[PATCH v3 3/3] udf: refactor inode_bmap() to handle error

From: Zhao Mengmeng
Date: Tue Oct 01 2024 - 07:56:43 EST


From: Zhao Mengmeng <zhaomengmeng@xxxxxxxxxx>

Refactor inode_bmap() to handle error since udf_next_aext() can return
error now. On situations like ftruncate, udf_extend_file() can now
detect errors and bail out early without resorting to checking for
particular offsets and assuming internal behavior of these functions.

Reported-by: syzbot+7a4842f0b1801230a989@xxxxxxxxxxxxxxxxxxxxxxxxx
Closes: https://syzkaller.appspot.com/bug?extid=7a4842f0b1801230a989
Tested-by: syzbot+7a4842f0b1801230a989@xxxxxxxxxxxxxxxxxxxxxxxxx
Signed-off-by: Zhao Mengmeng <zhaomengmeng@xxxxxxxxxx>
Suggested-by: Jan Kara <jack@xxxxxxx>
---
fs/udf/directory.c | 13 ++++++++-----
fs/udf/inode.c | 27 ++++++++++++++++-----------
fs/udf/partition.c | 6 ++++--
fs/udf/truncate.c | 6 ++++--
fs/udf/udfdecl.h | 5 +++--
5 files changed, 35 insertions(+), 22 deletions(-)

diff --git a/fs/udf/directory.c b/fs/udf/directory.c
index c6950050e7ae..632453aa3893 100644
--- a/fs/udf/directory.c
+++ b/fs/udf/directory.c
@@ -246,6 +246,7 @@ int udf_fiiter_init(struct udf_fileident_iter *iter, struct inode *dir,
{
struct udf_inode_info *iinfo = UDF_I(dir);
int err = 0;
+ int8_t etype;

iter->dir = dir;
iter->bh[0] = iter->bh[1] = NULL;
@@ -265,9 +266,9 @@ int udf_fiiter_init(struct udf_fileident_iter *iter, struct inode *dir,
goto out;
}

- if (inode_bmap(dir, iter->pos >> dir->i_blkbits, &iter->epos,
- &iter->eloc, &iter->elen, &iter->loffset) !=
- (EXT_RECORDED_ALLOCATED >> 30)) {
+ err = inode_bmap(dir, iter->pos >> dir->i_blkbits, &iter->epos,
+ &iter->eloc, &iter->elen, &iter->loffset, &etype);
+ if (err <= 0 || etype != (EXT_RECORDED_ALLOCATED >> 30)) {
if (pos == dir->i_size)
return 0;
udf_err(dir->i_sb,
@@ -463,6 +464,7 @@ int udf_fiiter_append_blk(struct udf_fileident_iter *iter)
sector_t block;
uint32_t old_elen = iter->elen;
int err;
+ int8_t etype;

if (WARN_ON_ONCE(iinfo->i_alloc_type == ICBTAG_FLAG_AD_IN_ICB))
return -EINVAL;
@@ -477,8 +479,9 @@ int udf_fiiter_append_blk(struct udf_fileident_iter *iter)
udf_fiiter_update_elen(iter, old_elen);
return err;
}
- if (inode_bmap(iter->dir, block, &iter->epos, &iter->eloc, &iter->elen,
- &iter->loffset) != (EXT_RECORDED_ALLOCATED >> 30)) {
+ err = inode_bmap(iter->dir, block, &iter->epos, &iter->eloc, &iter->elen,
+ &iter->loffset, &etype);
+ if (err <= 0 || etype != (EXT_RECORDED_ALLOCATED >> 30)) {
udf_err(iter->dir->i_sb,
"block %llu not allocated in directory (ino %lu)\n",
(unsigned long long)block, iter->dir->i_ino);
diff --git a/fs/udf/inode.c b/fs/udf/inode.c
index 84093f9c71c7..c275a5f3a0f6 100644
--- a/fs/udf/inode.c
+++ b/fs/udf/inode.c
@@ -418,10 +418,11 @@ static int udf_map_block(struct inode *inode, struct udf_map_rq *map)
uint32_t elen;
sector_t offset;
struct extent_position epos = {};
+ int8_t etype;

down_read(&iinfo->i_data_sem);
- if (inode_bmap(inode, map->lblk, &epos, &eloc, &elen, &offset)
- == (EXT_RECORDED_ALLOCATED >> 30)) {
+ err = inode_bmap(inode, map->lblk, &epos, &eloc, &elen, &offset, &etype);
+ if (err == 1 && etype == (EXT_RECORDED_ALLOCATED >> 30)) {
map->pblk = udf_get_lb_pblock(inode->i_sb, &eloc,
offset);
map->oflags |= UDF_BLK_MAPPED;
@@ -664,8 +665,10 @@ static int udf_extend_file(struct inode *inode, loff_t newsize)
*/
udf_discard_prealloc(inode);

- etype = inode_bmap(inode, first_block, &epos, &eloc, &elen, &offset);
- within_last_ext = (etype != -1);
+ err = inode_bmap(inode, first_block, &epos, &eloc, &elen, &offset, &etype);
+ if (err < 0)
+ goto out;
+ within_last_ext = (err == 1);
/* We don't expect extents past EOF... */
WARN_ON_ONCE(within_last_ext &&
elen > ((loff_t)offset + 1) << inode->i_blkbits);
@@ -2398,13 +2401,15 @@ int8_t udf_delete_aext(struct inode *inode, struct extent_position epos)
return (elen >> 30);
}

-int8_t inode_bmap(struct inode *inode, sector_t block,
- struct extent_position *pos, struct kernel_lb_addr *eloc,
- uint32_t *elen, sector_t *offset)
+/*
+ * Returns 1 on success, -errno on error, 0 on hit EOF.
+ */
+int inode_bmap(struct inode *inode, sector_t block, struct extent_position *pos,
+ struct kernel_lb_addr *eloc, uint32_t *elen, sector_t *offset,
+ int8_t *etype)
{
unsigned char blocksize_bits = inode->i_sb->s_blocksize_bits;
loff_t lbcount = 0, bcount = (loff_t) block << blocksize_bits;
- int8_t etype;
struct udf_inode_info *iinfo;
int err = 0;

@@ -2416,13 +2421,13 @@ int8_t inode_bmap(struct inode *inode, sector_t block,
}
*elen = 0;
do {
- err = udf_next_aext(inode, pos, eloc, elen, &etype, 1);
+ err = udf_next_aext(inode, pos, eloc, elen, etype, 1);
if (err <= 0) {
if (err == 0) {
*offset = (bcount - lbcount) >> blocksize_bits;
iinfo->i_lenExtents = lbcount;
}
- return -1;
+ return err;
}
lbcount += *elen;
} while (lbcount <= bcount);
@@ -2430,5 +2435,5 @@ int8_t inode_bmap(struct inode *inode, sector_t block,
udf_update_extent_cache(inode, lbcount - *elen, pos);
*offset = (bcount + *elen - lbcount) >> blocksize_bits;

- return etype;
+ return 1;
}
diff --git a/fs/udf/partition.c b/fs/udf/partition.c
index af877991edc1..2b85c9501bed 100644
--- a/fs/udf/partition.c
+++ b/fs/udf/partition.c
@@ -282,9 +282,11 @@ static uint32_t udf_try_read_meta(struct inode *inode, uint32_t block,
sector_t ext_offset;
struct extent_position epos = {};
uint32_t phyblock;
+ int8_t etype;
+ int err = 0;

- if (inode_bmap(inode, block, &epos, &eloc, &elen, &ext_offset) !=
- (EXT_RECORDED_ALLOCATED >> 30))
+ err = inode_bmap(inode, block, &epos, &eloc, &elen, &ext_offset, &etype);
+ if (err <= 0 || etype != (EXT_RECORDED_ALLOCATED >> 30))
phyblock = 0xFFFFFFFF;
else {
map = &UDF_SB(sb)->s_partmaps[partition];
diff --git a/fs/udf/truncate.c b/fs/udf/truncate.c
index b91876a7b53a..03774282361b 100644
--- a/fs/udf/truncate.c
+++ b/fs/udf/truncate.c
@@ -210,10 +210,12 @@ int udf_truncate_extents(struct inode *inode)
else
BUG();

- etype = inode_bmap(inode, first_block, &epos, &eloc, &elen, &offset);
+ err = inode_bmap(inode, first_block, &epos, &eloc, &elen, &offset, &etype);
byte_offset = (offset << sb->s_blocksize_bits) +
(inode->i_size & (sb->s_blocksize - 1));
- if (etype == -1) {
+ if (err < 0)
+ return err;
+ else if (err == 0) {
/* We should extend the file? */
WARN_ON(byte_offset);
return 0;
diff --git a/fs/udf/udfdecl.h b/fs/udf/udfdecl.h
index 5067ed68a8b4..d159f20d61e8 100644
--- a/fs/udf/udfdecl.h
+++ b/fs/udf/udfdecl.h
@@ -157,8 +157,9 @@ extern struct buffer_head *udf_bread(struct inode *inode, udf_pblk_t block,
extern int udf_setsize(struct inode *, loff_t);
extern void udf_evict_inode(struct inode *);
extern int udf_write_inode(struct inode *, struct writeback_control *wbc);
-extern int8_t inode_bmap(struct inode *, sector_t, struct extent_position *,
- struct kernel_lb_addr *, uint32_t *, sector_t *);
+extern int inode_bmap(struct inode *inode, sector_t block,
+ struct extent_position *pos, struct kernel_lb_addr *eloc,
+ uint32_t *elen, sector_t *offset, int8_t *etype);
int udf_get_block(struct inode *, sector_t, struct buffer_head *, int);
extern int udf_setup_indirect_aext(struct inode *inode, udf_pblk_t block,
struct extent_position *epos);
--
2.43.0