From: Roberto Sassu <roberto.sassu@huaweicloud.com>
To: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>,
syzbot <syzbot+7bc44a489f0ef0670bd5@syzkaller.appspotmail.com>,
syzkaller-bugs@googlegroups.com, Gao Xiang <xiang@kernel.org>,
Chao Yu <chao@kernel.org>, Yue Hu <huyue2@coolpad.com>,
Jeffle Xu <jefflexu@linux.alibaba.com>
Cc: linux-kernel@vger.kernel.org, linux-erofs@lists.ozlabs.org,
linux-integrity@vger.kernel.org, zohar@linux.ibm.com
Subject: Re: [syzbot] [integrity?] [lsm?] KMSAN: uninit-value in ima_add_template_entry
Date: Mon, 04 Mar 2024 09:15:21 +0100 [thread overview]
Message-ID: <51ee454cf93c24afbfc9f159a1b8428d9d6e3be7.camel@huaweicloud.com> (raw)
In-Reply-To: <ab2a337d-c2dd-437d-9ab8-e3b837f1ff1a@I-love.SAKURA.ne.jp>
On Sun, 2024-03-03 at 23:54 +0900, Tetsuo Handa wrote:
> On 2024/02/20 19:40, Roberto Sassu wrote:
> > On Mon, 2024-02-19 at 22:41 -0800, syzbot wrote:
> > > Hello,
> > >
> > > syzbot found the following issue on:
> > >
> > > HEAD commit: 4f5e5092fdbf Merge tag 'net-6.8-rc5' of git://git.kernel.o..
> > > git tree: upstream
> > > console output: https://syzkaller.appspot.com/x/log.txt?x=135ba81c180000
> > > kernel config: https://syzkaller.appspot.com/x/.config?x=e3dd779fba027968
> > > dashboard link: https://syzkaller.appspot.com/bug?extid=7bc44a489f0ef0670bd5
> > > compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
>
> > I would add the VFS people in CC, in case they have some ideas.
>
> This is an erofs bug. Since the filesystem image in the reproducer
> is crafted, decompression generates bogus result and
> z_erofs_transform_plain() misbehaves.
Thank you Tetsuo, and Gao Xiang for fixing it!
Roberto
> You can obtain a single-threaded reproducer from
> https://syzkaller.appspot.com/x/repro.c?x=1256096a180000 with below diff.
>
> ----------------------------------------
> --- old/1256096a180000.c
> +++ new/1256096a180000.c
> @@ -676,6 +676,6 @@
> syscall(__NR_mmap, /*addr=*/0x21000000ul, /*len=*/0x1000ul, /*prot=*/0ul,
> /*flags=MAP_FIXED|MAP_ANONYMOUS|MAP_PRIVATE*/ 0x32ul, /*fd=*/-1,
> /*offset=*/0ul);
> - loop();
> + execute_one();
> return 0;
> }
> ----------------------------------------
>
> With CONFIG_EROFS_FS_DEBUG=y, the reproducer hits DBG_BUGON().
> With debug printk() shown below, you can get output shown below.
>
> ----------------------------------------
> diff --git a/fs/erofs/decompressor.c b/fs/erofs/decompressor.c
> index d4cee95af14c..f221133a0731 100644
> --- a/fs/erofs/decompressor.c
> +++ b/fs/erofs/decompressor.c
> @@ -323,7 +323,11 @@ static int z_erofs_transform_plain(struct z_erofs_decompress_req *rq,
> unsigned int cur = 0, ni = 0, no, pi, po, insz, cnt;
> u8 *kin;
>
> - DBG_BUGON(rq->outputsize > rq->inputsize);
> + if (rq->outputsize > rq->inputsize) {
> + pr_err("rq->inputsize=%u rq->outputsize=%u\n", rq->inputsize, rq->outputsize);
> + pr_err("rq->pageofs_in=%u rq->pageofs_out=%u\n", rq->pageofs_in, rq->pageofs_out);
> + pr_err("nrpages_in=%u nrpages_out=%u\n", nrpages_in, nrpages_out);
> + }
> if (rq->alg == Z_EROFS_COMPRESSION_INTERLACED) {
> cur = bs - (rq->pageofs_out & (bs - 1));
> pi = (rq->pageofs_in + rq->inputsize - cur) & ~PAGE_MASK;
> @@ -352,7 +356,8 @@ static int z_erofs_transform_plain(struct z_erofs_decompress_req *rq,
> do {
> no = (rq->pageofs_out + cur + pi) >> PAGE_SHIFT;
> po = (rq->pageofs_out + cur + pi) & ~PAGE_MASK;
> - DBG_BUGON(no >= nrpages_out);
> + if (no >= nrpages_out)
> + pr_err("no=%u nrpages_out=%u\n", no, nrpages_out);
> cnt = min(insz - pi, PAGE_SIZE - po);
> if (rq->out[no] == rq->in[ni]) {
> memmove(kin + po,
> @@ -366,7 +371,8 @@ static int z_erofs_transform_plain(struct z_erofs_decompress_req *rq,
> } while (pi < insz);
> kunmap_local(kin);
> }
> - DBG_BUGON(ni > nrpages_in);
> + if (ni > nrpages_in)
> + pr_err("ni=%u nrpages_in=%u\n", ni, nrpages_in);
> return 0;
> }
>
> ----------------------------------------
>
> ----------------------------------------
> [ 138.991810][ T2983] loop0: detected capacity change from 0 to 16
> [ 139.804002][ T2983] erofs: (device loop0): mounted with root inode @ nid 36.
> [ 139.810464][ T87] erofs: rq->inputsize=4096 rq->outputsize=8194
> [ 139.821540][ T87] erofs: rq->pageofs_in=0 rq->pageofs_out=0
> [ 139.824347][ T87] erofs: nrpages_in=1 nrpages_out=3
> [ 139.827008][ T87] erofs: ni=3 nrpages_in=1
> [ 139.873777][ T2983] =====================================================
> [ 139.881268][ T2983] BUG: KMSAN: uninit-value in ima_add_template_entry+0x626/0xa80
> ----------------------------------------
>
> #syz set subsystems: erofs
next prev parent reply other threads:[~2024-03-04 8:15 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-02-20 6:41 [syzbot] [integrity?] [lsm?] KMSAN: uninit-value in ima_add_template_entry syzbot
2024-02-20 10:40 ` Roberto Sassu
[not found] ` <ab2a337d-c2dd-437d-9ab8-e3b837f1ff1a@I-love.SAKURA.ne.jp>
2024-03-04 8:15 ` Roberto Sassu [this message]
2024-03-02 22:01 ` [syzbot] [lsm?] [integrity?] " syzbot
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=51ee454cf93c24afbfc9f159a1b8428d9d6e3be7.camel@huaweicloud.com \
--to=roberto.sassu@huaweicloud.com \
--cc=chao@kernel.org \
--cc=huyue2@coolpad.com \
--cc=jefflexu@linux.alibaba.com \
--cc=linux-erofs@lists.ozlabs.org \
--cc=linux-integrity@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=penguin-kernel@I-love.SAKURA.ne.jp \
--cc=syzbot+7bc44a489f0ef0670bd5@syzkaller.appspotmail.com \
--cc=syzkaller-bugs@googlegroups.com \
--cc=xiang@kernel.org \
--cc=zohar@linux.ibm.com \
/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 read-only IMAP folder(s) and NNTP newsgroup(s).