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From: "Valdis Klētnieks" <valdis.kletnieks@vt.edu>
To: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Sasha Levin <alexander.levin@microsoft.com>,
	Christoph Hellwig <hch@infradead.org>
Cc: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: [PATCH] drivers/staging/exfat - by default, prohibit mount of fat/vfat
Date: Fri, 30 Aug 2019 12:42:39 -0400	[thread overview]
Message-ID: <245727.1567183359@turing-police> (raw)

Concerns have been raised about the exfat driver accidentally mounting
fat/vfat file systems.  Add an extra configure option to help prevent that.

Suggested-by: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Valdis Kletnieks <valdis.kletnieks@vt.edu>

diff --git a/drivers/staging/exfat/Kconfig b/drivers/staging/exfat/Kconfig
index 78b32aa2ca19..1df177b1dc72 100644
--- a/drivers/staging/exfat/Kconfig
+++ b/drivers/staging/exfat/Kconfig
@@ -4,6 +4,14 @@ config EXFAT_FS
 	help
 	  This adds support for the exFAT file system.
 
+config EXFAT_DONT_MOUNT_VFAT
+	bool "Prohibit mounting of fat/vfat filesysems by exFAT"
+	default y
+	help
+	  By default, the exFAT driver will only mount exFAT filesystems, and refuse
+	  to mount fat/vfat filesystems.  Set this to 'n' to allow the exFAT driver
+	  to mount these filesystems.
+
 config EXFAT_DISCARD
 	bool "enable discard support"
 	depends on EXFAT_FS
diff --git a/drivers/staging/exfat/exfat_super.c b/drivers/staging/exfat/exfat_super.c
index 5b5c2ca8c9aa..7fdb5b8bc928 100644
--- a/drivers/staging/exfat/exfat_super.c
+++ b/drivers/staging/exfat/exfat_super.c
@@ -486,10 +486,16 @@ static int ffsMountVol(struct super_block *sb)
 			break;
 
 	if (i < 53) {
+#ifdef CONFIG_EXFAT_DONT_MOUNT_VFAT
+		ret = -EINVAL;
+		printk(KERN_INFO "EXFAT: Attempted to mount VFAT filesystem\n");
+		goto out;
+#else
 		if (GET16(p_pbr->bpb + 11)) /* num_fat_sectors */
 			ret = fat16_mount(sb, p_pbr);
 		else
 			ret = fat32_mount(sb, p_pbr);
+#endif
 	} else {
 		ret = exfat_mount(sb, p_pbr);
 	}


             reply	other threads:[~2019-08-30 16:42 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-08-30 16:42 Valdis Klētnieks [this message]
2019-08-30 16:45 ` [PATCH] drivers/staging/exfat - by default, prohibit mount of fat/vfat Christoph Hellwig
2019-08-31  0:48   ` Valdis Klētnieks
2019-08-31  6:46     ` Christoph Hellwig
2019-08-31 10:25       ` Valdis Klētnieks
2019-08-31 14:24         ` Andy Shevchenko
2019-08-31 14:51           ` Valdis Klētnieks
2019-09-01  1:07         ` Dave Chinner
2019-09-01  1:37           ` Gao Xiang
2019-09-01  3:05             ` Al Viro
2019-09-01  3:26               ` Gao Xiang
2019-09-01  3:37           ` Valdis Klētnieks
2019-09-01 22:43             ` Dave Chinner
2019-09-01 23:13               ` Valdis Klētnieks
2019-09-02  7:38                 ` Christoph Hellwig
2019-09-02  7:35         ` Christoph Hellwig
2019-09-02 15:25           ` Greg Kroah-Hartman
2019-09-02 19:00             ` Valdis Klētnieks
2019-09-02 19:06               ` Greg Kroah-Hartman
2019-09-08 10:50                 ` OGAWA Hirofumi

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