[PATCH 5.10 014/236] udf: Check LVID earlier

Greg Kroah-Hartman
2021-09-13T13:34:51Z

From: Jan Kara <jack@suse.cz>

[ Upstream commit 781d2a9a2fc7d0be53a072794dc03ef6de770f3d ]

We were checking validity of LVID entries only when getting
implementation use information from LVID in udf_sb_lvidiu(). However if
the LVID is suitably corrupted, it can cause problems also to code such
as udf_count_free() which doesn't use udf_sb_lvidiu(). So check validity
of LVID already when loading it from the disk and just disable LVID
altogether when it is not valid.

Reported-by: syzbot+7fbfe5fed73ebb675748@syzkaller.appspotmail.com
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
fs/udf/super.c | 25 ++++++++++++++++---------
1 file changed, 16 insertions(+), 9 deletions(-)

diff --git a/fs/udf/super.c b/fs/udf/super.c
index d0df217f4712..a59bf469dd1c 100644
--- a/fs/udf/super.c
+++ b/fs/udf/super.c
@@ -108,16 +108,10 @@ struct logicalVolIntegrityDescImpUse *udf_sb_lvidiu(struct super_block *sb)
return NULL;
lvid = (struct logicalVolIntegrityDesc *)UDF_SB(sb)->s_lvid_bh->b_data;
partnum = le32_to_cpu(lvid->numOfPartitions);
- if ((sb->s_blocksize - sizeof(struct logicalVolIntegrityDescImpUse) -
- offsetof(struct logicalVolIntegrityDesc, impUse)) /
- (2 * sizeof(uint32_t)) < partnum) {
- udf_err(sb, "Logical volume integrity descriptor corrupted "
- "(numOfPartitions = %u)!\n", partnum);
- return NULL;
- }
/* The offset is to skip freeSpaceTable and sizeTable arrays */
offset = partnum * 2 * sizeof(uint32_t);
- return (struct logicalVolIntegrityDescImpUse *)&(lvid->impUse[offset]);
+ return (struct logicalVolIntegrityDescImpUse *)
+ (((uint8_t *)(lvid + 1)) + offset);
}

/* UDF filesystem type */
@@ -1541,6 +1535,7 @@ static void udf_load_logicalvolint(struct super_block *sb, struct kernel_extent_
struct udf_sb_info *sbi = UDF_SB(sb);
struct logicalVolIntegrityDesc *lvid;
int indirections = 0;
+ u32 parts, impuselen;

while (++indirections <= UDF_MAX_LVID_NESTING) {
final_bh = NULL;
@@ -1567,15 +1562,27 @@ static void udf_load_logicalvolint(struct super_block *sb, struct kernel_extent_

lvid = (struct logicalVolIntegrityDesc *)final_bh->b_data;
if (lvid->nextIntegrityExt.extLength == 0)
- return;
+ goto check;

loc = leea_to_cpu(lvid->nextIntegrityExt);
}

udf_warn(sb, "Too many LVID indirections (max %u), ignoring.\n",
UDF_MAX_LVID_NESTING);
+out_err:
brelse(sbi->s_lvid_bh);
sbi->s_lvid_bh = NULL;
+ return;
+check:
+ parts = le32_to_cpu(lvid->numOfPartitions);
+ impuselen = le32_to_cpu(lvid->lengthOfImpUse);
+ if (parts >= sb->s_blocksize || impuselen >= sb->s_blocksize ||
+ sizeof(struct logicalVolIntegrityDesc) + impuselen +
+ 2 * parts * sizeof(u32) > sb->s_blocksize) {
+ udf_warn(sb, "Corrupted LVID (parts=%u, impuselen=%u), "
+ "ignoring.\n", parts, impuselen);
+ goto out_err;
+ }
}

/*
--
2.30.2