5.4-stable review patch. If anyone has any objections, please let me know.
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From: Dmitry Antipov dmantipov@yandex.ru
[ Upstream commit adc77b19f62d7e80f98400b2fca9d700d2afdd6f ]
Syzbot has reported the following KMSAN splat:
BUG: KMSAN: uninit-value in ocfs2_file_read_iter+0x9a4/0xf80 ocfs2_file_read_iter+0x9a4/0xf80 __io_read+0x8d4/0x20f0 io_read+0x3e/0xf0 io_issue_sqe+0x42b/0x22c0 io_wq_submit_work+0xaf9/0xdc0 io_worker_handle_work+0xd13/0x2110 io_wq_worker+0x447/0x1410 ret_from_fork+0x6f/0x90 ret_from_fork_asm+0x1a/0x30
Uninit was created at: __alloc_pages_noprof+0x9a7/0xe00 alloc_pages_mpol_noprof+0x299/0x990 alloc_pages_noprof+0x1bf/0x1e0 allocate_slab+0x33a/0x1250 ___slab_alloc+0x12ef/0x35e0 kmem_cache_alloc_bulk_noprof+0x486/0x1330 __io_alloc_req_refill+0x84/0x560 io_submit_sqes+0x172f/0x2f30 __se_sys_io_uring_enter+0x406/0x41c0 __x64_sys_io_uring_enter+0x11f/0x1a0 x64_sys_call+0x2b54/0x3ba0 do_syscall_64+0xcd/0x1e0 entry_SYSCALL_64_after_hwframe+0x77/0x7f
Since an instance of 'struct kiocb' may be passed from the block layer with 'private' field uninitialized, introduce 'ocfs2_iocb_init_rw_locked()' and use it from where 'ocfs2_dio_end_io()' might take care, i.e. in 'ocfs2_file_read_iter()' and 'ocfs2_file_write_iter()'.
Link: https://lkml.kernel.org/r/20241029091736.1501946-1-dmantipov@yandex.ru Fixes: 7cdfc3a1c397 ("ocfs2: Remember rw lock level during direct io") Signed-off-by: Dmitry Antipov dmantipov@yandex.ru Reported-by: syzbot+a73e253cca4f0230a5a5@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=a73e253cca4f0230a5a5 Cc: Mark Fasheh mark@fasheh.com Cc: Joel Becker jlbec@evilplan.org Cc: Junxiao Bi junxiao.bi@oracle.com Cc: Joseph Qi jiangqi903@gmail.com Cc: Changwei Ge gechangwei@live.cn Cc: Jun Piao piaojun@huawei.com Signed-off-by: Andrew Morton akpm@linux-foundation.org Signed-off-by: Sasha Levin sashal@kernel.org --- fs/ocfs2/aops.h | 2 ++ fs/ocfs2/file.c | 4 ++++ 2 files changed, 6 insertions(+)
diff --git a/fs/ocfs2/aops.h b/fs/ocfs2/aops.h index 70ed4382750d5..5b129ae9c3d22 100644 --- a/fs/ocfs2/aops.h +++ b/fs/ocfs2/aops.h @@ -72,6 +72,8 @@ enum ocfs2_iocb_lock_bits { OCFS2_IOCB_NUM_LOCKS };
+#define ocfs2_iocb_init_rw_locked(iocb) \ + (iocb->private = NULL) #define ocfs2_iocb_clear_rw_locked(iocb) \ clear_bit(OCFS2_IOCB_RW_LOCK, (unsigned long *)&iocb->private) #define ocfs2_iocb_rw_locked_level(iocb) \ diff --git a/fs/ocfs2/file.c b/fs/ocfs2/file.c index 3bbeea2e60f70..54b843f5b73f5 100644 --- a/fs/ocfs2/file.c +++ b/fs/ocfs2/file.c @@ -2401,6 +2401,8 @@ static ssize_t ocfs2_file_write_iter(struct kiocb *iocb, } else inode_lock(inode);
+ ocfs2_iocb_init_rw_locked(iocb); + /* * Concurrent O_DIRECT writes are allowed with * mount_option "coherency=buffered". @@ -2547,6 +2549,8 @@ static ssize_t ocfs2_file_read_iter(struct kiocb *iocb, if (!direct_io && nowait) return -EOPNOTSUPP;
+ ocfs2_iocb_init_rw_locked(iocb); + /* * buffered reads protect themselves in ->readpage(). O_DIRECT reads * need locks to protect pending reads from racing with truncate.