ext4: Fix optional-arg mount options (15121c18) · Commits · 戴 / test

We have 2 mount options, "barrier" and "auto_da_alloc" which may or may not take a 1/0 argument. This causes the ext4 superblock mount code to subtract uninitialized pointers and pass the result to kmalloc, which results in very noisy failures. Per Ted's suggestion, initialize the args struct so that we know whether match_token() found an argument for the option, and skip match_int() if not. Also, return error (0) from parse_options if we thought we found an argument, but match_int() Fails. Reported-by:

Michael S. Tsirkin <mst@redhat.com> Signed-off-by:

Eric Sandeen <sandeen@redhat.com> Signed-off-by:

"Theodore Ts'o" <tytso@mit.edu>

fs/ext4/super.c

+15 −8

Original line number	Diff line number	Diff line
		@@ -1229,6 +1229,11 @@ static int parse_options(char options, struct super_block sb,
		if (!*p)
		continue;

		/*
		* Initialize args struct so we know whether arg was
		* found; some options take optional arguments.
		*/
		args[0].to = args[0].from = 0;
		token = match_token(p, tokens, args);
		switch (token) {
		case Opt_bsd_df:
		@@ -1518,10 +1523,11 @@ set_qf_format:
		clear_opt(sbi->s_mount_opt, BARRIER);
		break;
		case Opt_barrier:
		if (match_int(&args[0], &option)) {
		set_opt(sbi->s_mount_opt, BARRIER);
		break;
		}
		if (args[0].from) {
		if (match_int(&args[0], &option))
		return 0;
		} else
		option = 1; /* No argument, default to 1 */
		if (option)
		set_opt(sbi->s_mount_opt, BARRIER);
		else
		@@ -1594,10 +1600,11 @@ set_qf_format:
		set_opt(sbi->s_mount_opt,NO_AUTO_DA_ALLOC);
		break;
		case Opt_auto_da_alloc:
		if (match_int(&args[0], &option)) {
		clear_opt(sbi->s_mount_opt, NO_AUTO_DA_ALLOC);
		break;
		}
		if (args[0].from) {
		if (match_int(&args[0], &option))
		return 0;
		} else
		option = 1; /* No argument, default to 1 */
		if (option)
		clear_opt(sbi->s_mount_opt, NO_AUTO_DA_ALLOC);
		else

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