mirror of
https://github.com/Divested-Mobile/DivestOS-Build.git
synced 2024-12-10 08:24:20 -05:00
62 lines
2.2 KiB
Diff
62 lines
2.2 KiB
Diff
From 3ca8138f014a913f98e6ef40e939868e1e9ea876 Mon Sep 17 00:00:00 2001
|
|
From: Roman Gushchin <klamm@yandex-team.ru>
|
|
Date: Mon, 12 Oct 2015 16:33:44 +0300
|
|
Subject: fuse: break infinite loop in fuse_fill_write_pages()
|
|
|
|
I got a report about unkillable task eating CPU. Further
|
|
investigation shows, that the problem is in the fuse_fill_write_pages()
|
|
function. If iov's first segment has zero length, we get an infinite
|
|
loop, because we never reach iov_iter_advance() call.
|
|
|
|
Fix this by calling iov_iter_advance() before repeating an attempt to
|
|
copy data from userspace.
|
|
|
|
A similar problem is described in 124d3b7041f ("fix writev regression:
|
|
pan hanging unkillable and un-straceable"). If zero-length segmend
|
|
is followed by segment with invalid address,
|
|
iov_iter_fault_in_readable() checks only first segment (zero-length),
|
|
iov_iter_copy_from_user_atomic() skips it, fails at second and
|
|
returns zero -> goto again without skipping zero-length segment.
|
|
|
|
Patch calls iov_iter_advance() before goto again: we'll skip zero-length
|
|
segment at second iteraction and iov_iter_fault_in_readable() will detect
|
|
invalid address.
|
|
|
|
Special thanks to Konstantin Khlebnikov, who helped a lot with the commit
|
|
description.
|
|
|
|
Cc: Andrew Morton <akpm@linux-foundation.org>
|
|
Cc: Maxim Patlasov <mpatlasov@parallels.com>
|
|
Cc: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
|
|
Signed-off-by: Roman Gushchin <klamm@yandex-team.ru>
|
|
Signed-off-by: Miklos Szeredi <miklos@szeredi.hu>
|
|
Fixes: ea9b9907b82a ("fuse: implement perform_write")
|
|
Cc: <stable@vger.kernel.org>
|
|
---
|
|
fs/fuse/file.c | 2 +-
|
|
1 file changed, 1 insertion(+), 1 deletion(-)
|
|
|
|
diff --git a/fs/fuse/file.c b/fs/fuse/file.c
|
|
index f523f2f..195476a 100644
|
|
--- a/fs/fuse/file.c
|
|
+++ b/fs/fuse/file.c
|
|
@@ -1049,6 +1049,7 @@ static ssize_t fuse_fill_write_pages(struct fuse_req *req,
|
|
tmp = iov_iter_copy_from_user_atomic(page, ii, offset, bytes);
|
|
flush_dcache_page(page);
|
|
|
|
+ iov_iter_advance(ii, tmp);
|
|
if (!tmp) {
|
|
unlock_page(page);
|
|
page_cache_release(page);
|
|
@@ -1061,7 +1062,6 @@ static ssize_t fuse_fill_write_pages(struct fuse_req *req,
|
|
req->page_descs[req->num_pages].length = tmp;
|
|
req->num_pages++;
|
|
|
|
- iov_iter_advance(ii, tmp);
|
|
count += tmp;
|
|
pos += tmp;
|
|
offset += tmp;
|
|
--
|
|
cgit v1.1
|
|
|