All of lore.kernel.org
 help / color / mirror / Atom feed
From: "Sungjong Seo" <sj1557.seo@samsung.com>
To: "'Tadeusz Struk'" <tadeusz.struk@linaro.org>, <linkinjeon@kernel.org>
Cc: <linux-fsdevel@vger.kernel.org>, <stable@vger.kernel.org>,
	<linux-kernel@vger.kernel.org>,
	<syzbot+a4087e40b9c13aad7892@syzkaller.appspotmail.com>,
	<sj1557.seo@samsung.com>
Subject: RE: [PATCH v2 2/2] exfat: check if cluster num is valid
Date: Sun, 15 May 2022 23:52:03 +0900	[thread overview]
Message-ID: <000101d8686b$56d88750$048995f0$@samsung.com> (raw)
In-Reply-To: <20220511185909.175110-2-tadeusz.struk@linaro.org>

> Syzbot reported slab-out-of-bounds read in exfat_clear_bitmap.
> This was triggered by reproducer calling truncute with size 0, which
> causes the following trace:
> 
> BUG: KASAN: slab-out-of-bounds in exfat_clear_bitmap+0x147/0x490
> fs/exfat/balloc.c:174 Read of size 8 at addr ffff888115aa9508 by task syz-
> executor251/365
> 
> Call Trace:
>  __dump_stack lib/dump_stack.c:77 [inline]  dump_stack_lvl+0x1e2/0x24b
> lib/dump_stack.c:118
>  print_address_description+0x81/0x3c0 mm/kasan/report.c:233
> __kasan_report mm/kasan/report.c:419 [inline]
>  kasan_report+0x1a4/0x1f0 mm/kasan/report.c:436
>  __asan_report_load8_noabort+0x14/0x20 mm/kasan/report_generic.c:309
>  exfat_clear_bitmap+0x147/0x490 fs/exfat/balloc.c:174
>  exfat_free_cluster+0x25a/0x4a0 fs/exfat/fatent.c:181
>  __exfat_truncate+0x99e/0xe00 fs/exfat/file.c:217
>  exfat_truncate+0x11b/0x4f0 fs/exfat/file.c:243
>  exfat_setattr+0xa03/0xd40 fs/exfat/file.c:339
>  notify_change+0xb76/0xe10 fs/attr.c:336
>  do_truncate+0x1ea/0x2d0 fs/open.c:65
> 
> Add checks to validate if cluster number is within valid range in
> exfat_clear_bitmap() and exfat_set_bitmap()
> 
> Cc: Namjae Jeon <linkinjeon@kernel.org>
> Cc: Sungjong Seo <sj1557.seo@samsung.com>
> Cc: linux-fsdevel@vger.kernel.org
> Cc: stable@vger.kernel.org
> Cc: linux-kernel@vger.kernel.org
> 
> Link: https://protect2.fireeye.com/v1/url?k=24a746d8-45dcec51-24a6cd97-
> 74fe48600034-8e4653a49a463f3c&q=1&e=0efc824d-6463-4253-9cd7-
> ce3199dbf513&u=https%3A%2F%2Fsyzkaller.appspot.com%2Fbug%3Fid%3D50381fc738
> 21ecae743b8cf24b4c9a04776f767c
> Reported-by: syzbot+a4087e40b9c13aad7892@syzkaller.appspotmail.com
> Fixes: 1e49a94cf707 ("exfat: add bitmap operations")
> Signed-off-by: Tadeusz Struk <tadeusz.struk@linaro.org>

Looks good.
And it seems that WARN_ON() is no longer needed.

Reviewed-by: Sungjong Seo <sj1557.seo@samsung.com>

> ---
> v2:
>  - Use is_valid_cluster() helper to validate clu
> ---
>  fs/exfat/balloc.c | 6 ++++++
>  1 file changed, 6 insertions(+)
> 
> diff --git a/fs/exfat/balloc.c b/fs/exfat/balloc.c index
> 03f142307174..92f5b5b5a0d0 100644
> --- a/fs/exfat/balloc.c
> +++ b/fs/exfat/balloc.c
> @@ -149,6 +149,9 @@ int exfat_set_bitmap(struct inode *inode, unsigned int
> clu, bool sync)
>  	struct exfat_sb_info *sbi = EXFAT_SB(sb);
> 
>  	WARN_ON(clu < EXFAT_FIRST_CLUSTER);
> +	if (!is_valid_cluster(sbi, clu))
> +		return -EINVAL;
> +
>  	ent_idx = CLUSTER_TO_BITMAP_ENT(clu);
>  	i = BITMAP_OFFSET_SECTOR_INDEX(sb, ent_idx);
>  	b = BITMAP_OFFSET_BIT_IN_SECTOR(sb, ent_idx); @@ -167,6 +170,9 @@
> void exfat_clear_bitmap(struct inode *inode, unsigned int clu, bool sync)
>  	struct exfat_mount_options *opts = &sbi->options;
> 
>  	WARN_ON(clu < EXFAT_FIRST_CLUSTER);
> +	if (!is_valid_cluster(sbi, clu))
> +		return;
> +
>  	ent_idx = CLUSTER_TO_BITMAP_ENT(clu);
>  	i = BITMAP_OFFSET_SECTOR_INDEX(sb, ent_idx);
>  	b = BITMAP_OFFSET_BIT_IN_SECTOR(sb, ent_idx);
> --
> 2.36.1



  reply	other threads:[~2022-05-15 14:52 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <CGME20220511185940epcas1p3c5eb0603b969fe2753b4f16f6f8842a7@epcas1p3.samsung.com>
2022-05-11 18:59 ` [PATCH v2 1/2] exfat: move is_valid_cluster to a common header Tadeusz Struk
2022-05-11 18:59   ` [PATCH v2 2/2] exfat: check if cluster num is valid Tadeusz Struk
2022-05-15 14:52     ` Sungjong Seo [this message]
2022-05-16 14:51       ` Tadeusz Struk
2022-05-16 23:31         ` Namjae Jeon
2022-05-16 23:38           ` Tadeusz Struk
2022-05-15 14:38   ` [PATCH v2 1/2] exfat: move is_valid_cluster to a common header Sungjong Seo

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='000101d8686b$56d88750$048995f0$@samsung.com' \
    --to=sj1557.seo@samsung.com \
    --cc=linkinjeon@kernel.org \
    --cc=linux-fsdevel@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=stable@vger.kernel.org \
    --cc=syzbot+a4087e40b9c13aad7892@syzkaller.appspotmail.com \
    --cc=tadeusz.struk@linaro.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 an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.