newpage); @@ -912,14 +913,19 @@ static int fuse_try_move_page(struct fuse_copy_state *cs, struct page **pagep) if (err) { unlock_page(newpage); put_page(newpage); - return err; + goto out_put_old; } unlock_page(oldpage); + /* Drop ref for ap->pages[] array */ put_page(oldpage); cs->len = 0; - return 0; + err = 0; +out_put_old: + /* Drop ref obtained in this function */ + put_page(oldpage); + return err; out_fallback_unlock: unlock_page(newpage); @@ -928,10 +934,10 @@ out_fallback: cs->offset = buf->offset; err = lock_request(cs->req); - if (err) - return err; + if (!err) + err = 1; - return 1; + goto out_put_old; } static int fuse_ref_page(struct fuse_copy_state *cs, struct page *page, @@ -943,14 +949,16 @@ static int fuse_ref_page(struct fuse_copy_state *cs, struct page *page, if (cs->nr_segs == cs->pipe->buffers) return -EIO; + get_page(page); err = unlock_request(cs->req); - if (err) + if (err) { + put_page(page); return err; + } fuse_copy_finish(cs); buf = cs->pipebufs; - get_page(page); buf->page = page; buf->offset = offset; buf->len = count; |