linux-kernel - Re: KASAN: null-ptr-deref Write in get

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Message-ID: <CADG63jAEOBvWZ2G-9tyvHbbuKnHxNTPpqqjfWmhP7YVvsHVioQ@mail.gmail.com>
Date:   Sun, 22 Mar 2020 20:06:48 +0800
From:   Qiujun Huang <anenbupt@...il.com>
To:     syzbot <syzbot+4a88b2b9dc280f47baf4@...kaller.appspotmail.com>
Cc:     aeb@....nl, danarag@...il.com, kstewart@...uxfoundation.org,
        linux-kernel@...r.kernel.org, syzkaller-bugs@...glegroups.com,
        tglx@...utronix.de, viro@...iv.linux.org.uk
Subject: Re: KASAN: null-ptr-deref Write in get_block

Need to check the return value of sb_getblk.

Signed-off-by: Qiujun Huang <hqjagain@...il.com>
---
 fs/minix/itree_common.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/fs/minix/itree_common.c b/fs/minix/itree_common.c
index 043c3fd..eedd79f 100644
--- a/fs/minix/itree_common.c
+++ b/fs/minix/itree_common.c
@@ -85,6 +85,8 @@ static int alloc_branch(struct inode *inode,
  break;
  branch[n].key = cpu_to_block(nr);
  bh = sb_getblk(inode->i_sb, parent);
+ if (!bh)
+ break;
  lock_buffer(bh);
  memset(bh->b_data, 0, bh->b_size);
  branch[n].bh = bh;
--