4.18-stable review patch. If anyone has any objections, please let me know.
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From: Jan Kara jack@suse.cz
[ Upstream commit a9ad01bc759df79b0012f43ee52164391e31cd96 ]
There are certain filesystem features which we support for reading but not for writing. We properly refuse to mount such filesystems read-write however for some features (such as read-only partitions), we don't check for these features when remounting the filesystem from read-only to read-write. Thus such filesystems could be remounted read-write leading to strange behavior (most likely crashes).
Fix the problem by marking in superblock whether the filesystem has some features that are supported in read-only mode and check this flag during remount.
Signed-off-by: Jan Kara jack@suse.cz Signed-off-by: Sasha Levin sashal@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- fs/udf/super.c | 30 ++++++++++++++++-------------- fs/udf/udf_sb.h | 2 ++ 2 files changed, 18 insertions(+), 14 deletions(-)
--- a/fs/udf/super.c +++ b/fs/udf/super.c @@ -613,14 +613,11 @@ static int udf_remount_fs(struct super_b struct udf_options uopt; struct udf_sb_info *sbi = UDF_SB(sb); int error = 0; - struct logicalVolIntegrityDescImpUse *lvidiu = udf_sb_lvidiu(sb); + + if (!(*flags & SB_RDONLY) && UDF_QUERY_FLAG(sb, UDF_FLAG_RW_INCOMPAT)) + return -EACCES;
sync_filesystem(sb); - if (lvidiu) { - int write_rev = le16_to_cpu(lvidiu->minUDFWriteRev); - if (write_rev > UDF_MAX_WRITE_VERSION && !(*flags & SB_RDONLY)) - return -EACCES; - }
uopt.flags = sbi->s_flags; uopt.uid = sbi->s_uid; @@ -1317,6 +1314,7 @@ static int udf_load_partdesc(struct supe ret = -EACCES; goto out_bh; } + UDF_SET_FLAG(sb, UDF_FLAG_RW_INCOMPAT); ret = udf_load_vat(sb, i, type1_idx); if (ret < 0) goto out_bh; @@ -2215,10 +2213,12 @@ static int udf_fill_super(struct super_b UDF_MAX_READ_VERSION); ret = -EINVAL; goto error_out; - } else if (minUDFWriteRev > UDF_MAX_WRITE_VERSION && - !sb_rdonly(sb)) { - ret = -EACCES; - goto error_out; + } else if (minUDFWriteRev > UDF_MAX_WRITE_VERSION) { + if (!sb_rdonly(sb)) { + ret = -EACCES; + goto error_out; + } + UDF_SET_FLAG(sb, UDF_FLAG_RW_INCOMPAT); }
sbi->s_udfrev = minUDFWriteRev; @@ -2236,10 +2236,12 @@ static int udf_fill_super(struct super_b }
if (sbi->s_partmaps[sbi->s_partition].s_partition_flags & - UDF_PART_FLAG_READ_ONLY && - !sb_rdonly(sb)) { - ret = -EACCES; - goto error_out; + UDF_PART_FLAG_READ_ONLY) { + if (!sb_rdonly(sb)) { + ret = -EACCES; + goto error_out; + } + UDF_SET_FLAG(sb, UDF_FLAG_RW_INCOMPAT); }
if (udf_find_fileset(sb, &fileset, &rootdir)) { --- a/fs/udf/udf_sb.h +++ b/fs/udf/udf_sb.h @@ -30,6 +30,8 @@ #define UDF_FLAG_LASTBLOCK_SET 16 #define UDF_FLAG_BLOCKSIZE_SET 17 #define UDF_FLAG_INCONSISTENT 18 +#define UDF_FLAG_RW_INCOMPAT 19 /* Set when we find RW incompatible + * feature */
#define UDF_PART_FLAG_UNALLOC_BITMAP 0x0001 #define UDF_PART_FLAG_UNALLOC_TABLE 0x0002