Commit 63469662 authored by Luis Henriques (SUSE)'s avatar Luis Henriques (SUSE) Committed by Theodore Ts'o
Browse files

ext4: fix possible tid_t sequence overflows 



In the fast commit code there are a few places where tid_t variables are
being compared without taking into account the fact that these sequence
numbers may wrap.  Fix this issue by using the helper functions tid_gt()
and tid_geq().

Signed-off-by: default avatarLuis Henriques (SUSE) <luis.henriques@linux.dev>
Reviewed-by: default avatarJan Kara <jack@suse.cz>
Reviewed-by: default avatarHarshad Shirwadkar <harshadshirwadkar@gmail.com>
Link: https://patch.msgid.link/20240529092030.9557-3-luis.henriques@linux.dev


Signed-off-by: default avatarTheodore Ts'o <tytso@mit.edu>
parent 2d4d6bda

fs/ext4/fast_commit.c

+4 −4
Original line number Diff line number Diff line
@@ -353,7 +353,7 @@ void ext4_fc_mark_ineligible(struct super_block *sb, int reason, handle_t *handl 
		read_unlock(&sbi->s_journal->j_state_lock);

	}

	spin_lock(&sbi->s_fc_lock);

	if (sbi->s_fc_ineligible_tid < tid)

	if (tid_gt(tid, sbi->s_fc_ineligible_tid))

		sbi->s_fc_ineligible_tid = tid;

	spin_unlock(&sbi->s_fc_lock);

	WARN_ON(reason >= EXT4_FC_REASON_MAX);
@@ -1207,7 +1207,7 @@ int ext4_fc_commit(journal_t *journal, tid_t commit_tid) 
	if (ret == -EALREADY) {

		/* There was an ongoing commit, check if we need to restart */

		if (atomic_read(&sbi->s_fc_subtid) <= subtid &&

			commit_tid > journal->j_commit_sequence)

		    tid_gt(commit_tid, journal->j_commit_sequence))

			goto restart_fc;

		ext4_fc_update_stats(sb, EXT4_FC_STATUS_SKIPPED, 0, 0,

				commit_tid);
@@ -1282,7 +1282,7 @@ static void ext4_fc_cleanup(journal_t *journal, int full, tid_t tid) 
		list_del_init(&iter->i_fc_list);

		ext4_clear_inode_state(&iter->vfs_inode,

				       EXT4_STATE_FC_COMMITTING);

		if (iter->i_sync_tid <= tid)

		if (tid_geq(tid, iter->i_sync_tid))

			ext4_fc_reset_inode(&iter->vfs_inode);

		/* Make sure EXT4_STATE_FC_COMMITTING bit is clear */

		smp_mb();
@@ -1313,7 +1313,7 @@ static void ext4_fc_cleanup(journal_t *journal, int full, tid_t tid) 
	list_splice_init(&sbi->s_fc_q[FC_Q_STAGING],

				&sbi->s_fc_q[FC_Q_MAIN]);



	if (tid >= sbi->s_fc_ineligible_tid) {

	if (tid_geq(tid, sbi->s_fc_ineligible_tid)) {

		sbi->s_fc_ineligible_tid = 0;

		ext4_clear_mount_flag(sb, EXT4_MF_FC_INELIGIBLE);

	}