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gfs2: Don't clear sb->s_fs_info in gfs2_sys_fs_add

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commit 9126d2754c upstream.

When gfs2_sys_fs_add() fails, it sets sb->s_fs_info to NULL on its error
path (see commit 0d515210b6 ("GFS2: Add kobject release method")).
The intention seems to be to prevent dereferencing sb->s_fs_info once
the object pointed to has been deallocated, but that would be better
achieved by setting the pointer to NULL in free_sbd().

As a consequence, when the call to gfs2_sys_fs_add() fails in
gfs2_fill_super(), sdp = GFS2_SB(inode) will evaluate to NULL in iput()
-> gfs2_drop_inode(), and accessing sdp->sd_flags will be a NULL pointer
dereference.

Fix that by only setting sb->s_fs_info to NULL when actually freeing the
object pointed to in free_sbd().

Fixes: ae9f3bd825 ("gfs2: replace sd_aspace with sd_inode")
Reported-by: syzbot+b12826218502df019f9d@syzkaller.appspotmail.com
Signed-off-by: Andrew Price <anprice@redhat.com>
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Andrew Price 2025-05-28 16:02:37 +01:00 committed by Greg Kroah-Hartman
parent ab20b0bdb0
commit da728507b0
2 changed files with 3 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
fs/gfs2/ops_fstype.c
View File

@ -64,8 +64,11 @@ static void gfs2_tune_init(struct gfs2_tune *gt)
void free_sbd(struct gfs2_sbd *sdp) void free_sbd(struct gfs2_sbd *sdp)
{ {
struct super_block *sb = sdp->sd_vfs;
if (sdp->sd_lkstats) if (sdp->sd_lkstats)
free_percpu(sdp->sd_lkstats); free_percpu(sdp->sd_lkstats);
sb->s_fs_info = NULL;
kfree(sdp); kfree(sdp);
} }
@ -1316,7 +1319,6 @@ fail_iput:
iput(sdp->sd_inode); iput(sdp->sd_inode);
fail_free: fail_free:
free_sbd(sdp); free_sbd(sdp);
sb->s_fs_info = NULL;
return error; return error;
} }

1
fs/gfs2/sys.c
View File

@ -764,7 +764,6 @@ fail_reg:
fs_err(sdp, "error %d adding sysfs files\n", error); fs_err(sdp, "error %d adding sysfs files\n", error);
kobject_put(&sdp->sd_kobj); kobject_put(&sdp->sd_kobj);
wait_for_completion(&sdp->sd_kobj_unregister); wait_for_completion(&sdp->sd_kobj_unregister);
sb->s_fs_info = NULL;
return error; return error;
} }