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| author | Kent Overstreet <kent.overstreet@gmail.com> | 2020-12-18 04:07:11 -0500 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2020-12-18 13:37:04 -0800 |
| commit | 3644e2d2dda78e21edd8f5415b6d7ab03f5f54f3 (patch) | |
| tree | e9474ee78d90927d36cd1b730d0df405953afde9 | |
| parent | a0b96314870f7eff6d15a242cb162dfc46b3c284 (diff) | |
| download | linux-3644e2d2dda78e21edd8f5415b6d7ab03f5f54f3.tar.gz | |
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>
| -rw-r--r-- | mm/filemap.c | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/mm/filemap.c b/mm/filemap.c index 7a49bac48aea55..5c9d564317a5c5 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)) |