From e28f376dd8dfcc4e880ac101184132bc08703f6e Mon Sep 17 00:00:00 2001 From: Prince Kumar Maurya Date: Tue, 30 May 2023 18:31:41 -0700 Subject: [PATCH] fs/sysv: Null check to prevent null-ptr-deref bug commit ea2b62f305893992156a798f665847e0663c9f41 upstream. sb_getblk(inode->i_sb, parent) return a null ptr and taking lock on that leads to the null-ptr-deref bug. Reported-by: syzbot+aad58150cbc64ba41bdc@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=aad58150cbc64ba41bdc Signed-off-by: Prince Kumar Maurya Message-Id: <20230531013141.19487-1-princekumarmaurya06@gmail.com> Signed-off-by: Christian Brauner Signed-off-by: Greg Kroah-Hartman --- fs/sysv/itree.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/fs/sysv/itree.c b/fs/sysv/itree.c index b22764fe669c84..58d7f43a137125 100644 --- a/fs/sysv/itree.c +++ b/fs/sysv/itree.c @@ -145,6 +145,10 @@ static int alloc_branch(struct inode *inode, */ parent = block_to_cpu(SYSV_SB(inode->i_sb), branch[n-1].key); bh = sb_getblk(inode->i_sb, parent); + if (!bh) { + sysv_free_block(inode->i_sb, branch[n].key); + break; + } lock_buffer(bh); memset(bh->b_data, 0, blocksize); branch[n].bh = bh;