From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 16036101C0 for ; Mon, 15 May 2023 17:51:35 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 878BCC433D2; Mon, 15 May 2023 17:51:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1684173094; bh=dbioeZD80QGJiAVPO1qyKT8fDeCAUEE1jA1jbClvWAw=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=fvQqV1rgVCyEtssy6SWK5RQpCCqWS8Z1CgMTJNbBKrkm6aBFbL1sIA9pNPc7p5/iD E8g7r7HMc4Jaly4t4gpTB/rM047lZZ9dVKiz1UPBtM0GS2cO9eGTmtB/PqFXNH9WZ7 29kvvrb6yCOmyYjzD1jDQLVkgD/M5ZKgBLV/kQbI= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, stable@kernel.org, syzbot+e2efa3efc15a1c9e95c3@syzkaller.appspotmail.com, Theodore Tso Subject: [PATCH 5.10 366/381] ext4: remove a BUG_ON in ext4_mb_release_group_pa() Date: Mon, 15 May 2023 18:30:17 +0200 Message-Id: <20230515161753.444227206@linuxfoundation.org> X-Mailer: git-send-email 2.40.1 In-Reply-To: <20230515161736.775969473@linuxfoundation.org> References: <20230515161736.775969473@linuxfoundation.org> User-Agent: quilt/0.67 Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit From: Theodore Ts'o commit 463808f237cf73e98a1a45ff7460c2406a150a0b upstream. If a malicious fuzzer overwrites the ext4 superblock while it is mounted such that the s_first_data_block is set to a very large number, the calculation of the block group can underflow, and trigger a BUG_ON check. Change this to be an ext4_warning so that we don't crash the kernel. Cc: stable@kernel.org Link: https://lore.kernel.org/r/20230430154311.579720-3-tytso@mit.edu Reported-by: syzbot+e2efa3efc15a1c9e95c3@syzkaller.appspotmail.com Link: https://syzkaller.appspot.com/bug?id=69b28112e098b070f639efb356393af3ffec4220 Signed-off-by: Theodore Ts'o Signed-off-by: Greg Kroah-Hartman --- fs/ext4/mballoc.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) --- a/fs/ext4/mballoc.c +++ b/fs/ext4/mballoc.c @@ -4250,7 +4250,11 @@ ext4_mb_release_group_pa(struct ext4_bud trace_ext4_mb_release_group_pa(sb, pa); BUG_ON(pa->pa_deleted == 0); ext4_get_group_no_and_offset(sb, pa->pa_pstart, &group, &bit); - BUG_ON(group != e4b->bd_group && pa->pa_len != 0); + if (unlikely(group != e4b->bd_group && pa->pa_len != 0)) { + ext4_warning(sb, "bad group: expected %u, group %u, pa_start %llu", + e4b->bd_group, group, pa->pa_pstart); + return 0; + } mb_free_blocks(pa->pa_inode, e4b, bit, pa->pa_len); atomic_add(pa->pa_len, &EXT4_SB(sb)->s_mb_discarded); trace_ext4_mballoc_discard(sb, NULL, group, bit, pa->pa_len);