From: Darrick J. Wong <djwong@kernel.org>
Date: Thu, 7 Aug 2025 17:30:34 +0000 (-0700)
Subject: fuse2fs: fix readlink failure
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=bc1279f60fde251991030d3aaec7711d2c6eb4b0;p=thirdparty%2Fe2fsprogs.git

fuse2fs: fix readlink failure

For readlink of slow symlinks, an IO error when reading the link target
cause memory corruption.  This happens because the error case for
ext2fs_file_read closes the file, translates the error, but then jumps
down to the regular termination code, which re-closes the file and is
hence a UAF.  Straighten out the error paths to eliminate the UAF.
Also fix the bug that short target reads aren't flagged as corruption
as is done in the kernel.

Cc: <linux-ext4@vger.kernel.org> # v1.43
Fixes: 81cbf1ef4f5dab ("misc: add fuse2fs, a FUSE server for e2fsprogs")
Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---

diff --git a/misc/fuse2fs.c b/misc/fuse2fs.c
index 4d42a634..f9da9c1a 100644
--- a/misc/fuse2fs.c
+++ b/misc/fuse2fs.c
@@ -1086,13 +1086,11 @@ static int op_readlink(const char *path, char *buf, size_t len)
 		}
 
 		err = ext2fs_file_read(file, buf, len, &got);
-		if (err || got != len) {
-			ext2fs_file_close(file);
+		if (err)
 			ret = translate_error(fs, ino, err);
-			goto out2;
-		}
+		else if (got != len)
+			ret = translate_error(fs, ino, EXT2_ET_INODE_CORRUPTED);
 
-out2:
 		err = ext2fs_file_close(file);
 		if (ret)
 			goto out;