Messages in this thread Patch in this message | | | From | Shaohua Li <> | Subject | [PATCH] FS: fix stack-out-of-bounds wanning | Date | Mon, 8 May 2017 16:42:50 -0700 |
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I'm seeing below with lastet upstream. Commit 5ecda13(generic_file_read_iter(): make use of iov_iter_revert()) directly pass iter to ->direct_IO(), ->direct_io already advances count bytes but return -EIOCBQUEUED. In this case, count is bigger than iov_iter_count(iter). We really want to revert count - iov_iter_count(iter) instead of the opposite.
[ 5754.726656] ================================================================== [ 5754.727246] BUG: KASAN: stack-out-of-bounds in iov_iter_revert+0x14b/0x450 [ 5754.727708] Read of size 8 at addr ffff880115247cb8 by task fio/1563 [ 5754.728502] CPU: 1 PID: 1563 Comm: fio Not tainted 4.11.0+ #1394 [ 5754.728506] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.9.1-5.el7_3.2 04/01/2014 [ 5754.728509] Call Trace: [ 5754.728520] dump_stack+0x67/0x92 [ 5754.728529] print_address_description+0xd9/0x270 [ 5754.728536] ? iov_iter_revert+0x14b/0x450 [ 5754.728542] kasan_report+0x265/0x350 [ 5754.728551] __asan_load8+0x5e/0x70 [ 5754.728555] iov_iter_revert+0x14b/0x450 [ 5754.728562] ? filemap_check_errors+0x41/0x80 [ 5754.728572] generic_file_read_iter+0xb16/0x1030 [ 5754.728578] ? mark_held_locks+0x23/0xc0 [ 5754.728584] ? depot_save_stack+0x1d2/0x470 [ 5754.728592] ? _raw_spin_unlock_irqrestore+0x36/0x50 [ 5754.728599] ? trace_hardirqs_on_caller+0x186/0x260 [ 5754.728604] ? trace_hardirqs_on+0xd/0x10 [ 5754.728612] ? depot_save_stack+0x34a/0x470 [ 5754.728622] ? generic_file_write_iter+0x2b0/0x2b0 [ 5754.728627] ? mark_lock+0x6d/0x850 [ 5754.728632] ? save_stack_trace+0x1b/0x20 [ 5754.728636] ? save_stack+0x46/0xd0 [ 5754.728641] ? mark_lock+0x6d/0x850 [ 5754.728649] ? import_single_range+0xfb/0x140 [ 5754.728685] blkdev_read_iter+0x7d/0x90 [ 5754.728693] aio_read+0x1be/0x200
FIx: 5ecda13(generic_file_read_iter(): make use of iov_iter_revert()) Cc: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Shaohua Li <shli@fb.com> --- mm/filemap.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/mm/filemap.c b/mm/filemap.c index 681da61..df227638 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -2050,7 +2050,7 @@ generic_file_read_iter(struct kiocb *iocb, struct iov_iter *iter) iocb->ki_pos += retval; count -= retval; } - iov_iter_revert(iter, iov_iter_count(iter) - count); + iov_iter_revert(iter, count - iov_iter_count(iter)); /* * Btrfs can have a short DIO read if we encounter -- 2.9.3
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