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Subject[PATCH] drivers/staging/exfat - by default, prohibit mount of fat/vfat
Date
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);
}
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