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authorKent Overstreet <kent.overstreet@gmail.com>2020-12-18 04:07:11 -0500
committerLinus Torvalds <torvalds@linux-foundation.org>2020-12-18 13:37:04 -0800
commit3644e2d2dda78e21edd8f5415b6d7ab03f5f54f3 (patch)
treee9474ee78d90927d36cd1b730d0df405953afde9 /mm
parenta0b96314870f7eff6d15a242cb162dfc46b3c284 (diff)
mm/filemap: fix infinite loop in generic_file_buffered_read()
If iter->count is 0 and iocb->ki_pos is page aligned, this causes nr_pages to be 0. Then in generic_file_buffered_read_get_pages() find_get_pages_contig() returns 0 - because we asked for 0 pages, so we call generic_file_buffered_read_no_cached_page() which attempts to add a page to the page cache, which fails with -EEXIST, and then we loop. Oops... Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com> Reported-by: Jens Axboe <axboe@kernel.dk> Reviewed-by: Jens Axboe <axboe@kernel.dk> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm')
-rw-r--r--mm/filemap.c3
1 files changed, 3 insertions, 0 deletions
diff --git a/mm/filemap.c b/mm/filemap.c
index 7a49bac48aea..5c9d564317a5 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -2453,6 +2453,9 @@ ssize_t generic_file_buffered_read(struct kiocb *iocb,
if (unlikely(iocb->ki_pos >= inode->i_sb->s_maxbytes))
return 0;
+ if (unlikely(!iov_iter_count(iter)))
+ return 0;
+
iov_iter_truncate(iter, inode->i_sb->s_maxbytes);
if (nr_pages > ARRAY_SIZE(pages_onstack))