[PATCH 4/8] erofs-utils: lib: fix buffer leaks in error paths

[Yifan Zhao <stopire@gmail.com>]

Fragment data is already written before its buffer is shrunk.
A failed realloc() should leave the original buffer valid, so the
fragment commit can continue without shrinking it.

Also fix an inline data buffer leak when loading compressed metadata
fails during rebuild.

Fixes: 84bae6acdbee ("erofs-utils: lib: keep full data until the fragment is committed")
Fixes: 1c230a485f25 ("erofs-utils: mkfs: support rebuild mode for compressed inodes")
Assisted-by: Codex:gpt-6-astra
Assisted-by: Claude Code:deepseek-v4.1-flash-1017
Signed-off-by: Yifan Zhao <stopire@gmail.com>
---
 lib/compress.c  | 2 ++
 lib/fragments.c | 8 ++------
 2 files changed, 4 insertions(+), 6 deletions(-)

diff --git a/lib/compress.c b/lib/compress.c
index e1cfc05..b5f75ca 100644
--- a/lib/compress.c
+++ b/lib/compress.c
@@ -2607,6 +2607,8 @@ int z_erofs_rebuild_load_metadata(struct erofs_sb_info *dst_sbi,
 err_free_ei:
 	free(ei);
 err_out:
+	free(inode->idata);
+	inode->idata = NULL;
 	list_for_each_entry_safe(ei, n, &extents, list) {
 		list_del(&ei->list);
 		free(ei);
diff --git a/lib/fragments.c b/lib/fragments.c
index d4e79b2..3398888 100644
--- a/lib/fragments.c
+++ b/lib/fragments.c
@@ -366,12 +366,8 @@ int erofs_fragment_commit(struct erofs_inode *inode, u32 tofh)
 		memmove(fi->data, fi->data + fi->length - sz, sz);
 
 		nb = realloc(fi->data, sz);
-		if (!nb) {
-			erofs_up_write(&bk->lock);
-			fi->data = NULL;
-			return -ENOMEM;
-		}
-		fi->data = nb;
+		if (nb)
+			fi->data = nb;
 		fi->pos = (erofs_off_t)offset;
 		erofs_up_write(&bk->lock);
 		inode->fragmentoff = fi->pos - len;
-- 
2.56.0