mm, fs: check for fatal signals in do_generic_file_read()

commit 5abf186a30a89d5b9c18a6bf93a2c192c9fd52f6 upstream.

do_generic_file_read() can be told to perform a large request from
userspace.  If the system is under OOM and the reading task is the OOM
victim then it has an access to memory reserves and finishing the full
request can lead to the full memory depletion which is dangerous.  Make
sure we rather go with a short read and allow the killed task to
terminate.

Link: http://lkml.kernel.org/r/20170201092706.9966-3-mhocko@kernel.org
Signed-off-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: <stable@vger.kernel.org>
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>

diff --git a/mm/filemap.c b/mm/filemap.c
index 779801092ef1bd28711571c73d24f24f1e7247da..d8d7df82c69a9acf977e08bd07b3f5d8f7f1a53e 100644 (file)
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -1703,6 +1703,11 @@ static ssize_t do_generic_file_read(struct file *filp, loff_t *ppos,
 
                cond_resched();
 find_page:
+               if (fatal_signal_pending(current)) {
+                       error = -EINTR;
+                       goto out;
+               }
+
                page = find_get_page(mapping, index);
                if (!page) {
                        page_cache_sync_readahead(mapping,