linux-kernel - [PATCH 2/3] mm, fs: check for fatal signals in do_generic_file

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Date:   Wed,  1 Feb 2017 10:27:05 +0100
From:   Michal Hocko <mhocko@...nel.org>
To:     Andrew Morton <akpm@...ux-foundation.org>
Cc:     Christoph Hellwig <hch@....de>,
        Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp>,
        Al Viro <viro@...iv.linux.org.uk>, <linux-mm@...ck.org>,
        <linux-fsdevel@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Michal Hocko <mhocko@...e.com>
Subject: [PATCH 2/3] mm, fs: check for fatal signals in do_generic_file_read

From: Michal Hocko <mhocko@...e.com>

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.

Cc: stable
Signed-off-by: Michal Hocko <mhocko@...e.com>
---
 mm/filemap.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/mm/filemap.c b/mm/filemap.c
index 14bddd0d7fa4..2ba46f410c7c 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -1797,6 +1797,11 @@ 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,
-- 
2.11.0