From: Chao Yu <yuchao0@huawei.com>
To: <jaegeuk@kernel.org>
Cc: <kt0755@gmail.com>, <dan.carpenter@oracle.com>,
<ebiggers@google.com>, Chao Yu <yuchao0@huawei.com>,
<linux-f2fs-devel@lists.sourceforge.net>,
<linux-kernel@vger.kernel.org>, <chao@kernel.org>
Subject: [PATCH] f2fs: fix to initialize variable to avoid UBSAN/smatch warning
Date: Wed, 16 Jan 2019 09:51:28 +0800 [thread overview]
Message-ID: <20190116015128.112292-1-yuchao0@huawei.com> (raw)
As Dan Carpenter as below:
The patch df634f444ee9: "f2fs: use rb_*_cached friends" from Oct 4,
2018, leads to the following static checker warning:
fs/f2fs/extent_cache.c:606 f2fs_update_extent_tree_range()
error: uninitialized symbol 'leftmost'.
And also Eric Biggers, and Kyungtae Kim reported, there is an UBSAN
warning described as below:
We report a bug in linux-4.20.2: "UBSAN: Undefined behaviour in
fs/f2fs/extent_cache.c"
kernel config: https://kt0755.github.io/etc/config_v4.20_stable
repro: https://kt0755.github.io/etc/repro.4a3e7.c (f2fs is mounted on
/mnt/f2fs/)
This arose in f2fs_update_extent_tree_range (fs/f2fs/extent_cache.c:605).
It seems that, for some reason, its last argument became "24"
although that was supposed to be bool type.
=========================================
UBSAN: Undefined behaviour in fs/f2fs/extent_cache.c:605:4
load of value 24 is not a valid value for type '_Bool'
CPU: 0 PID: 6774 Comm: syz-executor5 Not tainted 4.20.2 #1
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011
Call Trace:
__dump_stack lib/dump_stack.c:77 [inline]
dump_stack+0xb1/0x118 lib/dump_stack.c:113
ubsan_epilogue+0x12/0x94 lib/ubsan.c:159
__ubsan_handle_load_invalid_value+0x17a/0x1be lib/ubsan.c:457
f2fs_update_extent_tree_range+0x1d4a/0x1d50 fs/f2fs/extent_cache.c:605
f2fs_update_extent_cache+0x2b6/0x350 fs/f2fs/extent_cache.c:804
f2fs_update_data_blkaddr+0x61/0x70 fs/f2fs/data.c:656
f2fs_outplace_write_data+0x1d6/0x4b0 fs/f2fs/segment.c:3140
f2fs_convert_inline_page+0x86d/0x2060 fs/f2fs/inline.c:163
f2fs_convert_inline_inode+0x6b5/0xad0 fs/f2fs/inline.c:208
f2fs_preallocate_blocks+0x78b/0xb00 fs/f2fs/data.c:982
f2fs_file_write_iter+0x31b/0xf40 fs/f2fs/file.c:3062
call_write_iter include/linux/fs.h:1857 [inline]
new_sync_write fs/read_write.c:474 [inline]
__vfs_write+0x538/0x6e0 fs/read_write.c:487
vfs_write+0x1b3/0x520 fs/read_write.c:549
ksys_write+0xde/0x1c0 fs/read_write.c:598
__do_sys_write fs/read_write.c:610 [inline]
__se_sys_write fs/read_write.c:607 [inline]
__x64_sys_write+0x7e/0xc0 fs/read_write.c:607
do_syscall_64+0xbe/0x4f0 arch/x86/entry/common.c:290
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x4497b9
Code: e8 8c 9f 02 00 48 83 c4 18 c3 0f 1f 80 00 00 00 00 48 89 f8 48
89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d
01 f0 ff ff 0f 83 9b 6b fc ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f1ea15edc68 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007f1ea15ee6cc RCX: 00000000004497b9
RDX: 0000000000001000 RSI: 0000000020000140 RDI: 0000000000000013
RBP: 000000000071bea0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
R13: 000000000000bb50 R14: 00000000006f4bf0 R15: 00007f1ea15ee700
=========================================
As I checked, this uninitialized variable won't cause extent cache
corruption, but in order to avoid such kind of warning of both UBSAN
and smatch, fix to initialize related variable.
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Reported-by: Eric Biggers <ebiggers@google.com>
Reported-by: Kyungtae Kim <kt0755@gmail.com>
Signed-off-by: Chao Yu <yuchao0@huawei.com>
---
fs/f2fs/extent_cache.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/fs/f2fs/extent_cache.c b/fs/f2fs/extent_cache.c
index 1cb0fcc67d2d..caf77fe8ac07 100644
--- a/fs/f2fs/extent_cache.c
+++ b/fs/f2fs/extent_cache.c
@@ -506,7 +506,7 @@ static void f2fs_update_extent_tree_range(struct inode *inode,
unsigned int end = fofs + len;
unsigned int pos = (unsigned int)fofs;
bool updated = false;
- bool leftmost;
+ bool leftmost = false;
if (!et)
return;
--
2.18.0.rc1
reply other threads:[~2019-01-16 1:52 UTC|newest]
Thread overview: [no followups] expand[flat|nested] mbox.gz Atom feed
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20190116015128.112292-1-yuchao0@huawei.com \
--to=yuchao0@huawei.com \
--cc=chao@kernel.org \
--cc=dan.carpenter@oracle.com \
--cc=ebiggers@google.com \
--cc=jaegeuk@kernel.org \
--cc=kt0755@gmail.com \
--cc=linux-f2fs-devel@lists.sourceforge.net \
--cc=linux-kernel@vger.kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).