[PATCH AUTOSEL 6.5 04/11] ext4: add two helper functions extent_logical_end() and pa_logical_end()

[PATCH AUTOSEL 6.5 04/11] ext4: add two helper functions extent_logical_end() and pa_logical_end()

[Sasha Levin]

From: Baokun Li <libaokun1@huawei.com>

[ Upstream commit 43bbddc067883d94de7a43d5756a295439fbe37d ]

When we use lstart + len to calculate the end of free extent or prealloc
space, it may exceed the maximum value of 4294967295(0xffffffff) supported
by ext4_lblk_t and cause overflow, which may lead to various problems.

Therefore, we add two helper functions, extent_logical_end() and
pa_logical_end(), to limit the type of end to loff_t, and also convert
lstart to loff_t for calculation to avoid overflow.

Signed-off-by: Baokun Li <libaokun1@huawei.com>
Reviewed-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com>
Link: https://lore.kernel.org/r/20230724121059.11834-2-libaokun1@huawei.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 fs/ext4/mballoc.c |  9 +++------
 fs/ext4/mballoc.h | 14 ++++++++++++++
 2 files changed, 17 insertions(+), 6 deletions(-)

diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
index 21b903fe546e8..4cb13b3e41b3f 100644
--- a/fs/ext4/mballoc.c
+++ b/fs/ext4/mballoc.c
@@ -4432,7 +4432,7 @@ ext4_mb_normalize_request(struct ext4_allocation_context *ac,
 
 	/* first, let's learn actual file size
 	 * given current request is allocated */
-	size = ac->ac_o_ex.fe_logical + EXT4_C2B(sbi, ac->ac_o_ex.fe_len);
+	size = extent_logical_end(sbi, &ac->ac_o_ex);
 	size = size << bsbits;
 	if (size < i_size_read(ac->ac_inode))
 		size = i_size_read(ac->ac_inode);
@@ -4766,7 +4766,6 @@ ext4_mb_use_preallocated(struct ext4_allocation_context *ac)
 	struct ext4_inode_info *ei = EXT4_I(ac->ac_inode);
 	struct ext4_locality_group *lg;
 	struct ext4_prealloc_space *tmp_pa = NULL, *cpa = NULL;
-	loff_t tmp_pa_end;
 	struct rb_node *iter;
 	ext4_fsblk_t goal_block;
 
@@ -4862,9 +4861,7 @@ ext4_mb_use_preallocated(struct ext4_allocation_context *ac)
 	 * pa can possibly satisfy the request hence check if it overlaps
 	 * original logical start and stop searching if it doesn't.
 	 */
-	tmp_pa_end = (loff_t)tmp_pa->pa_lstart + EXT4_C2B(sbi, tmp_pa->pa_len);
-
-	if (ac->ac_o_ex.fe_logical >= tmp_pa_end) {
+	if (ac->ac_o_ex.fe_logical >= pa_logical_end(sbi, tmp_pa)) {
 		spin_unlock(&tmp_pa->pa_lock);
 		goto try_group_pa;
 	}
@@ -5769,7 +5766,7 @@ static void ext4_mb_group_or_file(struct ext4_allocation_context *ac)
 
 	group_pa_eligible = sbi->s_mb_group_prealloc > 0;
 	inode_pa_eligible = true;
-	size = ac->ac_o_ex.fe_logical + EXT4_C2B(sbi, ac->ac_o_ex.fe_len);
+	size = extent_logical_end(sbi, &ac->ac_o_ex);
 	isize = (i_size_read(ac->ac_inode) + ac->ac_sb->s_blocksize - 1)
 		>> bsbits;
 
diff --git a/fs/ext4/mballoc.h b/fs/ext4/mballoc.h
index df6b5e7c22741..d7aeb5da7d867 100644
--- a/fs/ext4/mballoc.h
+++ b/fs/ext4/mballoc.h
@@ -233,6 +233,20 @@ static inline ext4_fsblk_t ext4_grp_offs_to_block(struct super_block *sb,
 		(fex->fe_start << EXT4_SB(sb)->s_cluster_bits);
 }
 
+static inline loff_t extent_logical_end(struct ext4_sb_info *sbi,
+					struct ext4_free_extent *fex)
+{
+	/* Use loff_t to avoid end exceeding ext4_lblk_t max. */
+	return (loff_t)fex->fe_logical + EXT4_C2B(sbi, fex->fe_len);
+}
+
+static inline loff_t pa_logical_end(struct ext4_sb_info *sbi,
+				    struct ext4_prealloc_space *pa)
+{
+	/* Use loff_t to avoid end exceeding ext4_lblk_t max. */
+	return (loff_t)pa->pa_lstart + EXT4_C2B(sbi, pa->pa_len);
+}
+
 typedef int (*ext4_mballoc_query_range_fn)(
 	struct super_block		*sb,
 	ext4_group_t			agno,
-- 
2.40.1

[PATCH AUTOSEL 6.5 05/11] ext4: avoid overlapping preallocations due to overflow

[Sasha Levin]

From: Baokun Li <libaokun1@huawei.com>

[ Upstream commit bedc5d34632c21b5adb8ca7143d4c1f794507e4c ]

Let's say we want to allocate 2 blocks starting from 4294966386, after
predicting the file size, start is aligned to 4294965248, len is changed
to 2048, then end = start + size = 0x100000000. Since end is of
type ext4_lblk_t, i.e. uint, end is truncated to 0.

This causes (pa->pa_lstart >= end) to always hold when checking if the
current extent to be allocated crosses already preallocated blocks, so the
resulting ac_g_ex may cross already preallocated blocks. Hence we convert
the end type to loff_t and use pa_logical_end() to avoid overflow.

Signed-off-by: Baokun Li <libaokun1@huawei.com>
Reviewed-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com>
Link: https://lore.kernel.org/r/20230724121059.11834-4-libaokun1@huawei.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 fs/ext4/mballoc.c | 21 ++++++++++-----------
 1 file changed, 10 insertions(+), 11 deletions(-)

diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
index 4cb13b3e41b3f..2fdcd37b7c54f 100644
--- a/fs/ext4/mballoc.c
+++ b/fs/ext4/mballoc.c
@@ -4222,12 +4222,13 @@ ext4_mb_pa_rb_next_iter(ext4_lblk_t new_start, ext4_lblk_t cur_start, struct rb_
 
 static inline void
 ext4_mb_pa_assert_overlap(struct ext4_allocation_context *ac,
-			  ext4_lblk_t start, ext4_lblk_t end)
+			  ext4_lblk_t start, loff_t end)
 {
 	struct ext4_sb_info *sbi = EXT4_SB(ac->ac_sb);
 	struct ext4_inode_info *ei = EXT4_I(ac->ac_inode);
 	struct ext4_prealloc_space *tmp_pa;
-	ext4_lblk_t tmp_pa_start, tmp_pa_end;
+	ext4_lblk_t tmp_pa_start;
+	loff_t tmp_pa_end;
 	struct rb_node *iter;
 
 	read_lock(&ei->i_prealloc_lock);
@@ -4236,7 +4237,7 @@ ext4_mb_pa_assert_overlap(struct ext4_allocation_context *ac,
 		tmp_pa = rb_entry(iter, struct ext4_prealloc_space,
 				  pa_node.inode_node);
 		tmp_pa_start = tmp_pa->pa_lstart;
-		tmp_pa_end = tmp_pa->pa_lstart + EXT4_C2B(sbi, tmp_pa->pa_len);
+		tmp_pa_end = pa_logical_end(sbi, tmp_pa);
 
 		spin_lock(&tmp_pa->pa_lock);
 		if (tmp_pa->pa_deleted == 0)
@@ -4258,14 +4259,14 @@ ext4_mb_pa_assert_overlap(struct ext4_allocation_context *ac,
  */
 static inline void
 ext4_mb_pa_adjust_overlap(struct ext4_allocation_context *ac,
-			  ext4_lblk_t *start, ext4_lblk_t *end)
+			  ext4_lblk_t *start, loff_t *end)
 {
 	struct ext4_inode_info *ei = EXT4_I(ac->ac_inode);
 	struct ext4_sb_info *sbi = EXT4_SB(ac->ac_sb);
 	struct ext4_prealloc_space *tmp_pa = NULL, *left_pa = NULL, *right_pa = NULL;
 	struct rb_node *iter;
-	ext4_lblk_t new_start, new_end;
-	ext4_lblk_t tmp_pa_start, tmp_pa_end, left_pa_end = -1, right_pa_start = -1;
+	ext4_lblk_t new_start, tmp_pa_start, right_pa_start = -1;
+	loff_t new_end, tmp_pa_end, left_pa_end = -1;
 
 	new_start = *start;
 	new_end = *end;
@@ -4284,7 +4285,7 @@ ext4_mb_pa_adjust_overlap(struct ext4_allocation_context *ac,
 		tmp_pa = rb_entry(iter, struct ext4_prealloc_space,
 				  pa_node.inode_node);
 		tmp_pa_start = tmp_pa->pa_lstart;
-		tmp_pa_end = tmp_pa->pa_lstart + EXT4_C2B(sbi, tmp_pa->pa_len);
+		tmp_pa_end = pa_logical_end(sbi, tmp_pa);
 
 		/* PA must not overlap original request */
 		spin_lock(&tmp_pa->pa_lock);
@@ -4364,8 +4365,7 @@ ext4_mb_pa_adjust_overlap(struct ext4_allocation_context *ac,
 	}
 
 	if (left_pa) {
-		left_pa_end =
-			left_pa->pa_lstart + EXT4_C2B(sbi, left_pa->pa_len);
+		left_pa_end = pa_logical_end(sbi, left_pa);
 		BUG_ON(left_pa_end > ac->ac_o_ex.fe_logical);
 	}
 
@@ -4404,8 +4404,7 @@ ext4_mb_normalize_request(struct ext4_allocation_context *ac,
 	struct ext4_sb_info *sbi = EXT4_SB(ac->ac_sb);
 	struct ext4_super_block *es = sbi->s_es;
 	int bsbits, max;
-	ext4_lblk_t end;
-	loff_t size, start_off;
+	loff_t size, start_off, end;
 	loff_t orig_size __maybe_unused;
 	ext4_lblk_t start;
 
-- 
2.40.1