From: Prince Kumar Maurya <princekumarmaurya06@xxxxxxxxx> 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@xxxxxxxxxxxxxxxxxxxxxxxxx Closes: https://syzkaller.appspot.com/bug?extid=aad58150cbc64ba41bdc Signed-off-by: Prince Kumar Maurya <princekumarmaurya06@xxxxxxxxx> Message-Id: <20230531013141.19487-1-princekumarmaurya06@xxxxxxxxx> Signed-off-by: Christian Brauner <brauner@xxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- fs/sysv/itree.c | 4 ++++ 1 file changed, 4 insertions(+) --- a/fs/sysv/itree.c +++ b/fs/sysv/itree.c @@ -145,6 +145,10 @@ static int alloc_branch(struct inode *in */ 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;
