commit ba63f23d69a3a10e7e527a02702023da68ef8a6d upstream, backported to fs/ext4/ioctl.c for pre-4.8 kernels. Since setting an encryption policy requires writing metadata to the filesystem, it should be guarded by mnt_want_write/mnt_drop_write. Otherwise, a user could cause a write to a frozen or readonly filesystem. This was handled correctly by f2fs but not by ext4. Signed-off-by: Eric Biggers <ebiggers@xxxxxxxxxx> --- fs/ext4/ioctl.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/fs/ext4/ioctl.c b/fs/ext4/ioctl.c index 28cc412..64eddc5 100644 --- a/fs/ext4/ioctl.c +++ b/fs/ext4/ioctl.c @@ -782,7 +782,13 @@ resizefs_out: goto encryption_policy_out; } + err = mnt_want_write_file(filp); + if (err) + goto encryption_policy_out; + err = ext4_process_policy(&policy, inode); + + mnt_drop_write_file(filp); encryption_policy_out: return err; #else -- 2.8.0.rc3.226.g39d4020 -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html