6.6-stable review patch. If anyone has any objections, please let me know.
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From: Artem Sadovnikov ancowi69@gmail.com
[ Upstream commit cc749e61c011c255d81b192a822db650c68b313f ]
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.... Link: https://patch.msgid.link/20240829152210.2754-1-ancowi69@gmail.com Signed-off-by: Theodore Ts'o tytso@mit.edu Signed-off-by: Sasha Levin sashal@kernel.org --- fs/ext4/migrate.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/fs/ext4/migrate.c b/fs/ext4/migrate.c index d98ac2af8199f..a5e1492bbaaa5 100644 --- a/fs/ext4/migrate.c +++ b/fs/ext4/migrate.c @@ -663,8 +663,8 @@ int ext4_ind_migrate(struct inode *inode) if (unlikely(ret2 && !ret)) ret = ret2; errout: - ext4_journal_stop(handle); up_write(&EXT4_I(inode)->i_data_sem); + ext4_journal_stop(handle); out_unlock: ext4_writepages_up_write(inode->i_sb, alloc_ctx); return ret;