UbiquitousOS
/
OpenCloudOS-Kernel
mirror of https://gitee.com/OpenCloudOS/OpenCloudOS-Kernel.git
11
0
Fork 0
Code Issues Projects Releases Wiki Activity

gfs2: fix an oops in gfs2_permission 

[ Upstream commit 0abd1557e21c617bd13fc18f7725fc6363c05913 ]

In RCU mode, we might race with gfs2_evict_inode(), which zeroes
->i_gl.  Freeing of the object it points to is RCU-delayed, so
if we manage to fetch the pointer before it's been replaced with
NULL, we are fine.  Check if we'd fetched NULL and treat that
as "bail out and tell the caller to get out of RCU mode".

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Al Viro 2023-10-02 03:33:44 +01:00 committed by Greg Kroah-Hartman
parent 119565e566
commit 7f9b5e974c
2 changed files with 10 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

11
fs/gfs2/inode.c
View File

@ -1868,14 +1868,21 @@ int gfs2_permission(struct mnt_idmap *idmap, struct inode *inode,
{
struct gfs2_inode *ip;
struct gfs2_holder i_gh;
struct gfs2_glock *gl;
int error;
gfs2_holder_mark_uninitialized(&i_gh);
ip = GFS2_I(inode);
if (gfs2_glock_is_locked_by_me(ip->i_gl) == NULL) {
gl = rcu_dereference(ip->i_gl);
if (unlikely(!gl)) {
/* inode is getting torn down, must be RCU mode */
WARN_ON_ONCE(!(mask & MAY_NOT_BLOCK));
return -ECHILD;
}
if (gfs2_glock_is_locked_by_me(gl) == NULL) {
if (mask & MAY_NOT_BLOCK)
return -ECHILD;
error = gfs2_glock_nq_init(ip->i_gl, LM_ST_SHARED, LM_FLAG_ANY, &i_gh);
error = gfs2_glock_nq_init(gl, LM_ST_SHARED, LM_FLAG_ANY, &i_gh);
if (error)
return error;
}

2
fs/gfs2/super.c
View File

@ -1550,7 +1550,7 @@ out:
wait_on_bit_io(&ip->i_flags, GIF_GLOP_PENDING, TASK_UNINTERRUPTIBLE);
gfs2_glock_add_to_lru(ip->i_gl);
gfs2_glock_put_eventually(ip->i_gl);
ip->i_gl = NULL;
rcu_assign_pointer(ip->i_gl, NULL);
}
}