[PATCH 6.6.y] gfs2: reject invalid inode sizes

[Sasha Levin <sashal@kernel.org>]

From: Jiaming Zhang <r772577952@gmail.com>

[ Upstream commit 33ed0a0567e0abe66ea65e89dad2e35082890fbe ]

A corrupted GFS2 image can store a dinode size that is larger than what VFS
i_size can represent. gfs2_dinode_in() reads the on-disk di_size as a u64 and
writes it directly into inode->i_size. If the value is larger than S64_MAX, the
incore i_size becomes negative. That negative value can bypass the existing
stuffed inode size check:

inode->i_size > gfs2_max_stuffed_size(ip)

Later, gfs2_quotad may try to sync the quota file and unstuff the quota inode.
gfs2_unstuffer_folio() reads the negative i_size into an unsigned length and
passes it to memcpy(), turning it into a huge copy size and triggering a
out-of-bound issue.

Reject dinodes whose size exceeds sb->s_maxbytes before storing the value in
inode->i_size. Also make the stuffed inode check use the raw on-disk size while
it is still unsigned.

Fixes: 70376c7ff312 ("gfs2: Always check inode size of inline inodes")
Closes: https://lore.kernel.org/lkml/CANypQFaF6bvORKKbRALvEL0k_epFaneFiOQqco4gjdmKVbdURg@mail.gmail.com/
Assisted-by: Codex:gpt-5.5-xhigh
Cc: stable@vger.kernel.org
Signed-off-by: Jiaming Zhang <r772577952@gmail.com>
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
[ sashal: adjusted context for direct inode->i_state access instead of inode_state_read_once() ]
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 fs/gfs2/glops.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/fs/gfs2/glops.c b/fs/gfs2/glops.c
index f575cd8ff47c1..0be93498e3308 100644
--- a/fs/gfs2/glops.c
+++ b/fs/gfs2/glops.c
@@ -412,6 +412,7 @@ static int gfs2_dinode_in(struct gfs2_inode *ip, const void *buf)
 	umode_t mode = be32_to_cpu(str->di_mode);
 	struct inode *inode = &ip->i_inode;
 	bool is_new = inode->i_state & I_NEW;
+	u64 size;
 
 	if (unlikely(ip->i_no_addr != be64_to_cpu(str->di_num.no_addr))) {
 		gfs2_consist_inode(ip);
@@ -437,7 +438,12 @@ static int gfs2_dinode_in(struct gfs2_inode *ip, const void *buf)
 	i_uid_write(inode, be32_to_cpu(str->di_uid));
 	i_gid_write(inode, be32_to_cpu(str->di_gid));
 	set_nlink(inode, be32_to_cpu(str->di_nlink));
-	i_size_write(inode, be64_to_cpu(str->di_size));
+	size = be64_to_cpu(str->di_size);
+	if (unlikely(size > inode->i_sb->s_maxbytes)) {
+		gfs2_consist_inode(ip);
+		return -EIO;
+	}
+	i_size_write(inode, size);
 	gfs2_set_inode_blocks(inode, be64_to_cpu(str->di_blocks));
 	atime.tv_sec = be64_to_cpu(str->di_atime);
 	atime.tv_nsec = be32_to_cpu(str->di_atime_nsec);
@@ -475,7 +481,7 @@ static int gfs2_dinode_in(struct gfs2_inode *ip, const void *buf)
 	ip->i_depth = (u8)depth;
 	ip->i_entries = be32_to_cpu(str->di_entries);
 
-	if (gfs2_is_stuffed(ip) && inode->i_size > gfs2_max_stuffed_size(ip)) {
+	if (gfs2_is_stuffed(ip) && size > gfs2_max_stuffed_size(ip)) {
 		gfs2_consist_inode(ip);
 		return -EIO;
 	}
-- 
2.53.0