Add extra checks for bad symlinks, including zero length symlinks,

too long i_size for slow and fast symlinks, i_size_high set, multiple
blocks for slow symlinks.

e2fsck/e2fsck.h

@@ -316,6 +316,7 @@ extern int e2fsck_run_ext3_journal(e2fsck_t ctx);
 /* pass1.c */
 extern void e2fsck_use_inode_shortcuts(e2fsck_t ctx, int bool);
 extern int e2fsck_pass1_check_device_inode(struct ext2_inode *inode);
+extern int e2fsck_pass1_check_symlink(ext2_filsys fs, struct ext2_inode *inode);
 
 /* pass2.c */
 extern int e2fsck_process_bad_inode(e2fsck_t ctx, ext2_ino_t dir, ext2_ino_t ino);

e2fsck/pass1.c

@@ -146,6 +146,44 @@ int e2fsck_pass1_check_device_inode(struct ext2_inode *inode)
 	return 1;
 }
 
+/*
+ * Check to make sure a symlink inode is real.  Returns 1 if the symlink
+ * checks out, 0 if not.
+ */
+int e2fsck_pass1_check_symlink(ext2_filsys fs, struct ext2_inode *inode)
+{
+	if (inode->i_size_high || inode->i_size == 0)
+		return 0;
+
+	if (inode->i_flags & (EXT2_IMMUTABLE_FL |EXT2_APPEND_FL |EXT2_INDEX_FL))
+		return 0;
+
+	if (inode->i_blocks) {
+		int i;
+
+		if (inode->i_blocks > fs->blocksize >> 9)
+			return 0;
+
+		for (i = 1; i < EXT2_N_BLOCKS; i++)
+			if (inode->i_block[i])
+				return 0;
+
+		if (inode->i_size > fs->blocksize)
+			return 0;
+
+		/* Defer check of i_size until block number validated  */
+	} else {
+		if (inode->i_size > EXT2_LINK_DIR - 1)
+			return 0;
+
+		if (inode->i_size !=
+		    strnlen((char *)inode->i_block, EXT2_LINK_DIR))
+			return 0;
+	}
+
+	return 1;
+}
+
 /*
  * If the immutable (or append-only) flag is set on the inode, offer
  * to clear it.
@@ -561,10 +599,9 @@ void e2fsck_pass1(e2fsck_t ctx)
 		} else if (LINUX_S_ISLNK (inode.i_mode)) {
 			check_immutable(ctx, &pctx);
 			ctx->fs_symlinks_count++;
+			if (!e2fsck_pass1_check_symlink(fs, &inode))
+				mark_inode_bad(ctx, ino);
 			if (!inode.i_blocks) {
-				if (inode.i_size_high ||
-				    (inode.i_size > EXT2_N_BLOCKS*4))
-					mark_inode_bad(ctx, ino);
 				ctx->fs_fast_symlinks_count++;
 				goto next;
 			}
@@ -1216,12 +1253,16 @@ static void check_blocks(e2fsck_t ctx, struct problem_context *pctx,
 		}
 		pctx->num = 0;
 	}
-	if (!pb.is_dir && (inode->i_size_high || inode->i_size & 0x80000000UL))
+	if (!pb.is_dir &&
+	    (inode->i_size_high || inode->i_size & 0x80000000UL) &&
+	    !ext2fs_test_inode_bitmap(ctx->inode_bad_map, ino))
 		ctx->large_files++;
 	if (pb.num_blocks != inode->i_blocks) {
 		pctx->num = pb.num_blocks;
 		if (fix_problem(ctx, PR_1_BAD_I_BLOCKS, pctx)) {
 			inode->i_blocks = pb.num_blocks;
+			if (LINUX_S_ISLNK(inode->i_mode))
+				mark_inode_bad(ctx, ino);
 			e2fsck_write_inode(ctx, ino, inode, "check_blocks");
 		}
 		pctx->num = 0;

e2fsck/pass2.c

@@ -699,9 +699,10 @@ extern int e2fsck_process_bad_inode(e2fsck_t ctx, ext2_ino_t dir,
 		 && !e2fsck_pass1_check_device_inode(&inode))
 		problem = PR_2_BAD_SOCKET;
 	else if (LINUX_S_ISLNK(inode.i_mode)
-		 && (inode.i_size_high ||
-		     (inode.i_size > EXT2_N_BLOCKS*4)))
+		 && !e2fsck_pass1_check_symlink(fs, &inode)) {
+		pctx.str = inode.i_blocks ? "" : "fast ";
 		problem = PR_2_SYMLINK_SIZE;
+	}
 
 	if (problem) {
 		if (fix_problem(ctx, problem, &pctx)) {

e2fsck/problem.c

@@ -928,7 +928,7 @@ static const struct e2fsck_problem problem_table[] = {
 
 	/* Invalid fast symlink size */
 	{ PR_2_SYMLINK_SIZE,
-	  N_("@i %i (%Q) is a fast symlink with a bad size (%Is)\n"),
+	  N_("@i %i (%Q) is a %ssymlink with a bad size (%Is)\n"),
 	  PROMPT_CLEAR, 0 },
 
   	/* i_file_acl (extended attribute block) is bad */

lib/ext2fs/ext2_fs.h

@@ -169,6 +169,8 @@ struct ext2_group_desc
 #define	EXT2_TIND_BLOCK			(EXT2_DIND_BLOCK + 1)
 #define	EXT2_N_BLOCKS			(EXT2_TIND_BLOCK + 1)
 
+#define EXT2_LINK_DIR			(EXT2_N_BLOCKS * 4)
+
 /*
  * Inode flags
  */

tests/ChangeLog

@@ -1,3 +1,7 @@
+2001-07-26  Andreas Dilger  <adilger@turbolinux.com>
+
+	* f_symlinks: Add several fast symlink error cases to test.
+
 2001-07-27  Theodore Tso  <tytso@valinux.com>
 
 	* f_filetype: Update expect.1 to match changed problem message

tests/README

@@ -63,5 +63,6 @@ noroot.img		Filesystem with a deleted root directory
 okgroup.img		Filesystem that's exactly 8193 blocks long 
 				(otherwise OK)
 overfsblks.img		Filesystem with overlapping inode and block bitmaps
+symlinks.img		Filesystem with bad symlink sizes