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gfs2: Fix possible data races in gfs2_show_options()

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[ Upstream commit 6fa0a72cbb ]

Some fields such as gt_logd_secs of the struct gfs2_tune are accessed
without holding the lock gt_spin in gfs2_show_options():

  val = sdp->sd_tune.gt_logd_secs;
  if (val != 30)
    seq_printf(s, ",commit=%d", val);

And thus can cause data races when gfs2_show_options() and other functions
such as gfs2_reconfigure() are concurrently executed:

  spin_lock(&gt->gt_spin);
  gt->gt_logd_secs = newargs->ar_commit;

To fix these possible data races, the lock sdp->sd_tune.gt_spin is
acquired before accessing the fields of gfs2_tune and released after these
accesses.

Further changes by Andreas:

- Don't hold the spin lock over the seq_printf operations.

Reported-by: BassCheck <bass@buaa.edu.cn>
Signed-off-by: Tuo Li <islituo@gmail.com>
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Tuo Li 2023-06-13 11:06:37 +08:00 • committed by Justin Hammond
parent c81af1abc1
commit 75bf22764d
1 changed files with 15 additions and 11 deletions
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26
fs/gfs2/super.c
View file

@ -980,7 +980,14 @@ static int gfs2_show_options(struct seq_file *s, struct dentry *root)
{
struct gfs2_sbd *sdp = root->d_sb->s_fs_info;
struct gfs2_args *args = &sdp->sd_args;
int val;
unsigned int logd_secs, statfs_slow, statfs_quantum, quota_quantum;
spin_lock(&sdp->sd_tune.gt_spin);
logd_secs = sdp->sd_tune.gt_logd_secs;
quota_quantum = sdp->sd_tune.gt_quota_quantum;
statfs_quantum = sdp->sd_tune.gt_statfs_quantum;
statfs_slow = sdp->sd_tune.gt_statfs_slow;
spin_unlock(&sdp->sd_tune.gt_spin);
if (is_ancestor(root, sdp->sd_master_dir))
seq_puts(s, ",meta");
@ -1035,17 +1042,14 @@ static int gfs2_show_options(struct seq_file *s, struct dentry *root)
}
if (args->ar_discard)
seq_puts(s, ",discard");
val = sdp->sd_tune.gt_logd_secs;
if (val != 30)
seq_printf(s, ",commit=%d", val);
val = sdp->sd_tune.gt_statfs_quantum;
if (val != 30)
seq_printf(s, ",statfs_quantum=%d", val);
else if (sdp->sd_tune.gt_statfs_slow)
if (logd_secs != 30)
seq_printf(s, ",commit=%d", logd_secs);
if (statfs_quantum != 30)
seq_printf(s, ",statfs_quantum=%d", statfs_quantum);
else if (statfs_slow)
seq_puts(s, ",statfs_quantum=0");
val = sdp->sd_tune.gt_quota_quantum;
if (val != 60)
seq_printf(s, ",quota_quantum=%d", val);
if (quota_quantum != 60)
seq_printf(s, ",quota_quantum=%d", quota_quantum);
if (args->ar_statfs_percent)
seq_printf(s, ",statfs_percent=%d", args->ar_statfs_percent);
if (args->ar_errors != GFS2_ERRORS_DEFAULT) {