]> www.infradead.org Git - users/willy/xarray.git/commit
ext4: fix i_data_sem unlock order in ext4_ind_migrate()
authorArtem Sadovnikov <ancowi69@gmail.com>
Thu, 29 Aug 2024 15:22:09 +0000 (15:22 +0000)
committerTheodore Ts'o <tytso@mit.edu>
Wed, 4 Sep 2024 02:14:17 +0000 (22:14 -0400)
commitcc749e61c011c255d81b192a822db650c68b313f
tree6fe2486119aae77a74f0e414cbd81110fcf1d7da
parent183aa1d3baea18b199505455a0247b13de826e2f
ext4: fix i_data_sem unlock order in ext4_ind_migrate()

Fuzzing reports a possible deadlock in jbd2_log_wait_commit.

This issue is triggered when an EXT4_IOC_MIGRATE ioctl is set to require
synchronous updates because the file descriptor is opened with O_SYNC.
This can lead to the jbd2_journal_stop() function calling
jbd2_might_wait_for_commit(), potentially causing a deadlock if the
EXT4_IOC_MIGRATE call races with a write(2) system call.

This problem only arises when CONFIG_PROVE_LOCKING is enabled. In this
case, the jbd2_might_wait_for_commit macro locks jbd2_handle in the
jbd2_journal_stop function while i_data_sem is locked. This triggers
lockdep because the jbd2_journal_start function might also lock the same
jbd2_handle simultaneously.

Found by Linux Verification Center (linuxtesting.org) with syzkaller.

Reviewed-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com>
Co-developed-by: Mikhail Ukhin <mish.uxin2012@yandex.ru>
Signed-off-by: Mikhail Ukhin <mish.uxin2012@yandex.ru>
Signed-off-by: Artem Sadovnikov <ancowi69@gmail.com>
Rule: add
Link: https://lore.kernel.org/stable/20240404095000.5872-1-mish.uxin2012%40yandex.ru
Link: https://patch.msgid.link/20240829152210.2754-1-ancowi69@gmail.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
fs/ext4/migrate.c