This is a note to let you know that I've just added the patch titled
gfs2: Fix possible data races in gfs2_show_options()
to the 4.14-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
gfs2-fix-possible-data-races-in-gfs2_show_options.patch
and it can be found in the queue-4.14 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 2a97b02506103ae3056041bf4a64f062fddc5003
Author: Tuo Li <islituo@xxxxxxxxx>
Date: Tue Jun 13 11:06:37 2023 +0800
gfs2: Fix possible data races in gfs2_show_options()
[ Upstream commit 6fa0a72cbbe45db4ed967a51f9e6f4e3afe61d20 ]
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_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@xxxxxxxxxxx>
Signed-off-by: Tuo Li <islituo@xxxxxxxxx>
Signed-off-by: Andreas Gruenbacher <agruenba@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/fs/gfs2/super.c b/fs/gfs2/super.c
index 73290263402a3..2167503f17536 100644
--- a/fs/gfs2/super.c
+++ b/fs/gfs2/super.c
@@ -1363,7 +1363,14 @@ 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");
@@ -1418,17 +1425,14 @@ 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) {
