treewide: Change list_sort to use const pointers

list_sort() internally casts the comparison function passed to it
to a different type with constant struct list_head pointers, and
uses this pointer to call the functions, which trips indirect call
Control-Flow Integrity (CFI) checking.

Instead of removing the consts, this change defines the
list_cmp_func_t type and changes the comparison function types of
all list_sort() callers to use const pointers, thus avoiding type
mismatches.

Suggested-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Kees Cook <keescook@chromium.org>
Tested-by: Nick Desaulniers <ndesaulniers@google.com>
Tested-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20210408182843.1754385-10-samitolvanen@google.com

18 files changed, 38 insertions, 30 deletions

diff --git a/fs/btrfs/raid56.c b/fs/btrfs/raid56.c
index 8c31357f08ed..f4139de63b2e 100644
--- a/fs/btrfs/raid56.c
+++ b/fs/btrfs/raid56.c
@@ -1634,7 +1634,8 @@ struct btrfs_plug_cb {
 /*
  * rbios on the plug list are sorted for easier merging.
  */
-static int plug_cmp(void *priv, struct list_head *a, struct list_head *b)
+static int plug_cmp(void *priv, const struct list_head *a,
+		    const struct list_head *b)
 {
 	struct btrfs_raid_bio *ra = container_of(a, struct btrfs_raid_bio,
 						 plug_list);
diff --git a/fs/btrfs/tree-log.c b/fs/btrfs/tree-log.c
index 92a368627791..00a88bd8105e 100644
--- a/fs/btrfs/tree-log.c
+++ b/fs/btrfs/tree-log.c
@@ -4136,7 +4136,8 @@ static noinline int copy_items(struct btrfs_trans_handle *trans,
 	return ret;
 }
 
-static int extent_cmp(void *priv, struct list_head *a, struct list_head *b)
+static int extent_cmp(void *priv, const struct list_head *a,
+		      const struct list_head *b)
 {
 	struct extent_map *em1, *em2;
 
diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 1c6810bbaf8b..912dd8b9f156 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -1224,7 +1224,8 @@ static int open_fs_devices(struct btrfs_fs_devices *fs_devices,
 	return 0;
 }
 
-static int devid_cmp(void *priv, struct list_head *a, struct list_head *b)
+static int devid_cmp(void *priv, const struct list_head *a,
+		     const struct list_head *b)
 {
 	struct btrfs_device *dev1, *dev2;
 
diff --git a/fs/ext4/fsmap.c b/fs/ext4/fsmap.c
index 4c2a9fe30067..4493ef0c715e 100644
--- a/fs/ext4/fsmap.c
+++ b/fs/ext4/fsmap.c
@@ -354,8 +354,8 @@ static unsigned int ext4_getfsmap_find_sb(struct super_block *sb,
 
 /* Compare two fsmap items. */
 static int ext4_getfsmap_compare(void *priv,
-				 struct list_head *a,
-				 struct list_head *b)
+				 const struct list_head *a,
+				 const struct list_head *b)
 {
 	struct ext4_fsmap *fa;
 	struct ext4_fsmap *fb;
diff --git a/fs/gfs2/glock.c b/fs/gfs2/glock.c
index 9567520d79f7..c06a6cdf05de 100644
--- a/fs/gfs2/glock.c
+++ b/fs/gfs2/glock.c
@@ -1732,7 +1732,8 @@ void gfs2_glock_complete(struct gfs2_glock *gl, int ret)
 	spin_unlock(&gl->gl_lockref.lock);
 }
 
-static int glock_cmp(void *priv, struct list_head *a, struct list_head *b)
+static int glock_cmp(void *priv, const struct list_head *a,
+		     const struct list_head *b)
 {
 	struct gfs2_glock *gla, *glb;
 
diff --git a/fs/gfs2/log.c b/fs/gfs2/log.c
index 6410281546f9..88649b43fcff 100644
--- a/fs/gfs2/log.c
+++ b/fs/gfs2/log.c
@@ -695,7 +695,7 @@ void log_flush_wait(struct gfs2_sbd *sdp)
 	}
 }
 
-static int ip_cmp(void *priv, struct list_head *a, struct list_head *b)
+static int ip_cmp(void *priv, const struct list_head *a, const struct list_head *b)
 {
 	struct gfs2_inode *ipa, *ipb;
 
diff --git a/fs/gfs2/lops.c b/fs/gfs2/lops.c
index a82f4747aa8d..b4809967efc6 100644
--- a/fs/gfs2/lops.c
+++ b/fs/gfs2/lops.c
@@ -634,7 +634,8 @@ static void gfs2_check_magic(struct buffer_head *bh)
 	kunmap_atomic(kaddr);
 }
 
-static int blocknr_cmp(void *priv, struct list_head *a, struct list_head *b)
+static int blocknr_cmp(void *priv, const struct list_head *a,
+		       const struct list_head *b)
 {
 	struct gfs2_bufdata *bda, *bdb;
 
diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c
index 414769a6ad11..0129e6bab985 100644
--- a/fs/iomap/buffered-io.c
+++ b/fs/iomap/buffered-io.c
@@ -1155,7 +1155,8 @@ iomap_ioend_try_merge(struct iomap_ioend *ioend, struct list_head *more_ioends,
 EXPORT_SYMBOL_GPL(iomap_ioend_try_merge);
 
 static int
-iomap_ioend_compare(void *priv, struct list_head *a, struct list_head *b)
+iomap_ioend_compare(void *priv, const struct list_head *a,
+		const struct list_head *b)
 {
 	struct iomap_ioend *ia = container_of(a, struct iomap_ioend, io_list);
 	struct iomap_ioend *ib = container_of(b, struct iomap_ioend, io_list);
diff --git a/fs/ubifs/gc.c b/fs/ubifs/gc.c
index a4aaeea63893..dc3e26e9ed7b 100644
--- a/fs/ubifs/gc.c
+++ b/fs/ubifs/gc.c
@@ -102,7 +102,8 @@ static int switch_gc_head(struct ubifs_info *c)
  * This function compares data nodes @a and @b. Returns %1 if @a has greater
  * inode or block number, and %-1 otherwise.
  */
-static int data_nodes_cmp(void *priv, struct list_head *a, struct list_head *b)
+static int data_nodes_cmp(void *priv, const struct list_head *a,
+			  const struct list_head *b)
 {
 	ino_t inuma, inumb;
 	struct ubifs_info *c = priv;
@@ -145,8 +146,8 @@ static int data_nodes_cmp(void *priv, struct list_head *a, struct list_head *b)
  * first and sorted by length in descending order. Directory entry nodes go
  * after inode nodes and are sorted in ascending hash valuer order.
  */
-static int nondata_nodes_cmp(void *priv, struct list_head *a,
-			     struct list_head *b)
+static int nondata_nodes_cmp(void *priv, const struct list_head *a,
+			     const struct list_head *b)
 {
 	ino_t inuma, inumb;
 	struct ubifs_info *c = priv;
diff --git a/fs/ubifs/replay.c b/fs/ubifs/replay.c
index 0f8a6a16421b..4d17e5382b74 100644
--- a/fs/ubifs/replay.c
+++ b/fs/ubifs/replay.c
@@ -298,8 +298,8 @@ static int apply_replay_entry(struct ubifs_info *c, struct replay_entry *r)
  * entries @a and @b by comparing their sequence numer.  Returns %1 if @a has
  * greater sequence number and %-1 otherwise.
  */
-static int replay_entries_cmp(void *priv, struct list_head *a,
-			      struct list_head *b)
+static int replay_entries_cmp(void *priv, const struct list_head *a,
+			      const struct list_head *b)
 {
 	struct ubifs_info *c = priv;
 	struct replay_entry *ra, *rb;
diff --git a/fs/xfs/scrub/bitmap.c b/fs/xfs/scrub/bitmap.c
index f88694f22d05..813b5f219113 100644
--- a/fs/xfs/scrub/bitmap.c
+++ b/fs/xfs/scrub/bitmap.c
@@ -63,8 +63,8 @@ xbitmap_init(
 static int
 xbitmap_range_cmp(
 	void			*priv,
-	struct list_head	*a,
-	struct list_head	*b)
+	const struct list_head	*a,
+	const struct list_head	*b)
 {
 	struct xbitmap_range	*ap;
 	struct xbitmap_range	*bp;
diff --git a/fs/xfs/xfs_bmap_item.c b/fs/xfs/xfs_bmap_item.c
index 2344757ede63..e3a691937e92 100644
--- a/fs/xfs/xfs_bmap_item.c
+++ b/fs/xfs/xfs_bmap_item.c
@@ -265,8 +265,8 @@ xfs_trans_log_finish_bmap_update(
 static int
 xfs_bmap_update_diff_items(
 	void				*priv,
-	struct list_head		*a,
-	struct list_head		*b)
+	const struct list_head		*a,
+	const struct list_head		*b)
 {
 	struct xfs_bmap_intent		*ba;
 	struct xfs_bmap_intent		*bb;
diff --git a/fs/xfs/xfs_buf.c b/fs/xfs/xfs_buf.c
index 37a1d12762d8..592800c8852f 100644
--- a/fs/xfs/xfs_buf.c
+++ b/fs/xfs/xfs_buf.c
@@ -2124,9 +2124,9 @@ xfs_buf_delwri_queue(
  */
 static int
 xfs_buf_cmp(
-	void		*priv,
-	struct list_head *a,
-	struct list_head *b)
+	void			*priv,
+	const struct list_head	*a,
+	const struct list_head	*b)
 {
 	struct xfs_buf	*ap = container_of(a, struct xfs_buf, b_list);
 	struct xfs_buf	*bp = container_of(b, struct xfs_buf, b_list);
diff --git a/fs/xfs/xfs_extent_busy.c b/fs/xfs/xfs_extent_busy.c
index ef17c1f6db32..a4075685d9eb 100644
--- a/fs/xfs/xfs_extent_busy.c
+++ b/fs/xfs/xfs_extent_busy.c
@@ -629,8 +629,8 @@ xfs_extent_busy_wait_all(
 int
 xfs_extent_busy_ag_cmp(
 	void			*priv,
-	struct list_head	*l1,
-	struct list_head	*l2)
+	const struct list_head	*l1,
+	const struct list_head	*l2)
 {
 	struct xfs_extent_busy	*b1 =
 		container_of(l1, struct xfs_extent_busy, list);
diff --git a/fs/xfs/xfs_extent_busy.h b/fs/xfs/xfs_extent_busy.h
index 990ab3891971..8aea07100092 100644
--- a/fs/xfs/xfs_extent_busy.h
+++ b/fs/xfs/xfs_extent_busy.h
@@ -58,7 +58,8 @@ void
 xfs_extent_busy_wait_all(struct xfs_mount *mp);
 
 int
-xfs_extent_busy_ag_cmp(void *priv, struct list_head *a, struct list_head *b);
+xfs_extent_busy_ag_cmp(void *priv, const struct list_head *a,
+	const struct list_head *b);
 
 static inline void xfs_extent_busy_sort(struct list_head *list)
 {
diff --git a/fs/xfs/xfs_extfree_item.c b/fs/xfs/xfs_extfree_item.c
index 93223ebb3372..2424230ca2c3 100644
--- a/fs/xfs/xfs_extfree_item.c
+++ b/fs/xfs/xfs_extfree_item.c
@@ -397,8 +397,8 @@ xfs_trans_free_extent(
 static int
 xfs_extent_free_diff_items(
 	void				*priv,
-	struct list_head		*a,
-	struct list_head		*b)
+	const struct list_head		*a,
+	const struct list_head		*b)
 {
 	struct xfs_mount		*mp = priv;
 	struct xfs_extent_free_item	*ra;
diff --git a/fs/xfs/xfs_refcount_item.c b/fs/xfs/xfs_refcount_item.c
index 07ebccbbf4df..746f4eda724c 100644
--- a/fs/xfs/xfs_refcount_item.c
+++ b/fs/xfs/xfs_refcount_item.c
@@ -269,8 +269,8 @@ xfs_trans_log_finish_refcount_update(
 static int
 xfs_refcount_update_diff_items(
 	void				*priv,
-	struct list_head		*a,
-	struct list_head		*b)
+	const struct list_head		*a,
+	const struct list_head		*b)
 {
 	struct xfs_mount		*mp = priv;
 	struct xfs_refcount_intent	*ra;
diff --git a/fs/xfs/xfs_rmap_item.c b/fs/xfs/xfs_rmap_item.c
index 49cebd68b672..dc4f0c9f0897 100644
--- a/fs/xfs/xfs_rmap_item.c
+++ b/fs/xfs/xfs_rmap_item.c
@@ -337,8 +337,8 @@ xfs_trans_log_finish_rmap_update(
 static int
 xfs_rmap_update_diff_items(
 	void				*priv,
-	struct list_head		*a,
-	struct list_head		*b)
+	const struct list_head		*a,
+	const struct list_head		*b)
 {
 	struct xfs_mount		*mp = priv;
 	struct xfs_rmap_intent		*ra;