ext4: fix del_timer() misuse for ->s_err_report (9105bb14) · Commits · 戴 / test

That thing should be del_timer_sync(); consider what happens if ext4_put_super() call of del_timer() happens to come just as it's getting run on another CPU. Since that timer reschedules itself to run next day, you are pretty much guaranteed that you'll end up with kfree'd scheduled timer, with usual fun consequences. AFAICS, that's -stable fodder all way back to 2010... [the second del_timer_sync() is almost certainly not needed, but it doesn't hurt either] Signed-off-by:

Al Viro <viro@zeniv.linux.org.uk> Signed-off-by:

"Theodore Ts'o" <tytso@mit.edu> Cc: stable@vger.kernel.org

fs/ext4/super.c

+2 −2

Original line number	Original line	Diff line number	Diff line
	@@ -792,7 +792,7 @@ static void ext4_put_super(struct super_block *sb)
	}		}

	ext4_es_unregister_shrinker(sbi);		ext4_es_unregister_shrinker(sbi);
	del_timer(&sbi->s_err_report);		del_timer_sync(&sbi->s_err_report);
	ext4_release_system_zone(sb);		ext4_release_system_zone(sb);
	ext4_mb_release(sb);		ext4_mb_release(sb);
	ext4_ext_release(sb);		ext4_ext_release(sb);
	@@ -4184,7 +4184,7 @@ failed_mount_wq:
	}		}
	failed_mount3:		failed_mount3:
	ext4_es_unregister_shrinker(sbi);		ext4_es_unregister_shrinker(sbi);
	del_timer(&sbi->s_err_report);		del_timer_sync(&sbi->s_err_report);
	if (sbi->s_flex_groups)		if (sbi->s_flex_groups)
	ext4_kvfree(sbi->s_flex_groups);		ext4_kvfree(sbi->s_flex_groups);
	percpu_counter_destroy(&sbi->s_freeclusters_counter);		percpu_counter_destroy(&sbi->s_freeclusters_counter);

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