[PATCH] f2fs: validate inline dentry name lengths before conversion

[Samuel Moelius <sam.moelius@trailofbits.com>]

Inline dentry conversion copies names out of the inline dentry area
before checking that each recorded name length fits in the available
filename slots.

A corrupted image can therefore make the conversion path read past
the inline filename storage while building the regular dentry block.

Validate each inline dentry name length against the inline filename
area before copying it.

Assisted-by: Codex:gpt-5.5-cyber-preview
Signed-off-by: Samuel Moelius <sam.moelius@trailofbits.com>
---
 fs/f2fs/inline.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/fs/f2fs/inline.c b/fs/f2fs/inline.c
index 7aabfc9b43cb..4584dfbe3fb8 100644
--- a/fs/f2fs/inline.c
+++ b/fs/f2fs/inline.c
@@ -507,6 +507,10 @@ static int f2fs_add_inline_entries(struct inode *dir, void *inline_dentry)
 			bit_pos++;
 			continue;
 		}
+		if (unlikely(le16_to_cpu(de->name_len) > F2FS_NAME_LEN ||
+			     bit_pos + GET_DENTRY_SLOTS(le16_to_cpu(de->name_len)) >
+			     d.max))
+			return -EFSCORRUPTED;
 
 		/*
 		 * We only need the disk_name and hash to move the dentry.
-- 
2.43.0