[PATCH] btrfs: fix oob Read in getname_kernel

Edward Adam Davis
2023-12-19T10:25:21Z

If ioctl does not pass in the correct tgtdev_name string, oob will occur because
"\0" cannot be found.

Reported-and-tested-by: syzbot+33f23b49ac24f986c9e8@syzkaller.appspotmail.com
Signed-off-by: Edward Adam Davis <eadavis@qq.com>
---
fs/btrfs/dev-replace.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/fs/btrfs/dev-replace.c b/fs/btrfs/dev-replace.c
index f9544fda38e9..e7e96e57f682 100644
--- a/fs/btrfs/dev-replace.c
+++ b/fs/btrfs/dev-replace.c
@@ -730,7 +730,7 @@ static int btrfs_dev_replace_start(struct btrfs_fs_info *fs_info,
int btrfs_dev_replace_by_ioctl(struct btrfs_fs_info *fs_info,
struct btrfs_ioctl_dev_replace_args *args)
{
- int ret;
+ int ret, len;

switch (args->start.cont_reading_from_srcdev_mode) {
case BTRFS_IOCTL_DEV_REPLACE_CONT_READING_FROM_SRCDEV_MODE_ALWAYS:
@@ -740,8 +740,10 @@ int btrfs_dev_replace_by_ioctl(struct btrfs_fs_info *fs_info,
return -EINVAL;
}

+ len = strnlen(args->start.tgtdev_name, BTRFS_DEVICE_PATH_NAME_MAX + 1);
if ((args->start.srcdevid == 0 && args->start.srcdev_name[0] == '\0') ||
- args->start.tgtdev_name[0] == '\0')
+ args->start.tgtdev_name[0] == '\0' ||
+ len == BTRFS_DEVICE_PATH_NAME_MAX + 1)
return -EINVAL;

ret = btrfs_dev_replace_start(fs_info, args->start.tgtdev_name,
--
2.43.0