From 504a10d9e46bc37b23d0a1ae2f28973c8516e636 Mon Sep 17 00:00:00 2001 From: Bob Peterson Date: Fri, 28 Apr 2023 12:07:46 -0400 Subject: [PATCH] gfs2: Don't deref jdesc in evict On corrupt gfs2 file systems the evict code can try to reference the journal descriptor structure, jdesc, after it has been freed and set to NULL. The sequence of events is: init_journal() ... fail_jindex: gfs2_jindex_free(sdp); <------frees journals, sets jdesc = NULL if (gfs2_holder_initialized(&ji_gh)) gfs2_glock_dq_uninit(&ji_gh); fail: iput(sdp->sd_jindex); <--references jdesc in evict_linked_inode evict() gfs2_evict_inode() evict_linked_inode() ret = gfs2_trans_begin(sdp, 0, sdp->sd_jdesc->jd_blocks); <------references the now freed/zeroed sd_jdesc pointer. The call to gfs2_trans_begin is done because the truncate_inode_pages call can cause gfs2 events that require a transaction, such as removing journaled data (jdata) blocks from the journal. This patch fixes the problem by adding a check for sdp->sd_jdesc to function gfs2_evict_inode. In theory, this should only happen to corrupt gfs2 file systems, when gfs2 detects the problem, reports it, then tries to evict all the system inodes it has read in up to that point. Reported-by: Yang Lan Signed-off-by: Bob Peterson Signed-off-by: Andreas Gruenbacher --- fs/gfs2/super.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/fs/gfs2/super.c b/fs/gfs2/super.c index 5eed8c237500..a84bf6444bba 100644 --- a/fs/gfs2/super.c +++ b/fs/gfs2/super.c @@ -1419,6 +1419,14 @@ static void gfs2_evict_inode(struct inode *inode) if (inode->i_nlink || sb_rdonly(sb) || !ip->i_no_addr) goto out; + /* + * In case of an incomplete mount, gfs2_evict_inode() may be called for + * system files without having an active journal to write to. In that + * case, skip the filesystem evict. + */ + if (!sdp->sd_jdesc) + goto out; + gfs2_holder_mark_uninitialized(&gh); ret = evict_should_delete(inode, &gh); if (ret == SHOULD_DEFER_EVICTION)