linux-kernel - [PATCH AUTOSEL 5.4 39/80] udf: Avoid accessing uninitialized data on failed inode read

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Message-Id: <20201018192231.4054535-39-sashal@kernel.org>
Date:   Sun, 18 Oct 2020 15:21:50 -0400
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Jan Kara <jack@...e.cz>,
        syzbot+91f02b28f9bb5f5f1341@...kaller.appspotmail.com,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH AUTOSEL 5.4 39/80] udf: Avoid accessing uninitialized data on failed inode read

From: Jan Kara <jack@...e.cz>

[ Upstream commit 044e2e26f214e5ab26af85faffd8d1e4ec066931 ]

When we fail to read inode, some data accessed in udf_evict_inode() may
be uninitialized. Move the accesses to !is_bad_inode() branch.

Reported-by: syzbot+91f02b28f9bb5f5f1341@...kaller.appspotmail.com
Signed-off-by: Jan Kara <jack@...e.cz>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 fs/udf/inode.c | 25 ++++++++++++++-----------
 1 file changed, 14 insertions(+), 11 deletions(-)

diff --git a/fs/udf/inode.c b/fs/udf/inode.c
index ea80036d7897b..97a192eb9949c 100644
--- a/fs/udf/inode.c
+++ b/fs/udf/inode.c
@@ -139,21 +139,24 @@ void udf_evict_inode(struct inode *inode)
 	struct udf_inode_info *iinfo = UDF_I(inode);
 	int want_delete = 0;
 
-	if (!inode->i_nlink && !is_bad_inode(inode)) {
-		want_delete = 1;
-		udf_setsize(inode, 0);
-		udf_update_inode(inode, IS_SYNC(inode));
+	if (!is_bad_inode(inode)) {
+		if (!inode->i_nlink) {
+			want_delete = 1;
+			udf_setsize(inode, 0);
+			udf_update_inode(inode, IS_SYNC(inode));
+		}
+		if (iinfo->i_alloc_type != ICBTAG_FLAG_AD_IN_ICB &&
+		    inode->i_size != iinfo->i_lenExtents) {
+			udf_warn(inode->i_sb,
+				 "Inode %lu (mode %o) has inode size %llu different from extent length %llu. Filesystem need not be standards compliant.\n",
+				 inode->i_ino, inode->i_mode,
+				 (unsigned long long)inode->i_size,
+				 (unsigned long long)iinfo->i_lenExtents);
+		}
 	}
 	truncate_inode_pages_final(&inode->i_data);
 	invalidate_inode_buffers(inode);
 	clear_inode(inode);
-	if (iinfo->i_alloc_type != ICBTAG_FLAG_AD_IN_ICB &&
-	    inode->i_size != iinfo->i_lenExtents) {
-		udf_warn(inode->i_sb, "Inode %lu (mode %o) has inode size %llu different from extent length %llu. Filesystem need not be standards compliant.\n",
-			 inode->i_ino, inode->i_mode,
-			 (unsigned long long)inode->i_size,
-			 (unsigned long long)iinfo->i_lenExtents);
-	}
 	kfree(iinfo->i_ext.i_data);
 	iinfo->i_ext.i_data = NULL;
 	udf_clear_extent_cache(inode);
-- 
2.25.1