[PATCH] staging: erofs: refuse to mount images with malformed volume name

From: Gao Xiang
Date: Sun Aug 18 2019 - 06:29:14 EST


From: Gao Xiang <gaoxiang25@xxxxxxxxxx>

As Richard reminder [1], A valid volume name should be
ended in NIL terminator within the length of volume_name.

Since this field currently isn't really used, let's fix
it to avoid potential bugs in the future.

[1] https://lore.kernel.org/r/1133002215.69049.1566119033047.JavaMail.zimbra@xxxxxx/

Reported-by: Richard Weinberger <richard@xxxxxx>
Signed-off-by: Gao Xiang <gaoxiang25@xxxxxxxxxx>
---
drivers/staging/erofs/super.c | 9 +++++++--
1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/drivers/staging/erofs/super.c b/drivers/staging/erofs/super.c
index f65a1ff9f42f..2da471010a86 100644
--- a/drivers/staging/erofs/super.c
+++ b/drivers/staging/erofs/super.c
@@ -131,9 +131,14 @@ static int superblock_read(struct super_block *sb)
sbi->build_time_nsec = le32_to_cpu(layout->build_time_nsec);

memcpy(&sb->s_uuid, layout->uuid, sizeof(layout->uuid));
- memcpy(sbi->volume_name, layout->volume_name,
- sizeof(layout->volume_name));

+ ret = strscpy(sbi->volume_name, layout->volume_name,
+ sizeof(layout->volume_name));
+ if (ret < 0) { /* -E2BIG */
+ errln("bad volume name without NIL terminator");
+ ret = -EFSCORRUPTED;
+ goto out;
+ }
ret = 0;
out:
brelse(bh);
--
2.17.1