The patch titled
Subject: ocfs2: fix uninitialized value in ocfs2_file_read_iter()
has been added to the -mm mm-nonmm-unstable branch. Its filename is
ocfs2-fix-uninitialized-value-in-ocfs2_file_read_iter.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/ocfs2-fix-uninitialized-value-in-ocfs2_file_read_iter.patch
This patch will later appear in the mm-nonmm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: Dmitry Antipov <dmantipov@xxxxxxxxx>
Subject: ocfs2: fix uninitialized value in ocfs2_file_read_iter()
Date: Tue, 29 Oct 2024 12:17:36 +0300
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@xxxxxxxxx
Fixes: 7cdfc3a1c397 ("ocfs2: Remember rw lock level during direct io")
Signed-off-by: Dmitry Antipov <dmantipov@xxxxxxxxx>
Reported-by: syzbot+a73e253cca4f0230a5a5@xxxxxxxxxxxxxxxxxxxxxxxxx
Closes: https://syzkaller.appspot.com/bug?extid=a73e253cca4f0230a5a5
Cc: Mark Fasheh <mark@xxxxxxxxxx>
Cc: Joel Becker <jlbec@xxxxxxxxxxxx>
Cc: Junxiao Bi <junxiao.bi@xxxxxxxxxx>
Cc: Joseph Qi <jiangqi903@xxxxxxxxx>
Cc: Changwei Ge <gechangwei@xxxxxxx>
Cc: Gang He <ghe@xxxxxxxx>
Cc: Jun Piao <piaojun@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/ocfs2/aops.h | 2 ++
fs/ocfs2/file.c | 4 ++++
2 files changed, 6 insertions(+)
--- a/fs/ocfs2/aops.h~ocfs2-fix-uninitialized-value-in-ocfs2_file_read_iter
+++ a/fs/ocfs2/aops.h
@@ -70,6 +70,8 @@ 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) \
--- a/fs/ocfs2/file.c~ocfs2-fix-uninitialized-value-in-ocfs2_file_read_iter
+++ a/fs/ocfs2/file.c
@@ -2398,6 +2398,8 @@ static ssize_t ocfs2_file_write_iter(str
} else
inode_lock(inode);
+ ocfs2_iocb_init_rw_locked(iocb);
+
/*
* Concurrent O_DIRECT writes are allowed with
* mount_option "coherency=buffered".
@@ -2544,6 +2546,8 @@ static ssize_t ocfs2_file_read_iter(stru
if (!direct_io && nowait)
return -EOPNOTSUPP;
+ ocfs2_iocb_init_rw_locked(iocb);
+
/*
* buffered reads protect themselves in ->read_folio(). O_DIRECT reads
* need locks to protect pending reads from racing with truncate.
_
Patches currently in -mm which might be from dmantipov@xxxxxxxxx are
ocfs2-fix-uninitialized-value-in-ocfs2_file_read_iter.patch
