From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from fanzine2.igalia.com (fanzine.igalia.com [178.60.130.6]) (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 6EFED204F79; Thu, 12 Dec 2024 06:53:48 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=178.60.130.6 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1733986438; cv=none; b=upUGVjBg1Rdq+vJI50Wo1leNgMx/GqzPCf+8dmwFw6pGT6cPPd4T6BzSrOBtgOXvojqxWOe5sjWWjc6YgHIWE9vhjhbH+/+m3vvqbSaGSYohw8kVtUKu9z/MGBexHQC93EW7bLfAIXhmL17zu36WGaXNKuiKc5nw6ttJI0nbCpg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1733986438; c=relaxed/simple; bh=TgwlJ77/RgvziKkQYGCOzJ2NsDawQEyHVPARch2KBkE=; h=From:To:Cc:Subject:Date:Message-Id:MIME-Version; b=Z4E4PiCMPKQemtOLnHTC1D7C6Sj3Ihr0k8I7qDiqbQOyuY1NP1eD2JqFDCQEupZWt2shGlrYWv60JemGqvaXZZnebDC+sijF98wdsJRltuOgqDvdZtu7LiFhJ+Kwe8nlTLuSbxuRoUCajdLUvwK14z5hLlYg8fj/nqW8aaGO56E= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=igalia.com; spf=pass smtp.mailfrom=igalia.com; dkim=pass (2048-bit key) header.d=igalia.com header.i=@igalia.com header.b=S65DYspz; arc=none smtp.client-ip=178.60.130.6 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=igalia.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=igalia.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=igalia.com header.i=@igalia.com header.b="S65DYspz" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=igalia.com; s=20170329; h=Content-Transfer-Encoding:MIME-Version:Message-Id:Date:Subject: Cc:To:From:Sender:Reply-To:Content-Type:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: In-Reply-To:References:List-Id:List-Help:List-Unsubscribe:List-Subscribe: List-Post:List-Owner:List-Archive; bh=5uwvWVdVBwvRd8AQEyf2pjt0urpVyCGtmkA54KS4q2I=; b=S65DYspzDl0dqFsewebT1bxZ+/ woVQtorG+E/1SH8UPXdWRUFD2JY4rtLOb95CQPNJ/1I7cLHrZO1CURr0IPaczK0uwB2KB4Mzz5nOu XM30mn8ZP4eEBM7QGMMzjcfw08t1VhIBg7JlIhp5WxrtDS4TN6zhaUUhO+EAfhMtqh/xeMU9tspVo CT7FK36o6lEIw1uH8xnge+hkp791y/XPOQKgPT1AO30MP6ASQhSRxdnpJGbfCLgn4VO5T9/SLUYCl QVv9WrL9WLjjDXRQPcADF1F7BsCBiFg7v5LGoKdJzE6OSvkYo00X2e6ceYrjasg53OK1vZ1GXh/A8 kxeDQdZg==; Received: from [128.185.11.26] (helo=localhost.localdomain) by fanzine2.igalia.com with esmtpsa (Cipher TLS1.3:ECDHE_X25519__RSA_PSS_RSAE_SHA256__AES_256_GCM:256) (Exim) id 1tLd4x-002AJe-5H; Thu, 12 Dec 2024 07:53:43 +0100 From: Bhupesh To: linux-ext4@vger.kernel.org Cc: bhupesh@igalia.com, tytso@mit.edu, kernel-dev@igalia.com, linux-kernel@vger.kernel.org, revest@google.com, adilger.kernel@dilger.ca, cascardo@igalia.com, syzbot+b244bda78289b00204ed@syzkaller.appspotmail.com Subject: [PATCH 1/1] fs/ext4/xattr: Check for 'xattr_sem' inside 'ext4_xattr_delete_inode' Date: Thu, 12 Dec 2024 12:23:31 +0530 Message-Id: <20241212065331.113465-1-bhupesh@igalia.com> X-Mailer: git-send-email 2.38.1 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Once we are inside the 'ext4_xattr_delete_inode' function and trying to delete the inode, the 'xattr_sem' should be unlocked. We need trylock here to avoid false-positive warning from lockdep about reclaim circular dependency. This fixes the following KASAN reported issue: ================================================================== BUG: KASAN: slab-use-after-free in ext4_xattr_inode_dec_ref_all+0xb8c/0xe90 Read of size 4 at addr ffff888012c120c4 by task repro/2065 CPU: 1 UID: 0 PID: 2065 Comm: repro Not tainted 6.13.0-rc2+ #11 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.16.3-0-ga6ed6b701f0a-prebuilt.qemu.org 04/01/2014 Call Trace: dump_stack_lvl+0x1fd/0x300 ? tcp_gro_dev_warn+0x260/0x260 ? _printk+0xc0/0x100 ? read_lock_is_recursive+0x10/0x10 ? irq_work_queue+0x72/0xf0 ? __virt_addr_valid+0x17b/0x4b0 print_address_description+0x78/0x390 print_report+0x107/0x1f0 ? __virt_addr_valid+0x17b/0x4b0 ? __virt_addr_valid+0x3ff/0x4b0 ? __phys_addr+0xb5/0x160 ? ext4_xattr_inode_dec_ref_all+0xb8c/0xe90 kasan_report+0xcc/0x100 ? ext4_xattr_inode_dec_ref_all+0xb8c/0xe90 ext4_xattr_inode_dec_ref_all+0xb8c/0xe90 ? ext4_xattr_delete_inode+0xd30/0xd30 ? __ext4_journal_ensure_credits+0x5f0/0x5f0 ? __ext4_journal_ensure_credits+0x2b/0x5f0 ? inode_update_timestamps+0x410/0x410 ext4_xattr_delete_inode+0xb64/0xd30 ? ext4_truncate+0xb70/0xdc0 ? ext4_expand_extra_isize_ea+0x1d20/0x1d20 ? __ext4_mark_inode_dirty+0x670/0x670 ? ext4_journal_check_start+0x16f/0x240 ? ext4_inode_is_fast_symlink+0x2f2/0x3a0 ext4_evict_inode+0xc8c/0xff0 ? ext4_inode_is_fast_symlink+0x3a0/0x3a0 ? do_raw_spin_unlock+0x53/0x8a0 ? ext4_inode_is_fast_symlink+0x3a0/0x3a0 evict+0x4ac/0x950 ? proc_nr_inodes+0x310/0x310 ? trace_ext4_drop_inode+0xa2/0x220 ? _raw_spin_unlock+0x1a/0x30 ? iput+0x4cb/0x7e0 do_unlinkat+0x495/0x7c0 ? try_break_deleg+0x120/0x120 ? 0xffffffff81000000 ? __check_object_size+0x15a/0x210 ? strncpy_from_user+0x13e/0x250 ? getname_flags+0x1dc/0x530 __x64_sys_unlinkat+0xc8/0xf0 do_syscall_64+0x65/0x110 entry_SYSCALL_64_after_hwframe+0x67/0x6f RIP: 0033:0x434ffd Code: 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 00 f3 0f 1e fa 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 8 RSP: 002b:00007ffc50fa7b28 EFLAGS: 00000246 ORIG_RAX: 0000000000000107 RAX: ffffffffffffffda RBX: 00007ffc50fa7e18 RCX: 0000000000434ffd RDX: 0000000000000000 RSI: 0000000020000240 RDI: 0000000000000005 RBP: 00007ffc50fa7be0 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001 R13: 00007ffc50fa7e08 R14: 00000000004bbf30 R15: 0000000000000001 The buggy address belongs to the object at ffff888012c12000 which belongs to the cache filp of size 360 The buggy address is located 196 bytes inside of freed 360-byte region [ffff888012c12000, ffff888012c12168) The buggy address belongs to the physical page: page: refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x12c12 head: order:1 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0 flags: 0x40(head|node=0|zone=0) page_type: f5(slab) raw: 0000000000000040 ffff888000ad7640 ffffea0000497a00 dead000000000004 raw: 0000000000000000 0000000000100010 00000001f5000000 0000000000000000 head: 0000000000000040 ffff888000ad7640 ffffea0000497a00 dead000000000004 head: 0000000000000000 0000000000100010 00000001f5000000 0000000000000000 head: 0000000000000001 ffffea00004b0481 ffffffffffffffff 0000000000000000 head: 0000000000000002 0000000000000000 00000000ffffffff 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff888012c11f80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ffff888012c12000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >ffff888012c12080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff888012c12100: fb fb fb fb fb fb fb fb fb fb fb fb fb fc fc fc ffff888012c12180: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ================================================================== Reported-by: syzbot+b244bda78289b00204ed@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=b244bda78289b00204ed Signed-off-by: Bhupesh --- fs/ext4/xattr.c | 16 +++++++++++++++- 1 file changed, 15 insertions(+), 1 deletion(-) diff --git a/fs/ext4/xattr.c b/fs/ext4/xattr.c index 7647e9f6e190..e1d29aa76165 100644 --- a/fs/ext4/xattr.c +++ b/fs/ext4/xattr.c @@ -2926,7 +2926,20 @@ int ext4_xattr_delete_inode(handle_t *handle, struct inode *inode, struct ext4_iloc iloc = { .bh = NULL }; struct ext4_xattr_entry *entry; struct inode *ea_inode; - int error; + int error = 0; + + /* + * We are the only ones holding inode reference. The xattr_sem should + * better be unlocked! We could as well just not acquire xattr_sem at + * all but this makes the code more futureproof. OTOH we need trylock + * here to avoid false-positive warning from lockdep about reclaim + * circular dependency. + */ + if (WARN_ON_ONCE(!down_write_trylock(&EXT4_I(inode)->xattr_sem))) + return error; + + if (!EXT4_I(inode)->i_file_acl) + goto cleanup; error = ext4_journal_ensure_credits(handle, extra_credits, ext4_free_metadata_revoke_credits(inode->i_sb, 1)); @@ -3015,6 +3028,7 @@ int ext4_xattr_delete_inode(handle_t *handle, struct inode *inode, cleanup: brelse(iloc.bh); brelse(bh); + up_write(&EXT4_I(inode)->xattr_sem); return error; } -- 2.38.1