From: Richard Weinberger <richard@nod.at> To: Chengsong Ke <kechengsong@huawei.com> Cc: Sascha Hauer <s.hauer@pengutronix.de>, linux-mtd <linux-mtd@lists.infradead.org>, linux-kernel <linux-kernel@vger.kernel.org>, wangfangpeng1 <wangfangpeng1@huawei.com>, chengzhihao1 <chengzhihao1@huawei.com> Subject: Re: [PATCH v2] ubifs: Fix read out-of-bounds in ubifs_jnl_write_inode() Date: Thu, 24 Dec 2020 00:07:20 +0100 (CET) [thread overview] Message-ID: <244303467.160590.1608764840819.JavaMail.zimbra@nod.at> (raw) In-Reply-To: <20201223121536.6244-1-kechengsong@huawei.com> Chengsong Ke, ----- Ursprüngliche Mail ----- > The memory area allocated in ubifs_jnl_write_inode() is not aligned with 8 > bytes: > ino_start = ino = kmalloc(write_len, GFP_NOFS); > > When ino_start passed into write_head -> ubifs_wbuf_write_nolock: > n = aligned_len >> c->max_write_shift; > if (n) { > n <<= c->max_write_shift; > err = ubifs_leb_write(c, wbuf->lnum, buf + written, wbuf->offs, n); > // Read oob occurs here, read n bytes from buf, and buf is passed from > @ino_start which is > // not 8 bytes aligned(write_len < n). Program read (n - write_len) more bytes. > } > > Reproducer: > 0. config KASAN && apply print.patch > 1. mount ubifs on /root/temp > 2. run test.sh What does test.sh do? > 3. cd /root/temp && ls // change atime for link_file > 4. wait 1~2 minutes > > In order to solve the read oob problem in ubifs_wbuf_write_nolock, just align > the write_len to > 8 bytes when alloc the memory. So that this patch will not affect the use of > write_len in other > functions, such as ubifs_jnl_write_inode->make_reservation and > ubifs_jnl_write_inode->ubifs_node_calc_hash. I gave this a second thought and I'm not so sure anymore what exactly is going on. The problem is real, I fully agree with you but I need to dig deeper into the journal and wbuf code to double check that we really fix the right thing and not just paper other something. Thanks, //richard
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From: Richard Weinberger <richard@nod.at> To: Chengsong Ke <kechengsong@huawei.com> Cc: chengzhihao1 <chengzhihao1@huawei.com>, Sascha Hauer <s.hauer@pengutronix.de>, linux-mtd <linux-mtd@lists.infradead.org>, linux-kernel <linux-kernel@vger.kernel.org>, wangfangpeng1 <wangfangpeng1@huawei.com> Subject: Re: [PATCH v2] ubifs: Fix read out-of-bounds in ubifs_jnl_write_inode() Date: Thu, 24 Dec 2020 00:07:20 +0100 (CET) [thread overview] Message-ID: <244303467.160590.1608764840819.JavaMail.zimbra@nod.at> (raw) In-Reply-To: <20201223121536.6244-1-kechengsong@huawei.com> Chengsong Ke, ----- Ursprüngliche Mail ----- > The memory area allocated in ubifs_jnl_write_inode() is not aligned with 8 > bytes: > ino_start = ino = kmalloc(write_len, GFP_NOFS); > > When ino_start passed into write_head -> ubifs_wbuf_write_nolock: > n = aligned_len >> c->max_write_shift; > if (n) { > n <<= c->max_write_shift; > err = ubifs_leb_write(c, wbuf->lnum, buf + written, wbuf->offs, n); > // Read oob occurs here, read n bytes from buf, and buf is passed from > @ino_start which is > // not 8 bytes aligned(write_len < n). Program read (n - write_len) more bytes. > } > > Reproducer: > 0. config KASAN && apply print.patch > 1. mount ubifs on /root/temp > 2. run test.sh What does test.sh do? > 3. cd /root/temp && ls // change atime for link_file > 4. wait 1~2 minutes > > In order to solve the read oob problem in ubifs_wbuf_write_nolock, just align > the write_len to > 8 bytes when alloc the memory. So that this patch will not affect the use of > write_len in other > functions, such as ubifs_jnl_write_inode->make_reservation and > ubifs_jnl_write_inode->ubifs_node_calc_hash. I gave this a second thought and I'm not so sure anymore what exactly is going on. The problem is real, I fully agree with you but I need to dig deeper into the journal and wbuf code to double check that we really fix the right thing and not just paper other something. Thanks, //richard ______________________________________________________ Linux MTD discussion mailing list http://lists.infradead.org/mailman/listinfo/linux-mtd/
next prev parent reply other threads:[~2020-12-23 23:08 UTC|newest] Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top 2020-12-23 12:15 [PATCH v2] ubifs: Fix read out-of-bounds in ubifs_jnl_write_inode() Chengsong Ke 2020-12-23 12:15 ` Chengsong Ke 2020-12-23 23:07 ` Richard Weinberger [this message] 2020-12-23 23:07 ` Richard Weinberger 2020-12-24 1:14 ` Zhihao Cheng 2020-12-24 1:14 ` Zhihao Cheng 2021-03-04 1:31 ` [v2] " Chengsong Ke 2021-03-04 1:50 ` Chengsong Ke 2021-03-04 1:50 ` Chengsong Ke
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